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-rw-r--r--vendor/github.com/klauspost/compress/LICENSE27
-rw-r--r--vendor/github.com/klauspost/compress/README.md160
-rw-r--r--vendor/github.com/klauspost/compress/flate/copy.go32
-rw-r--r--vendor/github.com/klauspost/compress/flate/crc32_amd64.go42
-rw-r--r--vendor/github.com/klauspost/compress/flate/crc32_amd64.s214
-rw-r--r--vendor/github.com/klauspost/compress/flate/crc32_noasm.go35
-rw-r--r--vendor/github.com/klauspost/compress/flate/deflate.go1353
-rw-r--r--vendor/github.com/klauspost/compress/flate/dict_decoder.go184
-rw-r--r--vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go701
-rw-r--r--vendor/github.com/klauspost/compress/flate/huffman_code.go344
-rw-r--r--vendor/github.com/klauspost/compress/flate/inflate.go880
-rw-r--r--vendor/github.com/klauspost/compress/flate/reverse_bits.go48
-rw-r--r--vendor/github.com/klauspost/compress/flate/snappy.go900
-rw-r--r--vendor/github.com/klauspost/compress/flate/token.go115
14 files changed, 5035 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/LICENSE b/vendor/github.com/klauspost/compress/LICENSE
new file mode 100644
index 000000000..744875676
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+ * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+ * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/klauspost/compress/README.md b/vendor/github.com/klauspost/compress/README.md
new file mode 100644
index 000000000..280d54890
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/README.md
@@ -0,0 +1,160 @@
+# compress
+
+This package is based on an optimized Deflate function, which is used by gzip/zip/zlib packages.
+
+It offers slightly better compression at lower compression settings, and up to 3x faster encoding at highest compression level.
+
+* [High Throughput Benchmark](http://blog.klauspost.com/go-gzipdeflate-benchmarks/).
+* [Small Payload/Webserver Benchmarks](http://blog.klauspost.com/gzip-performance-for-go-webservers/).
+* [Linear Time Compression](http://blog.klauspost.com/constant-time-gzipzip-compression/).
+* [Re-balancing Deflate Compression Levels](https://blog.klauspost.com/rebalancing-deflate-compression-levels/)
+
+[![Build Status](https://travis-ci.org/klauspost/compress.svg?branch=master)](https://travis-ci.org/klauspost/compress)
+[![Sourcegraph Badge](https://sourcegraph.com/github.com/klauspost/compress/-/badge.svg)](https://sourcegraph.com/github.com/klauspost/compress?badge)
+
+# changelog
+
+* Aug 1, 2018: Added [huff0 README](https://github.com/klauspost/compress/tree/master/huff0#huff0-entropy-compression).
+* Jul 8, 2018: Added [Performance Update 2018](#performance-update-2018) below.
+* Jun 23, 2018: Merged [Go 1.11 inflate optimizations](https://go-review.googlesource.com/c/go/+/102235). Go 1.9 is now required. Backwards compatible version tagged with [v1.3.0](https://github.com/klauspost/compress/releases/tag/v1.3.0).
+* Apr 2, 2018: Added [huff0](https://godoc.org/github.com/klauspost/compress/huff0) en/decoder. Experimental for now, API may change.
+* Mar 4, 2018: Added [FSE Entropy](https://godoc.org/github.com/klauspost/compress/fse) en/decoder. Experimental for now, API may change.
+* Nov 3, 2017: Add compression [Estimate](https://godoc.org/github.com/klauspost/compress#Estimate) function.
+* May 28, 2017: Reduce allocations when resetting decoder.
+* Apr 02, 2017: Change back to official crc32, since changes were merged in Go 1.7.
+* Jan 14, 2017: Reduce stack pressure due to array copies. See [Issue #18625](https://github.com/golang/go/issues/18625).
+* Oct 25, 2016: Level 2-4 have been rewritten and now offers significantly better performance than before.
+* Oct 20, 2016: Port zlib changes from Go 1.7 to fix zlib writer issue. Please update.
+* Oct 16, 2016: Go 1.7 changes merged. Apples to apples this package is a few percent faster, but has a significantly better balance between speed and compression per level.
+* Mar 24, 2016: Always attempt Huffman encoding on level 4-7. This improves base 64 encoded data compression.
+* Mar 24, 2016: Small speedup for level 1-3.
+* Feb 19, 2016: Faster bit writer, level -2 is 15% faster, level 1 is 4% faster.
+* Feb 19, 2016: Handle small payloads faster in level 1-3.
+* Feb 19, 2016: Added faster level 2 + 3 compression modes.
+* Feb 19, 2016: [Rebalanced compression levels](https://blog.klauspost.com/rebalancing-deflate-compression-levels/), so there is a more even progresssion in terms of compression. New default level is 5.
+* Feb 14, 2016: Snappy: Merge upstream changes.
+* Feb 14, 2016: Snappy: Fix aggressive skipping.
+* Feb 14, 2016: Snappy: Update benchmark.
+* Feb 13, 2016: Deflate: Fixed assembler problem that could lead to sub-optimal compression.
+* Feb 12, 2016: Snappy: Added AMD64 SSE 4.2 optimizations to matching, which makes easy to compress material run faster. Typical speedup is around 25%.
+* Feb 9, 2016: Added Snappy package fork. This version is 5-7% faster, much more on hard to compress content.
+* Jan 30, 2016: Optimize level 1 to 3 by not considering static dictionary or storing uncompressed. ~4-5% speedup.
+* Jan 16, 2016: Optimization on deflate level 1,2,3 compression.
+* Jan 8 2016: Merge [CL 18317](https://go-review.googlesource.com/#/c/18317): fix reading, writing of zip64 archives.
+* Dec 8 2015: Make level 1 and -2 deterministic even if write size differs.
+* Dec 8 2015: Split encoding functions, so hashing and matching can potentially be inlined. 1-3% faster on AMD64. 5% faster on other platforms.
+* Dec 8 2015: Fixed rare [one byte out-of bounds read](https://github.com/klauspost/compress/issues/20). Please update!
+* Nov 23 2015: Optimization on token writer. ~2-4% faster. Contributed by [@dsnet](https://github.com/dsnet).
+* Nov 20 2015: Small optimization to bit writer on 64 bit systems.
+* Nov 17 2015: Fixed out-of-bound errors if the underlying Writer returned an error. See [#15](https://github.com/klauspost/compress/issues/15).
+* Nov 12 2015: Added [io.WriterTo](https://golang.org/pkg/io/#WriterTo) support to gzip/inflate.
+* Nov 11 2015: Merged [CL 16669](https://go-review.googlesource.com/#/c/16669/4): archive/zip: enable overriding (de)compressors per file
+* Oct 15 2015: Added skipping on uncompressible data. Random data speed up >5x.
+
+# usage
+
+The packages are drop-in replacements for standard libraries. Simply replace the import path to use them:
+
+| old import | new import |
+|--------------------|-----------------------------------------|
+| `compress/gzip` | `github.com/klauspost/compress/gzip` |
+| `compress/zlib` | `github.com/klauspost/compress/zlib` |
+| `archive/zip` | `github.com/klauspost/compress/zip` |
+| `compress/flate` | `github.com/klauspost/compress/flate` |
+
+You may also be interested in [pgzip](https://github.com/klauspost/pgzip), which is a drop in replacement for gzip, which support multithreaded compression on big files and the optimized [crc32](https://github.com/klauspost/crc32) package used by these packages.
+
+The packages contains the same as the standard library, so you can use the godoc for that: [gzip](http://golang.org/pkg/compress/gzip/), [zip](http://golang.org/pkg/archive/zip/), [zlib](http://golang.org/pkg/compress/zlib/), [flate](http://golang.org/pkg/compress/flate/).
+
+Currently there is only minor speedup on decompression (mostly CRC32 calculation).
+
+# Performance Update 2018
+
+It has been a while since we have been looking at the speed of this package compared to the standard library, so I thought I would re-do my tests and give some overall recommendations based on the current state. All benchmarks have been performed with Go 1.10 on my Desktop Intel(R) Core(TM) i7-2600 CPU @3.40GHz. Since I last ran the tests, I have gotten more RAM, which means tests with big files are no longer limited by my SSD.
+
+The raw results are in my [updated spreadsheet](https://docs.google.com/spreadsheets/d/1nuNE2nPfuINCZJRMt6wFWhKpToF95I47XjSsc-1rbPQ/edit?usp=sharing). Due to cgo changes and upstream updates i could not get the cgo version of gzip to compile. Instead I included the [zstd](https://github.com/datadog/zstd) cgo implementation. If I get cgo gzip to work again, I might replace the results in the sheet.
+
+The columns to take note of are: *MB/s* - the throughput. *Reduction* - the data size reduction in percent of the original. *Rel Speed* relative speed compared to the standard libary at the same level. *Smaller* - how many percent smaller is the compressed output compared to stdlib. Negative means the output was bigger. *Loss* means the loss (or gain) in compression as a percentage difference of the input.
+
+The `gzstd` (standard library gzip) and `gzkp` (this package gzip) only uses one CPU core. [`pgzip`](https://github.com/klauspost/pgzip), [`bgzf`](https://github.com/biogo/hts/bgzf) uses all 4 cores. [`zstd`](https://github.com/DataDog/zstd) uses one core, and is a beast (but not Go, yet).
+
+
+## Overall differences.
+
+There appears to be a roughly 5-10% speed advantage over the standard library when comparing at similar compression levels.
+
+The biggest difference you will see is the result of [re-balancing](https://blog.klauspost.com/rebalancing-deflate-compression-levels/) the compression levels. I wanted by library to give a smoother transition between the compression levels than the standard library.
+
+This package attempts to provide a more smooth transition, where "1" is taking a lot of shortcuts, "5" is the reasonable trade-off and "9" is the "give me the best compression", and the values in between gives something reasonable in between. The standard library has big differences in levels 1-4, but levels 5-9 having no significant gains - often spending a lot more time than can be justified by the achieved compression.
+
+There are links to all the test data in the [spreadsheet](https://docs.google.com/spreadsheets/d/1nuNE2nPfuINCZJRMt6wFWhKpToF95I47XjSsc-1rbPQ/edit?usp=sharing) in the top left field on each tab.
+
+## Web Content
+
+This test set aims to emulate typical use in a web server. The test-set is 4GB data in 53k files, and is a mixture of (mostly) HTML, JS, CSS.
+
+Since level 1 and 9 are close to being the same code, they are quite close. But looking at the levels in-between the differences are quite big.
+
+Looking at level 6, this package is 88% faster, but will output about 6% more data. For a web server, this means you can serve 88% more data, but have to pay for 6% more bandwidth. You can draw your own conclusions on what would be the most expensive for your case.
+
+## Object files
+
+This test is for typical data files stored on a server. In this case it is a collection of Go precompiled objects. They are very compressible.
+
+The picture is similar to the web content, but with small differences since this is very compressible. Levels 2-3 offer good speed, but is sacrificing quite a bit of compression.
+
+The standard library seems suboptimal on level 3 and 4 - offering both worse compression and speed than level 6 & 7 of this package respectively.
+
+## Highly Compressible File
+
+This is a JSON file with very high redundancy. The reduction starts at 95% on level 1, so in real life terms we are dealing with something like a highly redundant stream of data, etc.
+
+It is definitely visible that we are dealing with specialized content here, so the results are very scattered. This package does not do very well at levels 1-4, but picks up significantly at level 5 and levels 7 and 8 offering great speed for the achieved compression.
+
+So if you know you content is extremely compressible you might want to go slightly higher than the defaults. The standard library has a huge gap between levels 3 and 4 in terms of speed (2.75x slowdown), so it offers little "middle ground".
+
+## Medium-High Compressible
+
+This is a pretty common test corpus: [enwik9](http://mattmahoney.net/dc/textdata.html). It contains the first 10^9 bytes of the English Wikipedia dump on Mar. 3, 2006. This is a very good test of typical text based compression and more data heavy streams.
+
+We see a similar picture here as in "Web Content". On equal levels some compression is sacrificed for more speed. Level 5 seems to be the best trade-off between speed and size, beating stdlib level 3 in both.
+
+## Medium Compressible
+
+I will combine two test sets, one [10GB file set](http://mattmahoney.net/dc/10gb.html) and a VM disk image (~8GB). Both contain different data types and represent a typical backup scenario.
+
+The most notable thing is how quickly the standard libary drops to very low compression speeds around level 5-6 without any big gains in compression. Since this type of data is fairly common, this does not seem like good behavior.
+
+
+## Un-compressible Content
+
+This is mainly a test of how good the algorithms are at detecting un-compressible input. The standard library only offers this feature with very conservative settings at level 1. Obviously there is no reason for the algorithms to try to compress input that cannot be compressed. The only downside is that it might skip some compressible data on false detections.
+
+
+# linear time compression (huffman only)
+
+This compression library adds a special compression level, named `HuffmanOnly`, which allows near linear time compression. This is done by completely disabling matching of previous data, and only reduce the number of bits to represent each character.
+
+This means that often used characters, like 'e' and ' ' (space) in text use the fewest bits to represent, and rare characters like '¤' takes more bits to represent. For more information see [wikipedia](https://en.wikipedia.org/wiki/Huffman_coding) or this nice [video](https://youtu.be/ZdooBTdW5bM).
+
+Since this type of compression has much less variance, the compression speed is mostly unaffected by the input data, and is usually more than *180MB/s* for a single core.
+
+The downside is that the compression ratio is usually considerably worse than even the fastest conventional compression. The compression raio can never be better than 8:1 (12.5%).
+
+The linear time compression can be used as a "better than nothing" mode, where you cannot risk the encoder to slow down on some content. For comparison, the size of the "Twain" text is *233460 bytes* (+29% vs. level 1) and encode speed is 144MB/s (4.5x level 1). So in this case you trade a 30% size increase for a 4 times speedup.
+
+For more information see my blog post on [Fast Linear Time Compression](http://blog.klauspost.com/constant-time-gzipzip-compression/).
+
+This is implemented on Go 1.7 as "Huffman Only" mode, though not exposed for gzip.
+
+
+# snappy package
+
+The standard snappy package has now been improved. This repo contains a copy of the snappy repo.
+
+I would advise to use the standard package: https://github.com/golang/snappy
+
+
+# license
+
+This code is licensed under the same conditions as the original Go code. See LICENSE file.
diff --git a/vendor/github.com/klauspost/compress/flate/copy.go b/vendor/github.com/klauspost/compress/flate/copy.go
new file mode 100644
index 000000000..a3200a8f4
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/copy.go
@@ -0,0 +1,32 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// forwardCopy is like the built-in copy function except that it always goes
+// forward from the start, even if the dst and src overlap.
+// It is equivalent to:
+// for i := 0; i < n; i++ {
+// mem[dst+i] = mem[src+i]
+// }
+func forwardCopy(mem []byte, dst, src, n int) {
+ if dst <= src {
+ copy(mem[dst:dst+n], mem[src:src+n])
+ return
+ }
+ for {
+ if dst >= src+n {
+ copy(mem[dst:dst+n], mem[src:src+n])
+ return
+ }
+ // There is some forward overlap. The destination
+ // will be filled with a repeated pattern of mem[src:src+k].
+ // We copy one instance of the pattern here, then repeat.
+ // Each time around this loop k will double.
+ k := dst - src
+ copy(mem[dst:dst+k], mem[src:src+k])
+ n -= k
+ dst += k
+ }
+}
diff --git a/vendor/github.com/klauspost/compress/flate/crc32_amd64.go b/vendor/github.com/klauspost/compress/flate/crc32_amd64.go
new file mode 100644
index 000000000..8298d309a
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/crc32_amd64.go
@@ -0,0 +1,42 @@
+//+build !noasm
+//+build !appengine
+//+build !gccgo
+
+// Copyright 2015, Klaus Post, see LICENSE for details.
+
+package flate
+
+import (
+ "github.com/klauspost/cpuid"
+)
+
+// crc32sse returns a hash for the first 4 bytes of the slice
+// len(a) must be >= 4.
+//go:noescape
+func crc32sse(a []byte) uint32
+
+// crc32sseAll calculates hashes for each 4-byte set in a.
+// dst must be east len(a) - 4 in size.
+// The size is not checked by the assembly.
+//go:noescape
+func crc32sseAll(a []byte, dst []uint32)
+
+// matchLenSSE4 returns the number of matching bytes in a and b
+// up to length 'max'. Both slices must be at least 'max'
+// bytes in size.
+//
+// TODO: drop the "SSE4" name, since it doesn't use any SSE instructions.
+//
+//go:noescape
+func matchLenSSE4(a, b []byte, max int) int
+
+// histogram accumulates a histogram of b in h.
+// h must be at least 256 entries in length,
+// and must be cleared before calling this function.
+//go:noescape
+func histogram(b []byte, h []int32)
+
+// Detect SSE 4.2 feature.
+func init() {
+ useSSE42 = cpuid.CPU.SSE42()
+}
diff --git a/vendor/github.com/klauspost/compress/flate/crc32_amd64.s b/vendor/github.com/klauspost/compress/flate/crc32_amd64.s
new file mode 100644
index 000000000..a79943727
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/crc32_amd64.s
@@ -0,0 +1,214 @@
+//+build !noasm
+//+build !appengine
+//+build !gccgo
+
+// Copyright 2015, Klaus Post, see LICENSE for details.
+
+// func crc32sse(a []byte) uint32
+TEXT ·crc32sse(SB), 4, $0
+ MOVQ a+0(FP), R10
+ XORQ BX, BX
+
+ // CRC32 dword (R10), EBX
+ BYTE $0xF2; BYTE $0x41; BYTE $0x0f
+ BYTE $0x38; BYTE $0xf1; BYTE $0x1a
+
+ MOVL BX, ret+24(FP)
+ RET
+
+// func crc32sseAll(a []byte, dst []uint32)
+TEXT ·crc32sseAll(SB), 4, $0
+ MOVQ a+0(FP), R8 // R8: src
+ MOVQ a_len+8(FP), R10 // input length
+ MOVQ dst+24(FP), R9 // R9: dst
+ SUBQ $4, R10
+ JS end
+ JZ one_crc
+ MOVQ R10, R13
+ SHRQ $2, R10 // len/4
+ ANDQ $3, R13 // len&3
+ XORQ BX, BX
+ ADDQ $1, R13
+ TESTQ R10, R10
+ JZ rem_loop
+
+crc_loop:
+ MOVQ (R8), R11
+ XORQ BX, BX
+ XORQ DX, DX
+ XORQ DI, DI
+ MOVQ R11, R12
+ SHRQ $8, R11
+ MOVQ R12, AX
+ MOVQ R11, CX
+ SHRQ $16, R12
+ SHRQ $16, R11
+ MOVQ R12, SI
+
+ // CRC32 EAX, EBX
+ BYTE $0xF2; BYTE $0x0f
+ BYTE $0x38; BYTE $0xf1; BYTE $0xd8
+
+ // CRC32 ECX, EDX
+ BYTE $0xF2; BYTE $0x0f
+ BYTE $0x38; BYTE $0xf1; BYTE $0xd1
+
+ // CRC32 ESI, EDI
+ BYTE $0xF2; BYTE $0x0f
+ BYTE $0x38; BYTE $0xf1; BYTE $0xfe
+ MOVL BX, (R9)
+ MOVL DX, 4(R9)
+ MOVL DI, 8(R9)
+
+ XORQ BX, BX
+ MOVL R11, AX
+
+ // CRC32 EAX, EBX
+ BYTE $0xF2; BYTE $0x0f
+ BYTE $0x38; BYTE $0xf1; BYTE $0xd8
+ MOVL BX, 12(R9)
+
+ ADDQ $16, R9
+ ADDQ $4, R8
+ XORQ BX, BX
+ SUBQ $1, R10
+ JNZ crc_loop
+
+rem_loop:
+ MOVL (R8), AX
+
+ // CRC32 EAX, EBX
+ BYTE $0xF2; BYTE $0x0f
+ BYTE $0x38; BYTE $0xf1; BYTE $0xd8
+
+ MOVL BX, (R9)
+ ADDQ $4, R9
+ ADDQ $1, R8
+ XORQ BX, BX
+ SUBQ $1, R13
+ JNZ rem_loop
+
+end:
+ RET
+
+one_crc:
+ MOVQ $1, R13
+ XORQ BX, BX
+ JMP rem_loop
+
+// func matchLenSSE4(a, b []byte, max int) int
+TEXT ·matchLenSSE4(SB), 4, $0
+ MOVQ a_base+0(FP), SI
+ MOVQ b_base+24(FP), DI
+ MOVQ DI, DX
+ MOVQ max+48(FP), CX
+
+cmp8:
+ // As long as we are 8 or more bytes before the end of max, we can load and
+ // compare 8 bytes at a time. If those 8 bytes are equal, repeat.
+ CMPQ CX, $8
+ JLT cmp1
+ MOVQ (SI), AX
+ MOVQ (DI), BX
+ CMPQ AX, BX
+ JNE bsf
+ ADDQ $8, SI
+ ADDQ $8, DI
+ SUBQ $8, CX
+ JMP cmp8
+
+bsf:
+ // If those 8 bytes were not equal, XOR the two 8 byte values, and return
+ // the index of the first byte that differs. The BSF instruction finds the
+ // least significant 1 bit, the amd64 architecture is little-endian, and
+ // the shift by 3 converts a bit index to a byte index.
+ XORQ AX, BX
+ BSFQ BX, BX
+ SHRQ $3, BX
+ ADDQ BX, DI
+
+ // Subtract off &b[0] to convert from &b[ret] to ret, and return.
+ SUBQ DX, DI
+ MOVQ DI, ret+56(FP)
+ RET
+
+cmp1:
+ // In the slices' tail, compare 1 byte at a time.
+ CMPQ CX, $0
+ JEQ matchLenEnd
+ MOVB (SI), AX
+ MOVB (DI), BX
+ CMPB AX, BX
+ JNE matchLenEnd
+ ADDQ $1, SI
+ ADDQ $1, DI
+ SUBQ $1, CX
+ JMP cmp1
+
+matchLenEnd:
+ // Subtract off &b[0] to convert from &b[ret] to ret, and return.
+ SUBQ DX, DI
+ MOVQ DI, ret+56(FP)
+ RET
+
+// func histogram(b []byte, h []int32)
+TEXT ·histogram(SB), 4, $0
+ MOVQ b+0(FP), SI // SI: &b
+ MOVQ b_len+8(FP), R9 // R9: len(b)
+ MOVQ h+24(FP), DI // DI: Histogram
+ MOVQ R9, R8
+ SHRQ $3, R8
+ JZ hist1
+ XORQ R11, R11
+
+loop_hist8:
+ MOVQ (SI), R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ MOVB R10, R11
+ INCL (DI)(R11*4)
+ SHRQ $8, R10
+
+ INCL (DI)(R10*4)
+
+ ADDQ $8, SI
+ DECQ R8
+ JNZ loop_hist8
+
+hist1:
+ ANDQ $7, R9
+ JZ end_hist
+ XORQ R10, R10
+
+loop_hist1:
+ MOVB (SI), R10
+ INCL (DI)(R10*4)
+ INCQ SI
+ DECQ R9
+ JNZ loop_hist1
+
+end_hist:
+ RET
diff --git a/vendor/github.com/klauspost/compress/flate/crc32_noasm.go b/vendor/github.com/klauspost/compress/flate/crc32_noasm.go
new file mode 100644
index 000000000..dcf43bd50
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/crc32_noasm.go
@@ -0,0 +1,35 @@
+//+build !amd64 noasm appengine gccgo
+
+// Copyright 2015, Klaus Post, see LICENSE for details.
+
+package flate
+
+func init() {
+ useSSE42 = false
+}
+
+// crc32sse should never be called.
+func crc32sse(a []byte) uint32 {
+ panic("no assembler")
+}
+
+// crc32sseAll should never be called.
+func crc32sseAll(a []byte, dst []uint32) {
+ panic("no assembler")
+}
+
+// matchLenSSE4 should never be called.
+func matchLenSSE4(a, b []byte, max int) int {
+ panic("no assembler")
+ return 0
+}
+
+// histogram accumulates a histogram of b in h.
+//
+// len(h) must be >= 256, and h's elements must be all zeroes.
+func histogram(b []byte, h []int32) {
+ h = h[:256]
+ for _, t := range b {
+ h[t]++
+ }
+}
diff --git a/vendor/github.com/klauspost/compress/flate/deflate.go b/vendor/github.com/klauspost/compress/flate/deflate.go
new file mode 100644
index 000000000..9e6e7ff0c
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/deflate.go
@@ -0,0 +1,1353 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Copyright (c) 2015 Klaus Post
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+ "fmt"
+ "io"
+ "math"
+)
+
+const (
+ NoCompression = 0
+ BestSpeed = 1
+ BestCompression = 9
+ DefaultCompression = -1
+
+ // HuffmanOnly disables Lempel-Ziv match searching and only performs Huffman
+ // entropy encoding. This mode is useful in compressing data that has
+ // already been compressed with an LZ style algorithm (e.g. Snappy or LZ4)
+ // that lacks an entropy encoder. Compression gains are achieved when
+ // certain bytes in the input stream occur more frequently than others.
+ //
+ // Note that HuffmanOnly produces a compressed output that is
+ // RFC 1951 compliant. That is, any valid DEFLATE decompressor will
+ // continue to be able to decompress this output.
+ HuffmanOnly = -2
+ ConstantCompression = HuffmanOnly // compatibility alias.
+
+ logWindowSize = 15
+ windowSize = 1 << logWindowSize
+ windowMask = windowSize - 1
+ logMaxOffsetSize = 15 // Standard DEFLATE
+ minMatchLength = 4 // The smallest match that the compressor looks for
+ maxMatchLength = 258 // The longest match for the compressor
+ minOffsetSize = 1 // The shortest offset that makes any sense
+
+ // The maximum number of tokens we put into a single flat block, just too
+ // stop things from getting too large.
+ maxFlateBlockTokens = 1 << 14
+ maxStoreBlockSize = 65535
+ hashBits = 17 // After 17 performance degrades
+ hashSize = 1 << hashBits
+ hashMask = (1 << hashBits) - 1
+ hashShift = (hashBits + minMatchLength - 1) / minMatchLength
+ maxHashOffset = 1 << 24
+
+ skipNever = math.MaxInt32
+)
+
+var useSSE42 bool
+
+type compressionLevel struct {
+ good, lazy, nice, chain, fastSkipHashing, level int
+}
+
+// Compression levels have been rebalanced from zlib deflate defaults
+// to give a bigger spread in speed and compression.
+// See https://blog.klauspost.com/rebalancing-deflate-compression-levels/
+var levels = []compressionLevel{
+ {}, // 0
+ // Level 1-4 uses specialized algorithm - values not used
+ {0, 0, 0, 0, 0, 1},
+ {0, 0, 0, 0, 0, 2},
+ {0, 0, 0, 0, 0, 3},
+ {0, 0, 0, 0, 0, 4},
+ // For levels 5-6 we don't bother trying with lazy matches.
+ // Lazy matching is at least 30% slower, with 1.5% increase.
+ {6, 0, 12, 8, 12, 5},
+ {8, 0, 24, 16, 16, 6},
+ // Levels 7-9 use increasingly more lazy matching
+ // and increasingly stringent conditions for "good enough".
+ {8, 8, 24, 16, skipNever, 7},
+ {10, 16, 24, 64, skipNever, 8},
+ {32, 258, 258, 4096, skipNever, 9},
+}
+
+type compressor struct {
+ compressionLevel
+
+ w *huffmanBitWriter
+ bulkHasher func([]byte, []uint32)
+
+ // compression algorithm
+ fill func(*compressor, []byte) int // copy data to window
+ step func(*compressor) // process window
+ sync bool // requesting flush
+
+ // Input hash chains
+ // hashHead[hashValue] contains the largest inputIndex with the specified hash value
+ // If hashHead[hashValue] is within the current window, then
+ // hashPrev[hashHead[hashValue] & windowMask] contains the previous index
+ // with the same hash value.
+ chainHead int
+ hashHead [hashSize]uint32
+ hashPrev [windowSize]uint32
+ hashOffset int
+
+ // input window: unprocessed data is window[index:windowEnd]
+ index int
+ window []byte
+ windowEnd int
+ blockStart int // window index where current tokens start
+ byteAvailable bool // if true, still need to process window[index-1].
+
+ // queued output tokens
+ tokens tokens
+
+ // deflate state
+ length int
+ offset int
+ hash uint32
+ maxInsertIndex int
+ err error
+ ii uint16 // position of last match, intended to overflow to reset.
+
+ snap snappyEnc
+ hashMatch [maxMatchLength + minMatchLength]uint32
+}
+
+func (d *compressor) fillDeflate(b []byte) int {
+ if d.index >= 2*windowSize-(minMatchLength+maxMatchLength) {
+ // shift the window by windowSize
+ copy(d.window[:], d.window[windowSize:2*windowSize])
+ d.index -= windowSize
+ d.windowEnd -= windowSize
+ if d.blockStart >= windowSize {
+ d.blockStart -= windowSize
+ } else {
+ d.blockStart = math.MaxInt32
+ }
+ d.hashOffset += windowSize
+ if d.hashOffset > maxHashOffset {
+ delta := d.hashOffset - 1
+ d.hashOffset -= delta
+ d.chainHead -= delta
+ // Iterate over slices instead of arrays to avoid copying
+ // the entire table onto the stack (Issue #18625).
+ for i, v := range d.hashPrev[:] {
+ if int(v) > delta {
+ d.hashPrev[i] = uint32(int(v) - delta)
+ } else {
+ d.hashPrev[i] = 0
+ }
+ }
+ for i, v := range d.hashHead[:] {
+ if int(v) > delta {
+ d.hashHead[i] = uint32(int(v) - delta)
+ } else {
+ d.hashHead[i] = 0
+ }
+ }
+ }
+ }
+ n := copy(d.window[d.windowEnd:], b)
+ d.windowEnd += n
+ return n
+}
+
+func (d *compressor) writeBlock(tok tokens, index int, eof bool) error {
+ if index > 0 || eof {
+ var window []byte
+ if d.blockStart <= index {
+ window = d.window[d.blockStart:index]
+ }
+ d.blockStart = index
+ d.w.writeBlock(tok.tokens[:tok.n], eof, window)
+ return d.w.err
+ }
+ return nil
+}
+
+// writeBlockSkip writes the current block and uses the number of tokens
+// to determine if the block should be stored on no matches, or
+// only huffman encoded.
+func (d *compressor) writeBlockSkip(tok tokens, index int, eof bool) error {
+ if index > 0 || eof {
+ if d.blockStart <= index {
+ window := d.window[d.blockStart:index]
+ // If we removed less than a 64th of all literals
+ // we huffman compress the block.
+ if int(tok.n) > len(window)-int(tok.n>>6) {
+ d.w.writeBlockHuff(eof, window)
+ } else {
+ // Write a dynamic huffman block.
+ d.w.writeBlockDynamic(tok.tokens[:tok.n], eof, window)
+ }
+ } else {
+ d.w.writeBlock(tok.tokens[:tok.n], eof, nil)
+ }
+ d.blockStart = index
+ return d.w.err
+ }
+ return nil
+}
+
+// fillWindow will fill the current window with the supplied
+// dictionary and calculate all hashes.
+// This is much faster than doing a full encode.
+// Should only be used after a start/reset.
+func (d *compressor) fillWindow(b []byte) {
+ // Do not fill window if we are in store-only mode,
+ // use constant or Snappy compression.
+ switch d.compressionLevel.level {
+ case 0, 1, 2:
+ return
+ }
+ // If we are given too much, cut it.
+ if len(b) > windowSize {
+ b = b[len(b)-windowSize:]
+ }
+ // Add all to window.
+ n := copy(d.window[d.windowEnd:], b)
+
+ // Calculate 256 hashes at the time (more L1 cache hits)
+ loops := (n + 256 - minMatchLength) / 256
+ for j := 0; j < loops; j++ {
+ startindex := j * 256
+ end := startindex + 256 + minMatchLength - 1
+ if end > n {
+ end = n
+ }
+ tocheck := d.window[startindex:end]
+ dstSize := len(tocheck) - minMatchLength + 1
+
+ if dstSize <= 0 {
+ continue
+ }
+
+ dst := d.hashMatch[:dstSize]
+ d.bulkHasher(tocheck, dst)
+ var newH uint32
+ for i, val := range dst {
+ di := i + startindex
+ newH = val & hashMask
+ // Get previous value with the same hash.
+ // Our chain should point to the previous value.
+ d.hashPrev[di&windowMask] = d.hashHead[newH]
+ // Set the head of the hash chain to us.
+ d.hashHead[newH] = uint32(di + d.hashOffset)
+ }
+ d.hash = newH
+ }
+ // Update window information.
+ d.windowEnd += n
+ d.index = n
+}
+
+// Try to find a match starting at index whose length is greater than prevSize.
+// We only look at chainCount possibilities before giving up.
+// pos = d.index, prevHead = d.chainHead-d.hashOffset, prevLength=minMatchLength-1, lookahead
+func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead int) (length, offset int, ok bool) {
+ minMatchLook := maxMatchLength
+ if lookahead < minMatchLook {
+ minMatchLook = lookahead
+ }
+
+ win := d.window[0 : pos+minMatchLook]
+
+ // We quit when we get a match that's at least nice long
+ nice := len(win) - pos
+ if d.nice < nice {
+ nice = d.nice
+ }
+
+ // If we've got a match that's good enough, only look in 1/4 the chain.
+ tries := d.chain
+ length = prevLength
+ if length >= d.good {
+ tries >>= 2
+ }
+
+ wEnd := win[pos+length]
+ wPos := win[pos:]
+ minIndex := pos - windowSize
+
+ for i := prevHead; tries > 0; tries-- {
+ if wEnd == win[i+length] {
+ n := matchLen(win[i:], wPos, minMatchLook)
+
+ if n > length && (n > minMatchLength || pos-i <= 4096) {
+ length = n
+ offset = pos - i
+ ok = true
+ if n >= nice {
+ // The match is good enough that we don't try to find a better one.
+ break
+ }
+ wEnd = win[pos+n]
+ }
+ }
+ if i == minIndex {
+ // hashPrev[i & windowMask] has already been overwritten, so stop now.
+ break
+ }
+ i = int(d.hashPrev[i&windowMask]) - d.hashOffset
+ if i < minIndex || i < 0 {
+ break
+ }
+ }
+ return
+}
+
+// Try to find a match starting at index whose length is greater than prevSize.
+// We only look at chainCount possibilities before giving up.
+// pos = d.index, prevHead = d.chainHead-d.hashOffset, prevLength=minMatchLength-1, lookahead
+func (d *compressor) findMatchSSE(pos int, prevHead int, prevLength int, lookahead int) (length, offset int, ok bool) {
+ minMatchLook := maxMatchLength
+ if lookahead < minMatchLook {
+ minMatchLook = lookahead
+ }
+
+ win := d.window[0 : pos+minMatchLook]
+
+ // We quit when we get a match that's at least nice long
+ nice := len(win) - pos
+ if d.nice < nice {
+ nice = d.nice
+ }
+
+ // If we've got a match that's good enough, only look in 1/4 the chain.
+ tries := d.chain
+ length = prevLength
+ if length >= d.good {
+ tries >>= 2
+ }
+
+ wEnd := win[pos+length]
+ wPos := win[pos:]
+ minIndex := pos - windowSize
+
+ for i := prevHead; tries > 0; tries-- {
+ if wEnd == win[i+length] {
+ n := matchLenSSE4(win[i:], wPos, minMatchLook)
+
+ if n > length && (n > minMatchLength || pos-i <= 4096) {
+ length = n
+ offset = pos - i
+ ok = true
+ if n >= nice {
+ // The match is good enough that we don't try to find a better one.
+ break
+ }
+ wEnd = win[pos+n]
+ }
+ }
+ if i == minIndex {
+ // hashPrev[i & windowMask] has already been overwritten, so stop now.
+ break
+ }
+ i = int(d.hashPrev[i&windowMask]) - d.hashOffset
+ if i < minIndex || i < 0 {
+ break
+ }
+ }
+ return
+}
+
+func (d *compressor) writeStoredBlock(buf []byte) error {
+ if d.w.writeStoredHeader(len(buf), false); d.w.err != nil {
+ return d.w.err
+ }
+ d.w.writeBytes(buf)
+ return d.w.err
+}
+
+const hashmul = 0x1e35a7bd
+
+// hash4 returns a hash representation of the first 4 bytes
+// of the supplied slice.
+// The caller must ensure that len(b) >= 4.
+func hash4(b []byte) uint32 {
+ return ((uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24) * hashmul) >> (32 - hashBits)
+}
+
+// bulkHash4 will compute hashes using the same
+// algorithm as hash4
+func bulkHash4(b []byte, dst []uint32) {
+ if len(b) < minMatchLength {
+ return
+ }
+ hb := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+ dst[0] = (hb * hashmul) >> (32 - hashBits)
+ end := len(b) - minMatchLength + 1
+ for i := 1; i < end; i++ {
+ hb = (hb << 8) | uint32(b[i+3])
+ dst[i] = (hb * hashmul) >> (32 - hashBits)
+ }
+}
+
+// matchLen returns the number of matching bytes in a and b
+// up to length 'max'. Both slices must be at least 'max'
+// bytes in size.
+func matchLen(a, b []byte, max int) int {
+ a = a[:max]
+ b = b[:len(a)]
+ for i, av := range a {
+ if b[i] != av {
+ return i
+ }
+ }
+ return max
+}
+
+func (d *compressor) initDeflate() {
+ d.window = make([]byte, 2*windowSize)
+ d.hashOffset = 1
+ d.length = minMatchLength - 1
+ d.offset = 0
+ d.byteAvailable = false
+ d.index = 0
+ d.hash = 0
+ d.chainHead = -1
+ d.bulkHasher = bulkHash4
+ if useSSE42 {
+ d.bulkHasher = crc32sseAll
+ }
+}
+
+// Assumes that d.fastSkipHashing != skipNever,
+// otherwise use deflateLazy
+func (d *compressor) deflate() {
+
+ // Sanity enables additional runtime tests.
+ // It's intended to be used during development
+ // to supplement the currently ad-hoc unit tests.
+ const sanity = false
+
+ if d.windowEnd-d.index < minMatchLength+maxMatchLength && !d.sync {
+ return
+ }
+
+ d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+ if d.index < d.maxInsertIndex {
+ d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+ }
+
+ for {
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ lookahead := d.windowEnd - d.index
+ if lookahead < minMatchLength+maxMatchLength {
+ if !d.sync {
+ return
+ }
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ if lookahead == 0 {
+ if d.tokens.n > 0 {
+ if d.err = d.writeBlockSkip(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ return
+ }
+ }
+ if d.index < d.maxInsertIndex {
+ // Update the hash
+ d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+ ch := d.hashHead[d.hash&hashMask]
+ d.chainHead = int(ch)
+ d.hashPrev[d.index&windowMask] = ch
+ d.hashHead[d.hash&hashMask] = uint32(d.index + d.hashOffset)
+ }
+ d.length = minMatchLength - 1
+ d.offset = 0
+ minIndex := d.index - windowSize
+ if minIndex < 0 {
+ minIndex = 0
+ }
+
+ if d.chainHead-d.hashOffset >= minIndex && lookahead > minMatchLength-1 {
+ if newLength, newOffset, ok := d.findMatch(d.index, d.chainHead-d.hashOffset, minMatchLength-1, lookahead); ok {
+ d.length = newLength
+ d.offset = newOffset
+ }
+ }
+ if d.length >= minMatchLength {
+ d.ii = 0
+ // There was a match at the previous step, and the current match is
+ // not better. Output the previous match.
+ // "d.length-3" should NOT be "d.length-minMatchLength", since the format always assume 3
+ d.tokens.tokens[d.tokens.n] = matchToken(uint32(d.length-3), uint32(d.offset-minOffsetSize))
+ d.tokens.n++
+ // Insert in the hash table all strings up to the end of the match.
+ // index and index-1 are already inserted. If there is not enough
+ // lookahead, the last two strings are not inserted into the hash
+ // table.
+ if d.length <= d.fastSkipHashing {
+ var newIndex int
+ newIndex = d.index + d.length
+ // Calculate missing hashes
+ end := newIndex
+ if end > d.maxInsertIndex {
+ end = d.maxInsertIndex
+ }
+ end += minMatchLength - 1
+ startindex := d.index + 1
+ if startindex > d.maxInsertIndex {
+ startindex = d.maxInsertIndex
+ }
+ tocheck := d.window[startindex:end]
+ dstSize := len(tocheck) - minMatchLength + 1
+ if dstSize > 0 {
+ dst := d.hashMatch[:dstSize]
+ bulkHash4(tocheck, dst)
+ var newH uint32
+ for i, val := range dst {
+ di := i + startindex
+ newH = val & hashMask
+ // Get previous value with the same hash.
+ // Our chain should point to the previous value.
+ d.hashPrev[di&windowMask] = d.hashHead[newH]
+ // Set the head of the hash chain to us.
+ d.hashHead[newH] = uint32(di + d.hashOffset)
+ }
+ d.hash = newH
+ }
+ d.index = newIndex
+ } else {
+ // For matches this long, we don't bother inserting each individual
+ // item into the table.
+ d.index += d.length
+ if d.index < d.maxInsertIndex {
+ d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+ }
+ }
+ if d.tokens.n == maxFlateBlockTokens {
+ // The block includes the current character
+ if d.err = d.writeBlockSkip(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ } else {
+ d.ii++
+ end := d.index + int(d.ii>>uint(d.fastSkipHashing)) + 1
+ if end > d.windowEnd {
+ end = d.windowEnd
+ }
+ for i := d.index; i < end; i++ {
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[i]))
+ d.tokens.n++
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlockSkip(d.tokens, i+1, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ }
+ d.index = end
+ }
+ }
+}
+
+// deflateLazy is the same as deflate, but with d.fastSkipHashing == skipNever,
+// meaning it always has lazy matching on.
+func (d *compressor) deflateLazy() {
+ // Sanity enables additional runtime tests.
+ // It's intended to be used during development
+ // to supplement the currently ad-hoc unit tests.
+ const sanity = false
+
+ if d.windowEnd-d.index < minMatchLength+maxMatchLength && !d.sync {
+ return
+ }
+
+ d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+ if d.index < d.maxInsertIndex {
+ d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+ }
+
+ for {
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ lookahead := d.windowEnd - d.index
+ if lookahead < minMatchLength+maxMatchLength {
+ if !d.sync {
+ return
+ }
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ if lookahead == 0 {
+ // Flush current output block if any.
+ if d.byteAvailable {
+ // There is still one pending token that needs to be flushed
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ d.byteAvailable = false
+ }
+ if d.tokens.n > 0 {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ return
+ }
+ }
+ if d.index < d.maxInsertIndex {
+ // Update the hash
+ d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+ ch := d.hashHead[d.hash&hashMask]
+ d.chainHead = int(ch)
+ d.hashPrev[d.index&windowMask] = ch
+ d.hashHead[d.hash&hashMask] = uint32(d.index + d.hashOffset)
+ }
+ prevLength := d.length
+ prevOffset := d.offset
+ d.length = minMatchLength - 1
+ d.offset = 0
+ minIndex := d.index - windowSize
+ if minIndex < 0 {
+ minIndex = 0
+ }
+
+ if d.chainHead-d.hashOffset >= minIndex && lookahead > prevLength && prevLength < d.lazy {
+ if newLength, newOffset, ok := d.findMatch(d.index, d.chainHead-d.hashOffset, minMatchLength-1, lookahead); ok {
+ d.length = newLength
+ d.offset = newOffset
+ }
+ }
+ if prevLength >= minMatchLength && d.length <= prevLength {
+ // There was a match at the previous step, and the current match is
+ // not better. Output the previous match.
+ d.tokens.tokens[d.tokens.n] = matchToken(uint32(prevLength-3), uint32(prevOffset-minOffsetSize))
+ d.tokens.n++
+
+ // Insert in the hash table all strings up to the end of the match.
+ // index and index-1 are already inserted. If there is not enough
+ // lookahead, the last two strings are not inserted into the hash
+ // table.
+ var newIndex int
+ newIndex = d.index + prevLength - 1
+ // Calculate missing hashes
+ end := newIndex
+ if end > d.maxInsertIndex {
+ end = d.maxInsertIndex
+ }
+ end += minMatchLength - 1
+ startindex := d.index + 1
+ if startindex > d.maxInsertIndex {
+ startindex = d.maxInsertIndex
+ }
+ tocheck := d.window[startindex:end]
+ dstSize := len(tocheck) - minMatchLength + 1
+ if dstSize > 0 {
+ dst := d.hashMatch[:dstSize]
+ bulkHash4(tocheck, dst)
+ var newH uint32
+ for i, val := range dst {
+ di := i + startindex
+ newH = val & hashMask
+ // Get previous value with the same hash.
+ // Our chain should point to the previous value.
+ d.hashPrev[di&windowMask] = d.hashHead[newH]
+ // Set the head of the hash chain to us.
+ d.hashHead[newH] = uint32(di + d.hashOffset)
+ }
+ d.hash = newH
+ }
+
+ d.index = newIndex
+ d.byteAvailable = false
+ d.length = minMatchLength - 1
+ if d.tokens.n == maxFlateBlockTokens {
+ // The block includes the current character
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ } else {
+ // Reset, if we got a match this run.
+ if d.length >= minMatchLength {
+ d.ii = 0
+ }
+ // We have a byte waiting. Emit it.
+ if d.byteAvailable {
+ d.ii++
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ d.index++
+
+ // If we have a long run of no matches, skip additional bytes
+ // Resets when d.ii overflows after 64KB.
+ if d.ii > 31 {
+ n := int(d.ii >> 5)
+ for j := 0; j < n; j++ {
+ if d.index >= d.windowEnd-1 {
+ break
+ }
+
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ d.index++
+ }
+ // Flush last byte
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ d.byteAvailable = false
+ // d.length = minMatchLength - 1 // not needed, since d.ii is reset above, so it should never be > minMatchLength
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ }
+ } else {
+ d.index++
+ d.byteAvailable = true
+ }
+ }
+ }
+}
+
+// Assumes that d.fastSkipHashing != skipNever,
+// otherwise use deflateLazySSE
+func (d *compressor) deflateSSE() {
+
+ // Sanity enables additional runtime tests.
+ // It's intended to be used during development
+ // to supplement the currently ad-hoc unit tests.
+ const sanity = false
+
+ if d.windowEnd-d.index < minMatchLength+maxMatchLength && !d.sync {
+ return
+ }
+
+ d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+ if d.index < d.maxInsertIndex {
+ d.hash = crc32sse(d.window[d.index:d.index+minMatchLength]) & hashMask
+ }
+
+ for {
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ lookahead := d.windowEnd - d.index
+ if lookahead < minMatchLength+maxMatchLength {
+ if !d.sync {
+ return
+ }
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ if lookahead == 0 {
+ if d.tokens.n > 0 {
+ if d.err = d.writeBlockSkip(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ return
+ }
+ }
+ if d.index < d.maxInsertIndex {
+ // Update the hash
+ d.hash = crc32sse(d.window[d.index:d.index+minMatchLength]) & hashMask
+ ch := d.hashHead[d.hash]
+ d.chainHead = int(ch)
+ d.hashPrev[d.index&windowMask] = ch
+ d.hashHead[d.hash] = uint32(d.index + d.hashOffset)
+ }
+ d.length = minMatchLength - 1
+ d.offset = 0
+ minIndex := d.index - windowSize
+ if minIndex < 0 {
+ minIndex = 0
+ }
+
+ if d.chainHead-d.hashOffset >= minIndex && lookahead > minMatchLength-1 {
+ if newLength, newOffset, ok := d.findMatchSSE(d.index, d.chainHead-d.hashOffset, minMatchLength-1, lookahead); ok {
+ d.length = newLength
+ d.offset = newOffset
+ }
+ }
+ if d.length >= minMatchLength {
+ d.ii = 0
+ // There was a match at the previous step, and the current match is
+ // not better. Output the previous match.
+ // "d.length-3" should NOT be "d.length-minMatchLength", since the format always assume 3
+ d.tokens.tokens[d.tokens.n] = matchToken(uint32(d.length-3), uint32(d.offset-minOffsetSize))
+ d.tokens.n++
+ // Insert in the hash table all strings up to the end of the match.
+ // index and index-1 are already inserted. If there is not enough
+ // lookahead, the last two strings are not inserted into the hash
+ // table.
+ if d.length <= d.fastSkipHashing {
+ var newIndex int
+ newIndex = d.index + d.length
+ // Calculate missing hashes
+ end := newIndex
+ if end > d.maxInsertIndex {
+ end = d.maxInsertIndex
+ }
+ end += minMatchLength - 1
+ startindex := d.index + 1
+ if startindex > d.maxInsertIndex {
+ startindex = d.maxInsertIndex
+ }
+ tocheck := d.window[startindex:end]
+ dstSize := len(tocheck) - minMatchLength + 1
+ if dstSize > 0 {
+ dst := d.hashMatch[:dstSize]
+
+ crc32sseAll(tocheck, dst)
+ var newH uint32
+ for i, val := range dst {
+ di := i + startindex
+ newH = val & hashMask
+ // Get previous value with the same hash.
+ // Our chain should point to the previous value.
+ d.hashPrev[di&windowMask] = d.hashHead[newH]
+ // Set the head of the hash chain to us.
+ d.hashHead[newH] = uint32(di + d.hashOffset)
+ }
+ d.hash = newH
+ }
+ d.index = newIndex
+ } else {
+ // For matches this long, we don't bother inserting each individual
+ // item into the table.
+ d.index += d.length
+ if d.index < d.maxInsertIndex {
+ d.hash = crc32sse(d.window[d.index:d.index+minMatchLength]) & hashMask
+ }
+ }
+ if d.tokens.n == maxFlateBlockTokens {
+ // The block includes the current character
+ if d.err = d.writeBlockSkip(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ } else {
+ d.ii++
+ end := d.index + int(d.ii>>5) + 1
+ if end > d.windowEnd {
+ end = d.windowEnd
+ }
+ for i := d.index; i < end; i++ {
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[i]))
+ d.tokens.n++
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlockSkip(d.tokens, i+1, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ }
+ d.index = end
+ }
+ }
+}
+
+// deflateLazy is the same as deflate, but with d.fastSkipHashing == skipNever,
+// meaning it always has lazy matching on.
+func (d *compressor) deflateLazySSE() {
+ // Sanity enables additional runtime tests.
+ // It's intended to be used during development
+ // to supplement the currently ad-hoc unit tests.
+ const sanity = false
+
+ if d.windowEnd-d.index < minMatchLength+maxMatchLength && !d.sync {
+ return
+ }
+
+ d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+ if d.index < d.maxInsertIndex {
+ d.hash = crc32sse(d.window[d.index:d.index+minMatchLength]) & hashMask
+ }
+
+ for {
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ lookahead := d.windowEnd - d.index
+ if lookahead < minMatchLength+maxMatchLength {
+ if !d.sync {
+ return
+ }
+ if sanity && d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ if lookahead == 0 {
+ // Flush current output block if any.
+ if d.byteAvailable {
+ // There is still one pending token that needs to be flushed
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ d.byteAvailable = false
+ }
+ if d.tokens.n > 0 {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ return
+ }
+ }
+ if d.index < d.maxInsertIndex {
+ // Update the hash
+ d.hash = crc32sse(d.window[d.index:d.index+minMatchLength]) & hashMask
+ ch := d.hashHead[d.hash]
+ d.chainHead = int(ch)
+ d.hashPrev[d.index&windowMask] = ch
+ d.hashHead[d.hash] = uint32(d.index + d.hashOffset)
+ }
+ prevLength := d.length
+ prevOffset := d.offset
+ d.length = minMatchLength - 1
+ d.offset = 0
+ minIndex := d.index - windowSize
+ if minIndex < 0 {
+ minIndex = 0
+ }
+
+ if d.chainHead-d.hashOffset >= minIndex && lookahead > prevLength && prevLength < d.lazy {
+ if newLength, newOffset, ok := d.findMatchSSE(d.index, d.chainHead-d.hashOffset, minMatchLength-1, lookahead); ok {
+ d.length = newLength
+ d.offset = newOffset
+ }
+ }
+ if prevLength >= minMatchLength && d.length <= prevLength {
+ // There was a match at the previous step, and the current match is
+ // not better. Output the previous match.
+ d.tokens.tokens[d.tokens.n] = matchToken(uint32(prevLength-3), uint32(prevOffset-minOffsetSize))
+ d.tokens.n++
+
+ // Insert in the hash table all strings up to the end of the match.
+ // index and index-1 are already inserted. If there is not enough
+ // lookahead, the last two strings are not inserted into the hash
+ // table.
+ var newIndex int
+ newIndex = d.index + prevLength - 1
+ // Calculate missing hashes
+ end := newIndex
+ if end > d.maxInsertIndex {
+ end = d.maxInsertIndex
+ }
+ end += minMatchLength - 1
+ startindex := d.index + 1
+ if startindex > d.maxInsertIndex {
+ startindex = d.maxInsertIndex
+ }
+ tocheck := d.window[startindex:end]
+ dstSize := len(tocheck) - minMatchLength + 1
+ if dstSize > 0 {
+ dst := d.hashMatch[:dstSize]
+ crc32sseAll(tocheck, dst)
+ var newH uint32
+ for i, val := range dst {
+ di := i + startindex
+ newH = val & hashMask
+ // Get previous value with the same hash.
+ // Our chain should point to the previous value.
+ d.hashPrev[di&windowMask] = d.hashHead[newH]
+ // Set the head of the hash chain to us.
+ d.hashHead[newH] = uint32(di + d.hashOffset)
+ }
+ d.hash = newH
+ }
+
+ d.index = newIndex
+ d.byteAvailable = false
+ d.length = minMatchLength - 1
+ if d.tokens.n == maxFlateBlockTokens {
+ // The block includes the current character
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ } else {
+ // Reset, if we got a match this run.
+ if d.length >= minMatchLength {
+ d.ii = 0
+ }
+ // We have a byte waiting. Emit it.
+ if d.byteAvailable {
+ d.ii++
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ d.index++
+
+ // If we have a long run of no matches, skip additional bytes
+ // Resets when d.ii overflows after 64KB.
+ if d.ii > 31 {
+ n := int(d.ii >> 6)
+ for j := 0; j < n; j++ {
+ if d.index >= d.windowEnd-1 {
+ break
+ }
+
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ d.index++
+ }
+ // Flush last byte
+ d.tokens.tokens[d.tokens.n] = literalToken(uint32(d.window[d.index-1]))
+ d.tokens.n++
+ d.byteAvailable = false
+ // d.length = minMatchLength - 1 // not needed, since d.ii is reset above, so it should never be > minMatchLength
+ if d.tokens.n == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.tokens.n = 0
+ }
+ }
+ } else {
+ d.index++
+ d.byteAvailable = true
+ }
+ }
+ }
+}
+
+func (d *compressor) store() {
+ if d.windowEnd > 0 && (d.windowEnd == maxStoreBlockSize || d.sync) {
+ d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+ d.windowEnd = 0
+ }
+}
+
+// fillWindow will fill the buffer with data for huffman-only compression.
+// The number of bytes copied is returned.
+func (d *compressor) fillBlock(b []byte) int {
+ n := copy(d.window[d.windowEnd:], b)
+ d.windowEnd += n
+ return n
+}
+
+// storeHuff will compress and store the currently added data,
+// if enough has been accumulated or we at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) storeHuff() {
+ if d.windowEnd < len(d.window) && !d.sync || d.windowEnd == 0 {
+ return
+ }
+ d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+ d.err = d.w.err
+ d.windowEnd = 0
+}
+
+// storeHuff will compress and store the currently added data,
+// if enough has been accumulated or we at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) storeSnappy() {
+ // We only compress if we have maxStoreBlockSize.
+ if d.windowEnd < maxStoreBlockSize {
+ if !d.sync {
+ return
+ }
+ // Handle extremely small sizes.
+ if d.windowEnd < 128 {
+ if d.windowEnd == 0 {
+ return
+ }
+ if d.windowEnd <= 32 {
+ d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+ d.tokens.n = 0
+ d.windowEnd = 0
+ } else {
+ d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+ d.err = d.w.err
+ }
+ d.tokens.n = 0
+ d.windowEnd = 0
+ d.snap.Reset()
+ return
+ }
+ }
+
+ d.snap.Encode(&d.tokens, d.window[:d.windowEnd])
+ // If we made zero matches, store the block as is.
+ if int(d.tokens.n) == d.windowEnd {
+ d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+ // If we removed less than 1/16th, huffman compress the block.
+ } else if int(d.tokens.n) > d.windowEnd-(d.windowEnd>>4) {
+ d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+ d.err = d.w.err
+ } else {
+ d.w.writeBlockDynamic(d.tokens.tokens[:d.tokens.n], false, d.window[:d.windowEnd])
+ d.err = d.w.err
+ }
+ d.tokens.n = 0
+ d.windowEnd = 0
+}
+
+// write will add input byte to the stream.
+// Unless an error occurs all bytes will be consumed.
+func (d *compressor) write(b []byte) (n int, err error) {
+ if d.err != nil {
+ return 0, d.err
+ }
+ n = len(b)
+ for len(b) > 0 {
+ d.step(d)
+ b = b[d.fill(d, b):]
+ if d.err != nil {
+ return 0, d.err
+ }
+ }
+ return n, d.err
+}
+
+func (d *compressor) syncFlush() error {
+ d.sync = true
+ if d.err != nil {
+ return d.err
+ }
+ d.step(d)
+ if d.err == nil {
+ d.w.writeStoredHeader(0, false)
+ d.w.flush()
+ d.err = d.w.err
+ }
+ d.sync = false
+ return d.err
+}
+
+func (d *compressor) init(w io.Writer, level int) (err error) {
+ d.w = newHuffmanBitWriter(w)
+
+ switch {
+ case level == NoCompression:
+ d.window = make([]byte, maxStoreBlockSize)
+ d.fill = (*compressor).fillBlock
+ d.step = (*compressor).store
+ case level == ConstantCompression:
+ d.window = make([]byte, maxStoreBlockSize)
+ d.fill = (*compressor).fillBlock
+ d.step = (*compressor).storeHuff
+ case level >= 1 && level <= 4:
+ d.snap = newSnappy(level)
+ d.window = make([]byte, maxStoreBlockSize)
+ d.fill = (*compressor).fillBlock
+ d.step = (*compressor).storeSnappy
+ case level == DefaultCompression:
+ level = 5
+ fallthrough
+ case 5 <= level && level <= 9:
+ d.compressionLevel = levels[level]
+ d.initDeflate()
+ d.fill = (*compressor).fillDeflate
+ if d.fastSkipHashing == skipNever {
+ if useSSE42 {
+ d.step = (*compressor).deflateLazySSE
+ } else {
+ d.step = (*compressor).deflateLazy
+ }
+ } else {
+ if useSSE42 {
+ d.step = (*compressor).deflateSSE
+ } else {
+ d.step = (*compressor).deflate
+
+ }
+ }
+ default:
+ return fmt.Errorf("flate: invalid compression level %d: want value in range [-2, 9]", level)
+ }
+ return nil
+}
+
+// reset the state of the compressor.
+func (d *compressor) reset(w io.Writer) {
+ d.w.reset(w)
+ d.sync = false
+ d.err = nil
+ // We only need to reset a few things for Snappy.
+ if d.snap != nil {
+ d.snap.Reset()
+ d.windowEnd = 0
+ d.tokens.n = 0
+ return
+ }
+ switch d.compressionLevel.chain {
+ case 0:
+ // level was NoCompression or ConstantCompresssion.
+ d.windowEnd = 0
+ default:
+ d.chainHead = -1
+ for i := range d.hashHead {
+ d.hashHead[i] = 0
+ }
+ for i := range d.hashPrev {
+ d.hashPrev[i] = 0
+ }
+ d.hashOffset = 1
+ d.index, d.windowEnd = 0, 0
+ d.blockStart, d.byteAvailable = 0, false
+ d.tokens.n = 0
+ d.length = minMatchLength - 1
+ d.offset = 0
+ d.hash = 0
+ d.ii = 0
+ d.maxInsertIndex = 0
+ }
+}
+
+func (d *compressor) close() error {
+ if d.err != nil {
+ return d.err
+ }
+ d.sync = true
+ d.step(d)
+ if d.err != nil {
+ return d.err
+ }
+ if d.w.writeStoredHeader(0, true); d.w.err != nil {
+ return d.w.err
+ }
+ d.w.flush()
+ return d.w.err
+}
+
+// NewWriter returns a new Writer compressing data at the given level.
+// Following zlib, levels range from 1 (BestSpeed) to 9 (BestCompression);
+// higher levels typically run slower but compress more.
+// Level 0 (NoCompression) does not attempt any compression; it only adds the
+// necessary DEFLATE framing.
+// Level -1 (DefaultCompression) uses the default compression level.
+// Level -2 (ConstantCompression) will use Huffman compression only, giving
+// a very fast compression for all types of input, but sacrificing considerable
+// compression efficiency.
+//
+// If level is in the range [-2, 9] then the error returned will be nil.
+// Otherwise the error returned will be non-nil.
+func NewWriter(w io.Writer, level int) (*Writer, error) {
+ var dw Writer
+ if err := dw.d.init(w, level); err != nil {
+ return nil, err
+ }
+ return &dw, nil
+}
+
+// NewWriterDict is like NewWriter but initializes the new
+// Writer with a preset dictionary. The returned Writer behaves
+// as if the dictionary had been written to it without producing
+// any compressed output. The compressed data written to w
+// can only be decompressed by a Reader initialized with the
+// same dictionary.
+func NewWriterDict(w io.Writer, level int, dict []byte) (*Writer, error) {
+ dw := &dictWriter{w}
+ zw, err := NewWriter(dw, level)
+ if err != nil {
+ return nil, err
+ }
+ zw.d.fillWindow(dict)
+ zw.dict = append(zw.dict, dict...) // duplicate dictionary for Reset method.
+ return zw, err
+}
+
+type dictWriter struct {
+ w io.Writer
+}
+
+func (w *dictWriter) Write(b []byte) (n int, err error) {
+ return w.w.Write(b)
+}
+
+// A Writer takes data written to it and writes the compressed
+// form of that data to an underlying writer (see NewWriter).
+type Writer struct {
+ d compressor
+ dict []byte
+}
+
+// Write writes data to w, which will eventually write the
+// compressed form of data to its underlying writer.
+func (w *Writer) Write(data []byte) (n int, err error) {
+ return w.d.write(data)
+}
+
+// Flush flushes any pending data to the underlying writer.
+// It is useful mainly in compressed network protocols, to ensure that
+// a remote reader has enough data to reconstruct a packet.
+// Flush does not return until the data has been written.
+// Calling Flush when there is no pending data still causes the Writer
+// to emit a sync marker of at least 4 bytes.
+// If the underlying writer returns an error, Flush returns that error.
+//
+// In the terminology of the zlib library, Flush is equivalent to Z_SYNC_FLUSH.
+func (w *Writer) Flush() error {
+ // For more about flushing:
+ // http://www.bolet.org/~pornin/deflate-flush.html
+ return w.d.syncFlush()
+}
+
+// Close flushes and closes the writer.
+func (w *Writer) Close() error {
+ return w.d.close()
+}
+
+// Reset discards the writer's state and makes it equivalent to
+// the result of NewWriter or NewWriterDict called with dst
+// and w's level and dictionary.
+func (w *Writer) Reset(dst io.Writer) {
+ if dw, ok := w.d.w.writer.(*dictWriter); ok {
+ // w was created with NewWriterDict
+ dw.w = dst
+ w.d.reset(dw)
+ w.d.fillWindow(w.dict)
+ } else {
+ // w was created with NewWriter
+ w.d.reset(dst)
+ }
+}
+
+// ResetDict discards the writer's state and makes it equivalent to
+// the result of NewWriter or NewWriterDict called with dst
+// and w's level, but sets a specific dictionary.
+func (w *Writer) ResetDict(dst io.Writer, dict []byte) {
+ w.dict = dict
+ w.d.reset(dst)
+ w.d.fillWindow(w.dict)
+}
diff --git a/vendor/github.com/klauspost/compress/flate/dict_decoder.go b/vendor/github.com/klauspost/compress/flate/dict_decoder.go
new file mode 100644
index 000000000..71c75a065
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/dict_decoder.go
@@ -0,0 +1,184 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// dictDecoder implements the LZ77 sliding dictionary as used in decompression.
+// LZ77 decompresses data through sequences of two forms of commands:
+//
+// * Literal insertions: Runs of one or more symbols are inserted into the data
+// stream as is. This is accomplished through the writeByte method for a
+// single symbol, or combinations of writeSlice/writeMark for multiple symbols.
+// Any valid stream must start with a literal insertion if no preset dictionary
+// is used.
+//
+// * Backward copies: Runs of one or more symbols are copied from previously
+// emitted data. Backward copies come as the tuple (dist, length) where dist
+// determines how far back in the stream to copy from and length determines how
+// many bytes to copy. Note that it is valid for the length to be greater than
+// the distance. Since LZ77 uses forward copies, that situation is used to
+// perform a form of run-length encoding on repeated runs of symbols.
+// The writeCopy and tryWriteCopy are used to implement this command.
+//
+// For performance reasons, this implementation performs little to no sanity
+// checks about the arguments. As such, the invariants documented for each
+// method call must be respected.
+type dictDecoder struct {
+ hist []byte // Sliding window history
+
+ // Invariant: 0 <= rdPos <= wrPos <= len(hist)
+ wrPos int // Current output position in buffer
+ rdPos int // Have emitted hist[:rdPos] already
+ full bool // Has a full window length been written yet?
+}
+
+// init initializes dictDecoder to have a sliding window dictionary of the given
+// size. If a preset dict is provided, it will initialize the dictionary with
+// the contents of dict.
+func (dd *dictDecoder) init(size int, dict []byte) {
+ *dd = dictDecoder{hist: dd.hist}
+
+ if cap(dd.hist) < size {
+ dd.hist = make([]byte, size)
+ }
+ dd.hist = dd.hist[:size]
+
+ if len(dict) > len(dd.hist) {
+ dict = dict[len(dict)-len(dd.hist):]
+ }
+ dd.wrPos = copy(dd.hist, dict)
+ if dd.wrPos == len(dd.hist) {
+ dd.wrPos = 0
+ dd.full = true
+ }
+ dd.rdPos = dd.wrPos
+}
+
+// histSize reports the total amount of historical data in the dictionary.
+func (dd *dictDecoder) histSize() int {
+ if dd.full {
+ return len(dd.hist)
+ }
+ return dd.wrPos
+}
+
+// availRead reports the number of bytes that can be flushed by readFlush.
+func (dd *dictDecoder) availRead() int {
+ return dd.wrPos - dd.rdPos
+}
+
+// availWrite reports the available amount of output buffer space.
+func (dd *dictDecoder) availWrite() int {
+ return len(dd.hist) - dd.wrPos
+}
+
+// writeSlice returns a slice of the available buffer to write data to.
+//
+// This invariant will be kept: len(s) <= availWrite()
+func (dd *dictDecoder) writeSlice() []byte {
+ return dd.hist[dd.wrPos:]
+}
+
+// writeMark advances the writer pointer by cnt.
+//
+// This invariant must be kept: 0 <= cnt <= availWrite()
+func (dd *dictDecoder) writeMark(cnt int) {
+ dd.wrPos += cnt
+}
+
+// writeByte writes a single byte to the dictionary.
+//
+// This invariant must be kept: 0 < availWrite()
+func (dd *dictDecoder) writeByte(c byte) {
+ dd.hist[dd.wrPos] = c
+ dd.wrPos++
+}
+
+// writeCopy copies a string at a given (dist, length) to the output.
+// This returns the number of bytes copied and may be less than the requested
+// length if the available space in the output buffer is too small.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) writeCopy(dist, length int) int {
+ dstBase := dd.wrPos
+ dstPos := dstBase
+ srcPos := dstPos - dist
+ endPos := dstPos + length
+ if endPos > len(dd.hist) {
+ endPos = len(dd.hist)
+ }
+
+ // Copy non-overlapping section after destination position.
+ //
+ // This section is non-overlapping in that the copy length for this section
+ // is always less than or equal to the backwards distance. This can occur
+ // if a distance refers to data that wraps-around in the buffer.
+ // Thus, a backwards copy is performed here; that is, the exact bytes in
+ // the source prior to the copy is placed in the destination.
+ if srcPos < 0 {
+ srcPos += len(dd.hist)
+ dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:])
+ srcPos = 0
+ }
+
+ // Copy possibly overlapping section before destination position.
+ //
+ // This section can overlap if the copy length for this section is larger
+ // than the backwards distance. This is allowed by LZ77 so that repeated
+ // strings can be succinctly represented using (dist, length) pairs.
+ // Thus, a forwards copy is performed here; that is, the bytes copied is
+ // possibly dependent on the resulting bytes in the destination as the copy
+ // progresses along. This is functionally equivalent to the following:
+ //
+ // for i := 0; i < endPos-dstPos; i++ {
+ // dd.hist[dstPos+i] = dd.hist[srcPos+i]
+ // }
+ // dstPos = endPos
+ //
+ for dstPos < endPos {
+ dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+ }
+
+ dd.wrPos = dstPos
+ return dstPos - dstBase
+}
+
+// tryWriteCopy tries to copy a string at a given (distance, length) to the
+// output. This specialized version is optimized for short distances.
+//
+// This method is designed to be inlined for performance reasons.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) tryWriteCopy(dist, length int) int {
+ dstPos := dd.wrPos
+ endPos := dstPos + length
+ if dstPos < dist || endPos > len(dd.hist) {
+ return 0
+ }
+ dstBase := dstPos
+ srcPos := dstPos - dist
+
+ // Copy possibly overlapping section before destination position.
+loop:
+ dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+ if dstPos < endPos {
+ goto loop // Avoid for-loop so that this function can be inlined
+ }
+
+ dd.wrPos = dstPos
+ return dstPos - dstBase
+}
+
+// readFlush returns a slice of the historical buffer that is ready to be
+// emitted to the user. The data returned by readFlush must be fully consumed
+// before calling any other dictDecoder methods.
+func (dd *dictDecoder) readFlush() []byte {
+ toRead := dd.hist[dd.rdPos:dd.wrPos]
+ dd.rdPos = dd.wrPos
+ if dd.wrPos == len(dd.hist) {
+ dd.wrPos, dd.rdPos = 0, 0
+ dd.full = true
+ }
+ return toRead
+}
diff --git a/vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go b/vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go
new file mode 100644
index 000000000..f9b2a699a
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/huffman_bit_writer.go
@@ -0,0 +1,701 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+ "io"
+)
+
+const (
+ // The largest offset code.
+ offsetCodeCount = 30
+
+ // The special code used to mark the end of a block.
+ endBlockMarker = 256
+
+ // The first length code.
+ lengthCodesStart = 257
+
+ // The number of codegen codes.
+ codegenCodeCount = 19
+ badCode = 255
+
+ // bufferFlushSize indicates the buffer size
+ // after which bytes are flushed to the writer.
+ // Should preferably be a multiple of 6, since
+ // we accumulate 6 bytes between writes to the buffer.
+ bufferFlushSize = 240
+
+ // bufferSize is the actual output byte buffer size.
+ // It must have additional headroom for a flush
+ // which can contain up to 8 bytes.
+ bufferSize = bufferFlushSize + 8
+)
+
+// The number of extra bits needed by length code X - LENGTH_CODES_START.
+var lengthExtraBits = []int8{
+ /* 257 */ 0, 0, 0,
+ /* 260 */ 0, 0, 0, 0, 0, 1, 1, 1, 1, 2,
+ /* 270 */ 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
+ /* 280 */ 4, 5, 5, 5, 5, 0,
+}
+
+// The length indicated by length code X - LENGTH_CODES_START.
+var lengthBase = []uint32{
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 10,
+ 12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
+ 64, 80, 96, 112, 128, 160, 192, 224, 255,
+}
+
+// offset code word extra bits.
+var offsetExtraBits = []int8{
+ 0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
+ 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
+ 9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
+ /* extended window */
+ 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20,
+}
+
+var offsetBase = []uint32{
+ /* normal deflate */
+ 0x000000, 0x000001, 0x000002, 0x000003, 0x000004,
+ 0x000006, 0x000008, 0x00000c, 0x000010, 0x000018,
+ 0x000020, 0x000030, 0x000040, 0x000060, 0x000080,
+ 0x0000c0, 0x000100, 0x000180, 0x000200, 0x000300,
+ 0x000400, 0x000600, 0x000800, 0x000c00, 0x001000,
+ 0x001800, 0x002000, 0x003000, 0x004000, 0x006000,
+
+ /* extended window */
+ 0x008000, 0x00c000, 0x010000, 0x018000, 0x020000,
+ 0x030000, 0x040000, 0x060000, 0x080000, 0x0c0000,
+ 0x100000, 0x180000, 0x200000, 0x300000,
+}
+
+// The odd order in which the codegen code sizes are written.
+var codegenOrder = []uint32{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+type huffmanBitWriter struct {
+ // writer is the underlying writer.
+ // Do not use it directly; use the write method, which ensures
+ // that Write errors are sticky.
+ writer io.Writer
+
+ // Data waiting to be written is bytes[0:nbytes]
+ // and then the low nbits of bits.
+ bits uint64
+ nbits uint
+ bytes [bufferSize]byte
+ codegenFreq [codegenCodeCount]int32
+ nbytes int
+ literalFreq []int32
+ offsetFreq []int32
+ codegen []uint8
+ literalEncoding *huffmanEncoder
+ offsetEncoding *huffmanEncoder
+ codegenEncoding *huffmanEncoder
+ err error
+}
+
+func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
+ return &huffmanBitWriter{
+ writer: w,
+ literalFreq: make([]int32, maxNumLit),
+ offsetFreq: make([]int32, offsetCodeCount),
+ codegen: make([]uint8, maxNumLit+offsetCodeCount+1),
+ literalEncoding: newHuffmanEncoder(maxNumLit),
+ codegenEncoding: newHuffmanEncoder(codegenCodeCount),
+ offsetEncoding: newHuffmanEncoder(offsetCodeCount),
+ }
+}
+
+func (w *huffmanBitWriter) reset(writer io.Writer) {
+ w.writer = writer
+ w.bits, w.nbits, w.nbytes, w.err = 0, 0, 0, nil
+ w.bytes = [bufferSize]byte{}
+}
+
+func (w *huffmanBitWriter) flush() {
+ if w.err != nil {
+ w.nbits = 0
+ return
+ }
+ n := w.nbytes
+ for w.nbits != 0 {
+ w.bytes[n] = byte(w.bits)
+ w.bits >>= 8
+ if w.nbits > 8 { // Avoid underflow
+ w.nbits -= 8
+ } else {
+ w.nbits = 0
+ }
+ n++
+ }
+ w.bits = 0
+ w.write(w.bytes[:n])
+ w.nbytes = 0
+}
+
+func (w *huffmanBitWriter) write(b []byte) {
+ if w.err != nil {
+ return
+ }
+ _, w.err = w.writer.Write(b)
+}
+
+func (w *huffmanBitWriter) writeBits(b int32, nb uint) {
+ if w.err != nil {
+ return
+ }
+ w.bits |= uint64(b) << w.nbits
+ w.nbits += nb
+ if w.nbits >= 48 {
+ bits := w.bits
+ w.bits >>= 48
+ w.nbits -= 48
+ n := w.nbytes
+ bytes := w.bytes[n : n+6]
+ bytes[0] = byte(bits)
+ bytes[1] = byte(bits >> 8)
+ bytes[2] = byte(bits >> 16)
+ bytes[3] = byte(bits >> 24)
+ bytes[4] = byte(bits >> 32)
+ bytes[5] = byte(bits >> 40)
+ n += 6
+ if n >= bufferFlushSize {
+ w.write(w.bytes[:n])
+ n = 0
+ }
+ w.nbytes = n
+ }
+}
+
+func (w *huffmanBitWriter) writeBytes(bytes []byte) {
+ if w.err != nil {
+ return
+ }
+ n := w.nbytes
+ if w.nbits&7 != 0 {
+ w.err = InternalError("writeBytes with unfinished bits")
+ return
+ }
+ for w.nbits != 0 {
+ w.bytes[n] = byte(w.bits)
+ w.bits >>= 8
+ w.nbits -= 8
+ n++
+ }
+ if n != 0 {
+ w.write(w.bytes[:n])
+ }
+ w.nbytes = 0
+ w.write(bytes)
+}
+
+// RFC 1951 3.2.7 specifies a special run-length encoding for specifying
+// the literal and offset lengths arrays (which are concatenated into a single
+// array). This method generates that run-length encoding.
+//
+// The result is written into the codegen array, and the frequencies
+// of each code is written into the codegenFreq array.
+// Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
+// information. Code badCode is an end marker
+//
+// numLiterals The number of literals in literalEncoding
+// numOffsets The number of offsets in offsetEncoding
+// litenc, offenc The literal and offset encoder to use
+func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int, litEnc, offEnc *huffmanEncoder) {
+ for i := range w.codegenFreq {
+ w.codegenFreq[i] = 0
+ }
+ // Note that we are using codegen both as a temporary variable for holding
+ // a copy of the frequencies, and as the place where we put the result.
+ // This is fine because the output is always shorter than the input used
+ // so far.
+ codegen := w.codegen // cache
+ // Copy the concatenated code sizes to codegen. Put a marker at the end.
+ cgnl := codegen[:numLiterals]
+ for i := range cgnl {
+ cgnl[i] = uint8(litEnc.codes[i].len)
+ }
+
+ cgnl = codegen[numLiterals : numLiterals+numOffsets]
+ for i := range cgnl {
+ cgnl[i] = uint8(offEnc.codes[i].len)
+ }
+ codegen[numLiterals+numOffsets] = badCode
+
+ size := codegen[0]
+ count := 1
+ outIndex := 0
+ for inIndex := 1; size != badCode; inIndex++ {
+ // INVARIANT: We have seen "count" copies of size that have not yet
+ // had output generated for them.
+ nextSize := codegen[inIndex]
+ if nextSize == size {
+ count++
+ continue
+ }
+ // We need to generate codegen indicating "count" of size.
+ if size != 0 {
+ codegen[outIndex] = size
+ outIndex++
+ w.codegenFreq[size]++
+ count--
+ for count >= 3 {
+ n := 6
+ if n > count {
+ n = count
+ }
+ codegen[outIndex] = 16
+ outIndex++
+ codegen[outIndex] = uint8(n - 3)
+ outIndex++
+ w.codegenFreq[16]++
+ count -= n
+ }
+ } else {
+ for count >= 11 {
+ n := 138
+ if n > count {
+ n = count
+ }
+ codegen[outIndex] = 18
+ outIndex++
+ codegen[outIndex] = uint8(n - 11)
+ outIndex++
+ w.codegenFreq[18]++
+ count -= n
+ }
+ if count >= 3 {
+ // count >= 3 && count <= 10
+ codegen[outIndex] = 17
+ outIndex++
+ codegen[outIndex] = uint8(count - 3)
+ outIndex++
+ w.codegenFreq[17]++
+ count = 0
+ }
+ }
+ count--
+ for ; count >= 0; count-- {
+ codegen[outIndex] = size
+ outIndex++
+ w.codegenFreq[size]++
+ }
+ // Set up invariant for next time through the loop.
+ size = nextSize
+ count = 1
+ }
+ // Marker indicating the end of the codegen.
+ codegen[outIndex] = badCode
+}
+
+// dynamicSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) dynamicSize(litEnc, offEnc *huffmanEncoder, extraBits int) (size, numCodegens int) {
+ numCodegens = len(w.codegenFreq)
+ for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
+ numCodegens--
+ }
+ header := 3 + 5 + 5 + 4 + (3 * numCodegens) +
+ w.codegenEncoding.bitLength(w.codegenFreq[:]) +
+ int(w.codegenFreq[16])*2 +
+ int(w.codegenFreq[17])*3 +
+ int(w.codegenFreq[18])*7
+ size = header +
+ litEnc.bitLength(w.literalFreq) +
+ offEnc.bitLength(w.offsetFreq) +
+ extraBits
+
+ return size, numCodegens
+}
+
+// fixedSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) fixedSize(extraBits int) int {
+ return 3 +
+ fixedLiteralEncoding.bitLength(w.literalFreq) +
+ fixedOffsetEncoding.bitLength(w.offsetFreq) +
+ extraBits
+}
+
+// storedSize calculates the stored size, including header.
+// The function returns the size in bits and whether the block
+// fits inside a single block.
+func (w *huffmanBitWriter) storedSize(in []byte) (int, bool) {
+ if in == nil {
+ return 0, false
+ }
+ if len(in) <= maxStoreBlockSize {
+ return (len(in) + 5) * 8, true
+ }
+ return 0, false
+}
+
+func (w *huffmanBitWriter) writeCode(c hcode) {
+ if w.err != nil {
+ return
+ }
+ w.bits |= uint64(c.code) << w.nbits
+ w.nbits += uint(c.len)
+ if w.nbits >= 48 {
+ bits := w.bits
+ w.bits >>= 48
+ w.nbits -= 48
+ n := w.nbytes
+ bytes := w.bytes[n : n+6]
+ bytes[0] = byte(bits)
+ bytes[1] = byte(bits >> 8)
+ bytes[2] = byte(bits >> 16)
+ bytes[3] = byte(bits >> 24)
+ bytes[4] = byte(bits >> 32)
+ bytes[5] = byte(bits >> 40)
+ n += 6
+ if n >= bufferFlushSize {
+ w.write(w.bytes[:n])
+ n = 0
+ }
+ w.nbytes = n
+ }
+}
+
+// Write the header of a dynamic Huffman block to the output stream.
+//
+// numLiterals The number of literals specified in codegen
+// numOffsets The number of offsets specified in codegen
+// numCodegens The number of codegens used in codegen
+func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, numCodegens int, isEof bool) {
+ if w.err != nil {
+ return
+ }
+ var firstBits int32 = 4
+ if isEof {
+ firstBits = 5
+ }
+ w.writeBits(firstBits, 3)
+ w.writeBits(int32(numLiterals-257), 5)
+ w.writeBits(int32(numOffsets-1), 5)
+ w.writeBits(int32(numCodegens-4), 4)
+
+ for i := 0; i < numCodegens; i++ {
+ value := uint(w.codegenEncoding.codes[codegenOrder[i]].len)
+ w.writeBits(int32(value), 3)
+ }
+
+ i := 0
+ for {
+ var codeWord int = int(w.codegen[i])
+ i++
+ if codeWord == badCode {
+ break
+ }
+ w.writeCode(w.codegenEncoding.codes[uint32(codeWord)])
+
+ switch codeWord {
+ case 16:
+ w.writeBits(int32(w.codegen[i]), 2)
+ i++
+ break
+ case 17:
+ w.writeBits(int32(w.codegen[i]), 3)
+ i++
+ break
+ case 18:
+ w.writeBits(int32(w.codegen[i]), 7)
+ i++
+ break
+ }
+ }
+}
+
+func (w *huffmanBitWriter) writeStoredHeader(length int, isEof bool) {
+ if w.err != nil {
+ return
+ }
+ var flag int32
+ if isEof {
+ flag = 1
+ }
+ w.writeBits(flag, 3)
+ w.flush()
+ w.writeBits(int32(length), 16)
+ w.writeBits(int32(^uint16(length)), 16)
+}
+
+func (w *huffmanBitWriter) writeFixedHeader(isEof bool) {
+ if w.err != nil {
+ return
+ }
+ // Indicate that we are a fixed Huffman block
+ var value int32 = 2
+ if isEof {
+ value = 3
+ }
+ w.writeBits(value, 3)
+}
+
+// writeBlock will write a block of tokens with the smallest encoding.
+// The original input can be supplied, and if the huffman encoded data
+// is larger than the original bytes, the data will be written as a
+// stored block.
+// If the input is nil, the tokens will always be Huffman encoded.
+func (w *huffmanBitWriter) writeBlock(tokens []token, eof bool, input []byte) {
+ if w.err != nil {
+ return
+ }
+
+ tokens = append(tokens, endBlockMarker)
+ numLiterals, numOffsets := w.indexTokens(tokens)
+
+ var extraBits int
+ storedSize, storable := w.storedSize(input)
+ if storable {
+ // We only bother calculating the costs of the extra bits required by
+ // the length of offset fields (which will be the same for both fixed
+ // and dynamic encoding), if we need to compare those two encodings
+ // against stored encoding.
+ for lengthCode := lengthCodesStart + 8; lengthCode < numLiterals; lengthCode++ {
+ // First eight length codes have extra size = 0.
+ extraBits += int(w.literalFreq[lengthCode]) * int(lengthExtraBits[lengthCode-lengthCodesStart])
+ }
+ for offsetCode := 4; offsetCode < numOffsets; offsetCode++ {
+ // First four offset codes have extra size = 0.
+ extraBits += int(w.offsetFreq[offsetCode]) * int(offsetExtraBits[offsetCode])
+ }
+ }
+
+ // Figure out smallest code.
+ // Fixed Huffman baseline.
+ var literalEncoding = fixedLiteralEncoding
+ var offsetEncoding = fixedOffsetEncoding
+ var size = w.fixedSize(extraBits)
+
+ // Dynamic Huffman?
+ var numCodegens int
+
+ // Generate codegen and codegenFrequencies, which indicates how to encode
+ // the literalEncoding and the offsetEncoding.
+ w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
+ w.codegenEncoding.generate(w.codegenFreq[:], 7)
+ dynamicSize, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, extraBits)
+
+ if dynamicSize < size {
+ size = dynamicSize
+ literalEncoding = w.literalEncoding
+ offsetEncoding = w.offsetEncoding
+ }
+
+ // Stored bytes?
+ if storable && storedSize < size {
+ w.writeStoredHeader(len(input), eof)
+ w.writeBytes(input)
+ return
+ }
+
+ // Huffman.
+ if literalEncoding == fixedLiteralEncoding {
+ w.writeFixedHeader(eof)
+ } else {
+ w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+ }
+
+ // Write the tokens.
+ w.writeTokens(tokens, literalEncoding.codes, offsetEncoding.codes)
+}
+
+// writeBlockDynamic encodes a block using a dynamic Huffman table.
+// This should be used if the symbols used have a disproportionate
+// histogram distribution.
+// If input is supplied and the compression savings are below 1/16th of the
+// input size the block is stored.
+func (w *huffmanBitWriter) writeBlockDynamic(tokens []token, eof bool, input []byte) {
+ if w.err != nil {
+ return
+ }
+
+ tokens = append(tokens, endBlockMarker)
+ numLiterals, numOffsets := w.indexTokens(tokens)
+
+ // Generate codegen and codegenFrequencies, which indicates how to encode
+ // the literalEncoding and the offsetEncoding.
+ w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
+ w.codegenEncoding.generate(w.codegenFreq[:], 7)
+ size, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, 0)
+
+ // Store bytes, if we don't get a reasonable improvement.
+ if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
+ w.writeStoredHeader(len(input), eof)
+ w.writeBytes(input)
+ return
+ }
+
+ // Write Huffman table.
+ w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+
+ // Write the tokens.
+ w.writeTokens(tokens, w.literalEncoding.codes, w.offsetEncoding.codes)
+}
+
+// indexTokens indexes a slice of tokens, and updates
+// literalFreq and offsetFreq, and generates literalEncoding
+// and offsetEncoding.
+// The number of literal and offset tokens is returned.
+func (w *huffmanBitWriter) indexTokens(tokens []token) (numLiterals, numOffsets int) {
+ for i := range w.literalFreq {
+ w.literalFreq[i] = 0
+ }
+ for i := range w.offsetFreq {
+ w.offsetFreq[i] = 0
+ }
+
+ for _, t := range tokens {
+ if t < matchType {
+ w.literalFreq[t.literal()]++
+ continue
+ }
+ length := t.length()
+ offset := t.offset()
+ w.literalFreq[lengthCodesStart+lengthCode(length)]++
+ w.offsetFreq[offsetCode(offset)]++
+ }
+
+ // get the number of literals
+ numLiterals = len(w.literalFreq)
+ for w.literalFreq[numLiterals-1] == 0 {
+ numLiterals--
+ }
+ // get the number of offsets
+ numOffsets = len(w.offsetFreq)
+ for numOffsets > 0 && w.offsetFreq[numOffsets-1] == 0 {
+ numOffsets--
+ }
+ if numOffsets == 0 {
+ // We haven't found a single match. If we want to go with the dynamic encoding,
+ // we should count at least one offset to be sure that the offset huffman tree could be encoded.
+ w.offsetFreq[0] = 1
+ numOffsets = 1
+ }
+ w.literalEncoding.generate(w.literalFreq, 15)
+ w.offsetEncoding.generate(w.offsetFreq, 15)
+ return
+}
+
+// writeTokens writes a slice of tokens to the output.
+// codes for literal and offset encoding must be supplied.
+func (w *huffmanBitWriter) writeTokens(tokens []token, leCodes, oeCodes []hcode) {
+ if w.err != nil {
+ return
+ }
+ for _, t := range tokens {
+ if t < matchType {
+ w.writeCode(leCodes[t.literal()])
+ continue
+ }
+ // Write the length
+ length := t.length()
+ lengthCode := lengthCode(length)
+ w.writeCode(leCodes[lengthCode+lengthCodesStart])
+ extraLengthBits := uint(lengthExtraBits[lengthCode])
+ if extraLengthBits > 0 {
+ extraLength := int32(length - lengthBase[lengthCode])
+ w.writeBits(extraLength, extraLengthBits)
+ }
+ // Write the offset
+ offset := t.offset()
+ offsetCode := offsetCode(offset)
+ w.writeCode(oeCodes[offsetCode])
+ extraOffsetBits := uint(offsetExtraBits[offsetCode])
+ if extraOffsetBits > 0 {
+ extraOffset := int32(offset - offsetBase[offsetCode])
+ w.writeBits(extraOffset, extraOffsetBits)
+ }
+ }
+}
+
+// huffOffset is a static offset encoder used for huffman only encoding.
+// It can be reused since we will not be encoding offset values.
+var huffOffset *huffmanEncoder
+
+func init() {
+ w := newHuffmanBitWriter(nil)
+ w.offsetFreq[0] = 1
+ huffOffset = newHuffmanEncoder(offsetCodeCount)
+ huffOffset.generate(w.offsetFreq, 15)
+}
+
+// writeBlockHuff encodes a block of bytes as either
+// Huffman encoded literals or uncompressed bytes if the
+// results only gains very little from compression.
+func (w *huffmanBitWriter) writeBlockHuff(eof bool, input []byte) {
+ if w.err != nil {
+ return
+ }
+
+ // Clear histogram
+ for i := range w.literalFreq {
+ w.literalFreq[i] = 0
+ }
+
+ // Add everything as literals
+ histogram(input, w.literalFreq)
+
+ w.literalFreq[endBlockMarker] = 1
+
+ const numLiterals = endBlockMarker + 1
+ const numOffsets = 1
+
+ w.literalEncoding.generate(w.literalFreq, 15)
+
+ // Figure out smallest code.
+ // Always use dynamic Huffman or Store
+ var numCodegens int
+
+ // Generate codegen and codegenFrequencies, which indicates how to encode
+ // the literalEncoding and the offsetEncoding.
+ w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, huffOffset)
+ w.codegenEncoding.generate(w.codegenFreq[:], 7)
+ size, numCodegens := w.dynamicSize(w.literalEncoding, huffOffset, 0)
+
+ // Store bytes, if we don't get a reasonable improvement.
+ if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
+ w.writeStoredHeader(len(input), eof)
+ w.writeBytes(input)
+ return
+ }
+
+ // Huffman.
+ w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+ encoding := w.literalEncoding.codes[:257]
+ n := w.nbytes
+ for _, t := range input {
+ // Bitwriting inlined, ~30% speedup
+ c := encoding[t]
+ w.bits |= uint64(c.code) << w.nbits
+ w.nbits += uint(c.len)
+ if w.nbits < 48 {
+ continue
+ }
+ // Store 6 bytes
+ bits := w.bits
+ w.bits >>= 48
+ w.nbits -= 48
+ bytes := w.bytes[n : n+6]
+ bytes[0] = byte(bits)
+ bytes[1] = byte(bits >> 8)
+ bytes[2] = byte(bits >> 16)
+ bytes[3] = byte(bits >> 24)
+ bytes[4] = byte(bits >> 32)
+ bytes[5] = byte(bits >> 40)
+ n += 6
+ if n < bufferFlushSize {
+ continue
+ }
+ w.write(w.bytes[:n])
+ if w.err != nil {
+ return // Return early in the event of write failures
+ }
+ n = 0
+ }
+ w.nbytes = n
+ w.writeCode(encoding[endBlockMarker])
+}
diff --git a/vendor/github.com/klauspost/compress/flate/huffman_code.go b/vendor/github.com/klauspost/compress/flate/huffman_code.go
new file mode 100644
index 000000000..bdcbd823b
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/huffman_code.go
@@ -0,0 +1,344 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+ "math"
+ "sort"
+)
+
+// hcode is a huffman code with a bit code and bit length.
+type hcode struct {
+ code, len uint16
+}
+
+type huffmanEncoder struct {
+ codes []hcode
+ freqcache []literalNode
+ bitCount [17]int32
+ lns byLiteral // stored to avoid repeated allocation in generate
+ lfs byFreq // stored to avoid repeated allocation in generate
+}
+
+type literalNode struct {
+ literal uint16
+ freq int32
+}
+
+// A levelInfo describes the state of the constructed tree for a given depth.
+type levelInfo struct {
+ // Our level. for better printing
+ level int32
+
+ // The frequency of the last node at this level
+ lastFreq int32
+
+ // The frequency of the next character to add to this level
+ nextCharFreq int32
+
+ // The frequency of the next pair (from level below) to add to this level.
+ // Only valid if the "needed" value of the next lower level is 0.
+ nextPairFreq int32
+
+ // The number of chains remaining to generate for this level before moving
+ // up to the next level
+ needed int32
+}
+
+// set sets the code and length of an hcode.
+func (h *hcode) set(code uint16, length uint16) {
+ h.len = length
+ h.code = code
+}
+
+func maxNode() literalNode { return literalNode{math.MaxUint16, math.MaxInt32} }
+
+func newHuffmanEncoder(size int) *huffmanEncoder {
+ return &huffmanEncoder{codes: make([]hcode, size)}
+}
+
+// Generates a HuffmanCode corresponding to the fixed literal table
+func generateFixedLiteralEncoding() *huffmanEncoder {
+ h := newHuffmanEncoder(maxNumLit)
+ codes := h.codes
+ var ch uint16
+ for ch = 0; ch < maxNumLit; ch++ {
+ var bits uint16
+ var size uint16
+ switch {
+ case ch < 144:
+ // size 8, 000110000 .. 10111111
+ bits = ch + 48
+ size = 8
+ break
+ case ch < 256:
+ // size 9, 110010000 .. 111111111
+ bits = ch + 400 - 144
+ size = 9
+ break
+ case ch < 280:
+ // size 7, 0000000 .. 0010111
+ bits = ch - 256
+ size = 7
+ break
+ default:
+ // size 8, 11000000 .. 11000111
+ bits = ch + 192 - 280
+ size = 8
+ }
+ codes[ch] = hcode{code: reverseBits(bits, byte(size)), len: size}
+ }
+ return h
+}
+
+func generateFixedOffsetEncoding() *huffmanEncoder {
+ h := newHuffmanEncoder(30)
+ codes := h.codes
+ for ch := range codes {
+ codes[ch] = hcode{code: reverseBits(uint16(ch), 5), len: 5}
+ }
+ return h
+}
+
+var fixedLiteralEncoding *huffmanEncoder = generateFixedLiteralEncoding()
+var fixedOffsetEncoding *huffmanEncoder = generateFixedOffsetEncoding()
+
+func (h *huffmanEncoder) bitLength(freq []int32) int {
+ var total int
+ for i, f := range freq {
+ if f != 0 {
+ total += int(f) * int(h.codes[i].len)
+ }
+ }
+ return total
+}
+
+const maxBitsLimit = 16
+
+// Return the number of literals assigned to each bit size in the Huffman encoding
+//
+// This method is only called when list.length >= 3
+// The cases of 0, 1, and 2 literals are handled by special case code.
+//
+// list An array of the literals with non-zero frequencies
+// and their associated frequencies. The array is in order of increasing
+// frequency, and has as its last element a special element with frequency
+// MaxInt32
+// maxBits The maximum number of bits that should be used to encode any literal.
+// Must be less than 16.
+// return An integer array in which array[i] indicates the number of literals
+// that should be encoded in i bits.
+func (h *huffmanEncoder) bitCounts(list []literalNode, maxBits int32) []int32 {
+ if maxBits >= maxBitsLimit {
+ panic("flate: maxBits too large")
+ }
+ n := int32(len(list))
+ list = list[0 : n+1]
+ list[n] = maxNode()
+
+ // The tree can't have greater depth than n - 1, no matter what. This
+ // saves a little bit of work in some small cases
+ if maxBits > n-1 {
+ maxBits = n - 1
+ }
+
+ // Create information about each of the levels.
+ // A bogus "Level 0" whose sole purpose is so that
+ // level1.prev.needed==0. This makes level1.nextPairFreq
+ // be a legitimate value that never gets chosen.
+ var levels [maxBitsLimit]levelInfo
+ // leafCounts[i] counts the number of literals at the left
+ // of ancestors of the rightmost node at level i.
+ // leafCounts[i][j] is the number of literals at the left
+ // of the level j ancestor.
+ var leafCounts [maxBitsLimit][maxBitsLimit]int32
+
+ for level := int32(1); level <= maxBits; level++ {
+ // For every level, the first two items are the first two characters.
+ // We initialize the levels as if we had already figured this out.
+ levels[level] = levelInfo{
+ level: level,
+ lastFreq: list[1].freq,
+ nextCharFreq: list[2].freq,
+ nextPairFreq: list[0].freq + list[1].freq,
+ }
+ leafCounts[level][level] = 2
+ if level == 1 {
+ levels[level].nextPairFreq = math.MaxInt32
+ }
+ }
+
+ // We need a total of 2*n - 2 items at top level and have already generated 2.
+ levels[maxBits].needed = 2*n - 4
+
+ level := maxBits
+ for {
+ l := &levels[level]
+ if l.nextPairFreq == math.MaxInt32 && l.nextCharFreq == math.MaxInt32 {
+ // We've run out of both leafs and pairs.
+ // End all calculations for this level.
+ // To make sure we never come back to this level or any lower level,
+ // set nextPairFreq impossibly large.
+ l.needed = 0
+ levels[level+1].nextPairFreq = math.MaxInt32
+ level++
+ continue
+ }
+
+ prevFreq := l.lastFreq
+ if l.nextCharFreq < l.nextPairFreq {
+ // The next item on this row is a leaf node.
+ n := leafCounts[level][level] + 1
+ l.lastFreq = l.nextCharFreq
+ // Lower leafCounts are the same of the previous node.
+ leafCounts[level][level] = n
+ l.nextCharFreq = list[n].freq
+ } else {
+ // The next item on this row is a pair from the previous row.
+ // nextPairFreq isn't valid until we generate two
+ // more values in the level below
+ l.lastFreq = l.nextPairFreq
+ // Take leaf counts from the lower level, except counts[level] remains the same.
+ copy(leafCounts[level][:level], leafCounts[level-1][:level])
+ levels[l.level-1].needed = 2
+ }
+
+ if l.needed--; l.needed == 0 {
+ // We've done everything we need to do for this level.
+ // Continue calculating one level up. Fill in nextPairFreq
+ // of that level with the sum of the two nodes we've just calculated on
+ // this level.
+ if l.level == maxBits {
+ // All done!
+ break
+ }
+ levels[l.level+1].nextPairFreq = prevFreq + l.lastFreq
+ level++
+ } else {
+ // If we stole from below, move down temporarily to replenish it.
+ for levels[level-1].needed > 0 {
+ level--
+ }
+ }
+ }
+
+ // Somethings is wrong if at the end, the top level is null or hasn't used
+ // all of the leaves.
+ if leafCounts[maxBits][maxBits] != n {
+ panic("leafCounts[maxBits][maxBits] != n")
+ }
+
+ bitCount := h.bitCount[:maxBits+1]
+ bits := 1
+ counts := &leafCounts[maxBits]
+ for level := maxBits; level > 0; level-- {
+ // chain.leafCount gives the number of literals requiring at least "bits"
+ // bits to encode.
+ bitCount[bits] = counts[level] - counts[level-1]
+ bits++
+ }
+ return bitCount
+}
+
+// Look at the leaves and assign them a bit count and an encoding as specified
+// in RFC 1951 3.2.2
+func (h *huffmanEncoder) assignEncodingAndSize(bitCount []int32, list []literalNode) {
+ code := uint16(0)
+ for n, bits := range bitCount {
+ code <<= 1
+ if n == 0 || bits == 0 {
+ continue
+ }
+ // The literals list[len(list)-bits] .. list[len(list)-bits]
+ // are encoded using "bits" bits, and get the values
+ // code, code + 1, .... The code values are
+ // assigned in literal order (not frequency order).
+ chunk := list[len(list)-int(bits):]
+
+ h.lns.sort(chunk)
+ for _, node := range chunk {
+ h.codes[node.literal] = hcode{code: reverseBits(code, uint8(n)), len: uint16(n)}
+ code++
+ }
+ list = list[0 : len(list)-int(bits)]
+ }
+}
+
+// Update this Huffman Code object to be the minimum code for the specified frequency count.
+//
+// freq An array of frequencies, in which frequency[i] gives the frequency of literal i.
+// maxBits The maximum number of bits to use for any literal.
+func (h *huffmanEncoder) generate(freq []int32, maxBits int32) {
+ if h.freqcache == nil {
+ // Allocate a reusable buffer with the longest possible frequency table.
+ // Possible lengths are codegenCodeCount, offsetCodeCount and maxNumLit.
+ // The largest of these is maxNumLit, so we allocate for that case.
+ h.freqcache = make([]literalNode, maxNumLit+1)
+ }
+ list := h.freqcache[:len(freq)+1]
+ // Number of non-zero literals
+ count := 0
+ // Set list to be the set of all non-zero literals and their frequencies
+ for i, f := range freq {
+ if f != 0 {
+ list[count] = literalNode{uint16(i), f}
+ count++
+ } else {
+ list[count] = literalNode{}
+ h.codes[i].len = 0
+ }
+ }
+ list[len(freq)] = literalNode{}
+
+ list = list[:count]
+ if count <= 2 {
+ // Handle the small cases here, because they are awkward for the general case code. With
+ // two or fewer literals, everything has bit length 1.
+ for i, node := range list {
+ // "list" is in order of increasing literal value.
+ h.codes[node.literal].set(uint16(i), 1)
+ }
+ return
+ }
+ h.lfs.sort(list)
+
+ // Get the number of literals for each bit count
+ bitCount := h.bitCounts(list, maxBits)
+ // And do the assignment
+ h.assignEncodingAndSize(bitCount, list)
+}
+
+type byLiteral []literalNode
+
+func (s *byLiteral) sort(a []literalNode) {
+ *s = byLiteral(a)
+ sort.Sort(s)
+}
+
+func (s byLiteral) Len() int { return len(s) }
+
+func (s byLiteral) Less(i, j int) bool {
+ return s[i].literal < s[j].literal
+}
+
+func (s byLiteral) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+type byFreq []literalNode
+
+func (s *byFreq) sort(a []literalNode) {
+ *s = byFreq(a)
+ sort.Sort(s)
+}
+
+func (s byFreq) Len() int { return len(s) }
+
+func (s byFreq) Less(i, j int) bool {
+ if s[i].freq == s[j].freq {
+ return s[i].literal < s[j].literal
+ }
+ return s[i].freq < s[j].freq
+}
+
+func (s byFreq) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
diff --git a/vendor/github.com/klauspost/compress/flate/inflate.go b/vendor/github.com/klauspost/compress/flate/inflate.go
new file mode 100644
index 000000000..800d0ce9e
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/inflate.go
@@ -0,0 +1,880 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package flate implements the DEFLATE compressed data format, described in
+// RFC 1951. The gzip and zlib packages implement access to DEFLATE-based file
+// formats.
+package flate
+
+import (
+ "bufio"
+ "io"
+ "math/bits"
+ "strconv"
+ "sync"
+)
+
+const (
+ maxCodeLen = 16 // max length of Huffman code
+ maxCodeLenMask = 15 // mask for max length of Huffman code
+ // The next three numbers come from the RFC section 3.2.7, with the
+ // additional proviso in section 3.2.5 which implies that distance codes
+ // 30 and 31 should never occur in compressed data.
+ maxNumLit = 286
+ maxNumDist = 30
+ numCodes = 19 // number of codes in Huffman meta-code
+)
+
+// Initialize the fixedHuffmanDecoder only once upon first use.
+var fixedOnce sync.Once
+var fixedHuffmanDecoder huffmanDecoder
+
+// A CorruptInputError reports the presence of corrupt input at a given offset.
+type CorruptInputError int64
+
+func (e CorruptInputError) Error() string {
+ return "flate: corrupt input before offset " + strconv.FormatInt(int64(e), 10)
+}
+
+// An InternalError reports an error in the flate code itself.
+type InternalError string
+
+func (e InternalError) Error() string { return "flate: internal error: " + string(e) }
+
+// A ReadError reports an error encountered while reading input.
+//
+// Deprecated: No longer returned.
+type ReadError struct {
+ Offset int64 // byte offset where error occurred
+ Err error // error returned by underlying Read
+}
+
+func (e *ReadError) Error() string {
+ return "flate: read error at offset " + strconv.FormatInt(e.Offset, 10) + ": " + e.Err.Error()
+}
+
+// A WriteError reports an error encountered while writing output.
+//
+// Deprecated: No longer returned.
+type WriteError struct {
+ Offset int64 // byte offset where error occurred
+ Err error // error returned by underlying Write
+}
+
+func (e *WriteError) Error() string {
+ return "flate: write error at offset " + strconv.FormatInt(e.Offset, 10) + ": " + e.Err.Error()
+}
+
+// Resetter resets a ReadCloser returned by NewReader or NewReaderDict to
+// to switch to a new underlying Reader. This permits reusing a ReadCloser
+// instead of allocating a new one.
+type Resetter interface {
+ // Reset discards any buffered data and resets the Resetter as if it was
+ // newly initialized with the given reader.
+ Reset(r io.Reader, dict []byte) error
+}
+
+// The data structure for decoding Huffman tables is based on that of
+// zlib. There is a lookup table of a fixed bit width (huffmanChunkBits),
+// For codes smaller than the table width, there are multiple entries
+// (each combination of trailing bits has the same value). For codes
+// larger than the table width, the table contains a link to an overflow
+// table. The width of each entry in the link table is the maximum code
+// size minus the chunk width.
+//
+// Note that you can do a lookup in the table even without all bits
+// filled. Since the extra bits are zero, and the DEFLATE Huffman codes
+// have the property that shorter codes come before longer ones, the
+// bit length estimate in the result is a lower bound on the actual
+// number of bits.
+//
+// See the following:
+// http://www.gzip.org/algorithm.txt
+
+// chunk & 15 is number of bits
+// chunk >> 4 is value, including table link
+
+const (
+ huffmanChunkBits = 9
+ huffmanNumChunks = 1 << huffmanChunkBits
+ huffmanCountMask = 15
+ huffmanValueShift = 4
+)
+
+type huffmanDecoder struct {
+ min int // the minimum code length
+ chunks *[huffmanNumChunks]uint32 // chunks as described above
+ links [][]uint32 // overflow links
+ linkMask uint32 // mask the width of the link table
+}
+
+// Initialize Huffman decoding tables from array of code lengths.
+// Following this function, h is guaranteed to be initialized into a complete
+// tree (i.e., neither over-subscribed nor under-subscribed). The exception is a
+// degenerate case where the tree has only a single symbol with length 1. Empty
+// trees are permitted.
+func (h *huffmanDecoder) init(lengths []int) bool {
+ // Sanity enables additional runtime tests during Huffman
+ // table construction. It's intended to be used during
+ // development to supplement the currently ad-hoc unit tests.
+ const sanity = false
+
+ if h.chunks == nil {
+ h.chunks = &[huffmanNumChunks]uint32{}
+ }
+ if h.min != 0 {
+ *h = huffmanDecoder{chunks: h.chunks, links: h.links}
+ }
+
+ // Count number of codes of each length,
+ // compute min and max length.
+ var count [maxCodeLen]int
+ var min, max int
+ for _, n := range lengths {
+ if n == 0 {
+ continue
+ }
+ if min == 0 || n < min {
+ min = n
+ }
+ if n > max {
+ max = n
+ }
+ count[n&maxCodeLenMask]++
+ }
+
+ // Empty tree. The decompressor.huffSym function will fail later if the tree
+ // is used. Technically, an empty tree is only valid for the HDIST tree and
+ // not the HCLEN and HLIT tree. However, a stream with an empty HCLEN tree
+ // is guaranteed to fail since it will attempt to use the tree to decode the
+ // codes for the HLIT and HDIST trees. Similarly, an empty HLIT tree is
+ // guaranteed to fail later since the compressed data section must be
+ // composed of at least one symbol (the end-of-block marker).
+ if max == 0 {
+ return true
+ }
+
+ code := 0
+ var nextcode [maxCodeLen]int
+ for i := min; i <= max; i++ {
+ code <<= 1
+ nextcode[i&maxCodeLenMask] = code
+ code += count[i&maxCodeLenMask]
+ }
+
+ // Check that the coding is complete (i.e., that we've
+ // assigned all 2-to-the-max possible bit sequences).
+ // Exception: To be compatible with zlib, we also need to
+ // accept degenerate single-code codings. See also
+ // TestDegenerateHuffmanCoding.
+ if code != 1<<uint(max) && !(code == 1 && max == 1) {
+ return false
+ }
+
+ h.min = min
+ chunks := h.chunks[:]
+ for i := range chunks {
+ chunks[i] = 0
+ }
+
+ if max > huffmanChunkBits {
+ numLinks := 1 << (uint(max) - huffmanChunkBits)
+ h.linkMask = uint32(numLinks - 1)
+
+ // create link tables
+ link := nextcode[huffmanChunkBits+1] >> 1
+ if cap(h.links) < huffmanNumChunks-link {
+ h.links = make([][]uint32, huffmanNumChunks-link)
+ } else {
+ h.links = h.links[:huffmanNumChunks-link]
+ }
+ for j := uint(link); j < huffmanNumChunks; j++ {
+ reverse := int(bits.Reverse16(uint16(j)))
+ reverse >>= uint(16 - huffmanChunkBits)
+ off := j - uint(link)
+ if sanity && h.chunks[reverse] != 0 {
+ panic("impossible: overwriting existing chunk")
+ }
+ h.chunks[reverse] = uint32(off<<huffmanValueShift | (huffmanChunkBits + 1))
+ if cap(h.links[off]) < numLinks {
+ h.links[off] = make([]uint32, numLinks)
+ } else {
+ links := h.links[off][:0]
+ h.links[off] = links[:numLinks]
+ }
+ }
+ } else {
+ h.links = h.links[:0]
+ }
+
+ for i, n := range lengths {
+ if n == 0 {
+ continue
+ }
+ code := nextcode[n]
+ nextcode[n]++
+ chunk := uint32(i<<huffmanValueShift | n)
+ reverse := int(bits.Reverse16(uint16(code)))
+ reverse >>= uint(16 - n)
+ if n <= huffmanChunkBits {
+ for off := reverse; off < len(h.chunks); off += 1 << uint(n) {
+ // We should never need to overwrite
+ // an existing chunk. Also, 0 is
+ // never a valid chunk, because the
+ // lower 4 "count" bits should be
+ // between 1 and 15.
+ if sanity && h.chunks[off] != 0 {
+ panic("impossible: overwriting existing chunk")
+ }
+ h.chunks[off] = chunk
+ }
+ } else {
+ j := reverse & (huffmanNumChunks - 1)
+ if sanity && h.chunks[j]&huffmanCountMask != huffmanChunkBits+1 {
+ // Longer codes should have been
+ // associated with a link table above.
+ panic("impossible: not an indirect chunk")
+ }
+ value := h.chunks[j] >> huffmanValueShift
+ linktab := h.links[value]
+ reverse >>= huffmanChunkBits
+ for off := reverse; off < len(linktab); off += 1 << uint(n-huffmanChunkBits) {
+ if sanity && linktab[off] != 0 {
+ panic("impossible: overwriting existing chunk")
+ }
+ linktab[off] = chunk
+ }
+ }
+ }
+
+ if sanity {
+ // Above we've sanity checked that we never overwrote
+ // an existing entry. Here we additionally check that
+ // we filled the tables completely.
+ for i, chunk := range h.chunks {
+ if chunk == 0 {
+ // As an exception, in the degenerate
+ // single-code case, we allow odd
+ // chunks to be missing.
+ if code == 1 && i%2 == 1 {
+ continue
+ }
+ panic("impossible: missing chunk")
+ }
+ }
+ for _, linktab := range h.links {
+ for _, chunk := range linktab {
+ if chunk == 0 {
+ panic("impossible: missing chunk")
+ }
+ }
+ }
+ }
+
+ return true
+}
+
+// The actual read interface needed by NewReader.
+// If the passed in io.Reader does not also have ReadByte,
+// the NewReader will introduce its own buffering.
+type Reader interface {
+ io.Reader
+ io.ByteReader
+}
+
+// Decompress state.
+type decompressor struct {
+ // Input source.
+ r Reader
+ roffset int64
+
+ // Input bits, in top of b.
+ b uint32
+ nb uint
+
+ // Huffman decoders for literal/length, distance.
+ h1, h2 huffmanDecoder
+
+ // Length arrays used to define Huffman codes.
+ bits *[maxNumLit + maxNumDist]int
+ codebits *[numCodes]int
+
+ // Output history, buffer.
+ dict dictDecoder
+
+ // Temporary buffer (avoids repeated allocation).
+ buf [4]byte
+
+ // Next step in the decompression,
+ // and decompression state.
+ step func(*decompressor)
+ stepState int
+ final bool
+ err error
+ toRead []byte
+ hl, hd *huffmanDecoder
+ copyLen int
+ copyDist int
+}
+
+func (f *decompressor) nextBlock() {
+ for f.nb < 1+2 {
+ if f.err = f.moreBits(); f.err != nil {
+ return
+ }
+ }
+ f.final = f.b&1 == 1
+ f.b >>= 1
+ typ := f.b & 3
+ f.b >>= 2
+ f.nb -= 1 + 2
+ switch typ {
+ case 0:
+ f.dataBlock()
+ case 1:
+ // compressed, fixed Huffman tables
+ f.hl = &fixedHuffmanDecoder
+ f.hd = nil
+ f.huffmanBlock()
+ case 2:
+ // compressed, dynamic Huffman tables
+ if f.err = f.readHuffman(); f.err != nil {
+ break
+ }
+ f.hl = &f.h1
+ f.hd = &f.h2
+ f.huffmanBlock()
+ default:
+ // 3 is reserved.
+ f.err = CorruptInputError(f.roffset)
+ }
+}
+
+func (f *decompressor) Read(b []byte) (int, error) {
+ for {
+ if len(f.toRead) > 0 {
+ n := copy(b, f.toRead)
+ f.toRead = f.toRead[n:]
+ if len(f.toRead) == 0 {
+ return n, f.err
+ }
+ return n, nil
+ }
+ if f.err != nil {
+ return 0, f.err
+ }
+ f.step(f)
+ if f.err != nil && len(f.toRead) == 0 {
+ f.toRead = f.dict.readFlush() // Flush what's left in case of error
+ }
+ }
+}
+
+// Support the io.WriteTo interface for io.Copy and friends.
+func (f *decompressor) WriteTo(w io.Writer) (int64, error) {
+ total := int64(0)
+ flushed := false
+ for {
+ if len(f.toRead) > 0 {
+ n, err := w.Write(f.toRead)
+ total += int64(n)
+ if err != nil {
+ f.err = err
+ return total, err
+ }
+ if n != len(f.toRead) {
+ return total, io.ErrShortWrite
+ }
+ f.toRead = f.toRead[:0]
+ }
+ if f.err != nil && flushed {
+ if f.err == io.EOF {
+ return total, nil
+ }
+ return total, f.err
+ }
+ if f.err == nil {
+ f.step(f)
+ }
+ if len(f.toRead) == 0 && f.err != nil && !flushed {
+ f.toRead = f.dict.readFlush() // Flush what's left in case of error
+ flushed = true
+ }
+ }
+}
+
+func (f *decompressor) Close() error {
+ if f.err == io.EOF {
+ return nil
+ }
+ return f.err
+}
+
+// RFC 1951 section 3.2.7.
+// Compression with dynamic Huffman codes
+
+var codeOrder = [...]int{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+func (f *decompressor) readHuffman() error {
+ // HLIT[5], HDIST[5], HCLEN[4].
+ for f.nb < 5+5+4 {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ nlit := int(f.b&0x1F) + 257
+ if nlit > maxNumLit {
+ return CorruptInputError(f.roffset)
+ }
+ f.b >>= 5
+ ndist := int(f.b&0x1F) + 1
+ if ndist > maxNumDist {
+ return CorruptInputError(f.roffset)
+ }
+ f.b >>= 5
+ nclen := int(f.b&0xF) + 4
+ // numCodes is 19, so nclen is always valid.
+ f.b >>= 4
+ f.nb -= 5 + 5 + 4
+
+ // (HCLEN+4)*3 bits: code lengths in the magic codeOrder order.
+ for i := 0; i < nclen; i++ {
+ for f.nb < 3 {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ f.codebits[codeOrder[i]] = int(f.b & 0x7)
+ f.b >>= 3
+ f.nb -= 3
+ }
+ for i := nclen; i < len(codeOrder); i++ {
+ f.codebits[codeOrder[i]] = 0
+ }
+ if !f.h1.init(f.codebits[0:]) {
+ return CorruptInputError(f.roffset)
+ }
+
+ // HLIT + 257 code lengths, HDIST + 1 code lengths,
+ // using the code length Huffman code.
+ for i, n := 0, nlit+ndist; i < n; {
+ x, err := f.huffSym(&f.h1)
+ if err != nil {
+ return err
+ }
+ if x < 16 {
+ // Actual length.
+ f.bits[i] = x
+ i++
+ continue
+ }
+ // Repeat previous length or zero.
+ var rep int
+ var nb uint
+ var b int
+ switch x {
+ default:
+ return InternalError("unexpected length code")
+ case 16:
+ rep = 3
+ nb = 2
+ if i == 0 {
+ return CorruptInputError(f.roffset)
+ }
+ b = f.bits[i-1]
+ case 17:
+ rep = 3
+ nb = 3
+ b = 0
+ case 18:
+ rep = 11
+ nb = 7
+ b = 0
+ }
+ for f.nb < nb {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ rep += int(f.b & uint32(1<<nb-1))
+ f.b >>= nb
+ f.nb -= nb
+ if i+rep > n {
+ return CorruptInputError(f.roffset)
+ }
+ for j := 0; j < rep; j++ {
+ f.bits[i] = b
+ i++
+ }
+ }
+
+ if !f.h1.init(f.bits[0:nlit]) || !f.h2.init(f.bits[nlit:nlit+ndist]) {
+ return CorruptInputError(f.roffset)
+ }
+
+ // As an optimization, we can initialize the min bits to read at a time
+ // for the HLIT tree to the length of the EOB marker since we know that
+ // every block must terminate with one. This preserves the property that
+ // we never read any extra bytes after the end of the DEFLATE stream.
+ if f.h1.min < f.bits[endBlockMarker] {
+ f.h1.min = f.bits[endBlockMarker]
+ }
+
+ return nil
+}
+
+// Decode a single Huffman block from f.
+// hl and hd are the Huffman states for the lit/length values
+// and the distance values, respectively. If hd == nil, using the
+// fixed distance encoding associated with fixed Huffman blocks.
+func (f *decompressor) huffmanBlock() {
+ const (
+ stateInit = iota // Zero value must be stateInit
+ stateDict
+ )
+
+ switch f.stepState {
+ case stateInit:
+ goto readLiteral
+ case stateDict:
+ goto copyHistory
+ }
+
+readLiteral:
+ // Read literal and/or (length, distance) according to RFC section 3.2.3.
+ {
+ v, err := f.huffSym(f.hl)
+ if err != nil {
+ f.err = err
+ return
+ }
+ var n uint // number of bits extra
+ var length int
+ switch {
+ case v < 256:
+ f.dict.writeByte(byte(v))
+ if f.dict.availWrite() == 0 {
+ f.toRead = f.dict.readFlush()
+ f.step = (*decompressor).huffmanBlock
+ f.stepState = stateInit
+ return
+ }
+ goto readLiteral
+ case v == 256:
+ f.finishBlock()
+ return
+ // otherwise, reference to older data
+ case v < 265:
+ length = v - (257 - 3)
+ n = 0
+ case v < 269:
+ length = v*2 - (265*2 - 11)
+ n = 1
+ case v < 273:
+ length = v*4 - (269*4 - 19)
+ n = 2
+ case v < 277:
+ length = v*8 - (273*8 - 35)
+ n = 3
+ case v < 281:
+ length = v*16 - (277*16 - 67)
+ n = 4
+ case v < 285:
+ length = v*32 - (281*32 - 131)
+ n = 5
+ case v < maxNumLit:
+ length = 258
+ n = 0
+ default:
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+ if n > 0 {
+ for f.nb < n {
+ if err = f.moreBits(); err != nil {
+ f.err = err
+ return
+ }
+ }
+ length += int(f.b & uint32(1<<n-1))
+ f.b >>= n
+ f.nb -= n
+ }
+
+ var dist int
+ if f.hd == nil {
+ for f.nb < 5 {
+ if err = f.moreBits(); err != nil {
+ f.err = err
+ return
+ }
+ }
+ dist = int(bits.Reverse8(uint8(f.b & 0x1F << 3)))
+ f.b >>= 5
+ f.nb -= 5
+ } else {
+ if dist, err = f.huffSym(f.hd); err != nil {
+ f.err = err
+ return
+ }
+ }
+
+ switch {
+ case dist < 4:
+ dist++
+ case dist < maxNumDist:
+ nb := uint(dist-2) >> 1
+ // have 1 bit in bottom of dist, need nb more.
+ extra := (dist & 1) << nb
+ for f.nb < nb {
+ if err = f.moreBits(); err != nil {
+ f.err = err
+ return
+ }
+ }
+ extra |= int(f.b & uint32(1<<nb-1))
+ f.b >>= nb
+ f.nb -= nb
+ dist = 1<<(nb+1) + 1 + extra
+ default:
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+
+ // No check on length; encoding can be prescient.
+ if dist > f.dict.histSize() {
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+
+ f.copyLen, f.copyDist = length, dist
+ goto copyHistory
+ }
+
+copyHistory:
+ // Perform a backwards copy according to RFC section 3.2.3.
+ {
+ cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
+ if cnt == 0 {
+ cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
+ }
+ f.copyLen -= cnt
+
+ if f.dict.availWrite() == 0 || f.copyLen > 0 {
+ f.toRead = f.dict.readFlush()
+ f.step = (*decompressor).huffmanBlock // We need to continue this work
+ f.stepState = stateDict
+ return
+ }
+ goto readLiteral
+ }
+}
+
+// Copy a single uncompressed data block from input to output.
+func (f *decompressor) dataBlock() {
+ // Uncompressed.
+ // Discard current half-byte.
+ f.nb = 0
+ f.b = 0
+
+ // Length then ones-complement of length.
+ nr, err := io.ReadFull(f.r, f.buf[0:4])
+ f.roffset += int64(nr)
+ if err != nil {
+ f.err = noEOF(err)
+ return
+ }
+ n := int(f.buf[0]) | int(f.buf[1])<<8
+ nn := int(f.buf[2]) | int(f.buf[3])<<8
+ if uint16(nn) != uint16(^n) {
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+
+ if n == 0 {
+ f.toRead = f.dict.readFlush()
+ f.finishBlock()
+ return
+ }
+
+ f.copyLen = n
+ f.copyData()
+}
+
+// copyData copies f.copyLen bytes from the underlying reader into f.hist.
+// It pauses for reads when f.hist is full.
+func (f *decompressor) copyData() {
+ buf := f.dict.writeSlice()
+ if len(buf) > f.copyLen {
+ buf = buf[:f.copyLen]
+ }
+
+ cnt, err := io.ReadFull(f.r, buf)
+ f.roffset += int64(cnt)
+ f.copyLen -= cnt
+ f.dict.writeMark(cnt)
+ if err != nil {
+ f.err = noEOF(err)
+ return
+ }
+
+ if f.dict.availWrite() == 0 || f.copyLen > 0 {
+ f.toRead = f.dict.readFlush()
+ f.step = (*decompressor).copyData
+ return
+ }
+ f.finishBlock()
+}
+
+func (f *decompressor) finishBlock() {
+ if f.final {
+ if f.dict.availRead() > 0 {
+ f.toRead = f.dict.readFlush()
+ }
+ f.err = io.EOF
+ }
+ f.step = (*decompressor).nextBlock
+}
+
+// noEOF returns err, unless err == io.EOF, in which case it returns io.ErrUnexpectedEOF.
+func noEOF(e error) error {
+ if e == io.EOF {
+ return io.ErrUnexpectedEOF
+ }
+ return e
+}
+
+func (f *decompressor) moreBits() error {
+ c, err := f.r.ReadByte()
+ if err != nil {
+ return noEOF(err)
+ }
+ f.roffset++
+ f.b |= uint32(c) << f.nb
+ f.nb += 8
+ return nil
+}
+
+// Read the next Huffman-encoded symbol from f according to h.
+func (f *decompressor) huffSym(h *huffmanDecoder) (int, error) {
+ // Since a huffmanDecoder can be empty or be composed of a degenerate tree
+ // with single element, huffSym must error on these two edge cases. In both
+ // cases, the chunks slice will be 0 for the invalid sequence, leading it
+ // satisfy the n == 0 check below.
+ n := uint(h.min)
+ // Optimization. Compiler isn't smart enough to keep f.b,f.nb in registers,
+ // but is smart enough to keep local variables in registers, so use nb and b,
+ // inline call to moreBits and reassign b,nb back to f on return.
+ nb, b := f.nb, f.b
+ for {
+ for nb < n {
+ c, err := f.r.ReadByte()
+ if err != nil {
+ f.b = b
+ f.nb = nb
+ return 0, noEOF(err)
+ }
+ f.roffset++
+ b |= uint32(c) << (nb & 31)
+ nb += 8
+ }
+ chunk := h.chunks[b&(huffmanNumChunks-1)]
+ n = uint(chunk & huffmanCountMask)
+ if n > huffmanChunkBits {
+ chunk = h.links[chunk>>huffmanValueShift][(b>>huffmanChunkBits)&h.linkMask]
+ n = uint(chunk & huffmanCountMask)
+ }
+ if n <= nb {
+ if n == 0 {
+ f.b = b
+ f.nb = nb
+ f.err = CorruptInputError(f.roffset)
+ return 0, f.err
+ }
+ f.b = b >> (n & 31)
+ f.nb = nb - n
+ return int(chunk >> huffmanValueShift), nil
+ }
+ }
+}
+
+func makeReader(r io.Reader) Reader {
+ if rr, ok := r.(Reader); ok {
+ return rr
+ }
+ return bufio.NewReader(r)
+}
+
+func fixedHuffmanDecoderInit() {
+ fixedOnce.Do(func() {
+ // These come from the RFC section 3.2.6.
+ var bits [288]int
+ for i := 0; i < 144; i++ {
+ bits[i] = 8
+ }
+ for i := 144; i < 256; i++ {
+ bits[i] = 9
+ }
+ for i := 256; i < 280; i++ {
+ bits[i] = 7
+ }
+ for i := 280; i < 288; i++ {
+ bits[i] = 8
+ }
+ fixedHuffmanDecoder.init(bits[:])
+ })
+}
+
+func (f *decompressor) Reset(r io.Reader, dict []byte) error {
+ *f = decompressor{
+ r: makeReader(r),
+ bits: f.bits,
+ codebits: f.codebits,
+ h1: f.h1,
+ h2: f.h2,
+ dict: f.dict,
+ step: (*decompressor).nextBlock,
+ }
+ f.dict.init(maxMatchOffset, dict)
+ return nil
+}
+
+// NewReader returns a new ReadCloser that can be used
+// to read the uncompressed version of r.
+// If r does not also implement io.ByteReader,
+// the decompressor may read more data than necessary from r.
+// It is the caller's responsibility to call Close on the ReadCloser
+// when finished reading.
+//
+// The ReadCloser returned by NewReader also implements Resetter.
+func NewReader(r io.Reader) io.ReadCloser {
+ fixedHuffmanDecoderInit()
+
+ var f decompressor
+ f.r = makeReader(r)
+ f.bits = new([maxNumLit + maxNumDist]int)
+ f.codebits = new([numCodes]int)
+ f.step = (*decompressor).nextBlock
+ f.dict.init(maxMatchOffset, nil)
+ return &f
+}
+
+// NewReaderDict is like NewReader but initializes the reader
+// with a preset dictionary. The returned Reader behaves as if
+// the uncompressed data stream started with the given dictionary,
+// which has already been read. NewReaderDict is typically used
+// to read data compressed by NewWriterDict.
+//
+// The ReadCloser returned by NewReader also implements Resetter.
+func NewReaderDict(r io.Reader, dict []byte) io.ReadCloser {
+ fixedHuffmanDecoderInit()
+
+ var f decompressor
+ f.r = makeReader(r)
+ f.bits = new([maxNumLit + maxNumDist]int)
+ f.codebits = new([numCodes]int)
+ f.step = (*decompressor).nextBlock
+ f.dict.init(maxMatchOffset, dict)
+ return &f
+}
diff --git a/vendor/github.com/klauspost/compress/flate/reverse_bits.go b/vendor/github.com/klauspost/compress/flate/reverse_bits.go
new file mode 100644
index 000000000..c1a02720d
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/reverse_bits.go
@@ -0,0 +1,48 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+var reverseByte = [256]byte{
+ 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
+ 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
+ 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
+ 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
+ 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
+ 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
+ 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
+ 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
+ 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
+ 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
+ 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
+ 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
+ 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
+ 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
+ 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
+ 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
+ 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
+ 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
+ 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
+ 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
+ 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
+ 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
+ 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
+ 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
+ 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
+ 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
+ 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
+ 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
+ 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
+ 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
+ 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
+ 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
+}
+
+func reverseUint16(v uint16) uint16 {
+ return uint16(reverseByte[v>>8]) | uint16(reverseByte[v&0xFF])<<8
+}
+
+func reverseBits(number uint16, bitLength byte) uint16 {
+ return reverseUint16(number << uint8(16-bitLength))
+}
diff --git a/vendor/github.com/klauspost/compress/flate/snappy.go b/vendor/github.com/klauspost/compress/flate/snappy.go
new file mode 100644
index 000000000..d853320a7
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/snappy.go
@@ -0,0 +1,900 @@
+// Copyright 2011 The Snappy-Go Authors. All rights reserved.
+// Modified for deflate by Klaus Post (c) 2015.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// emitLiteral writes a literal chunk and returns the number of bytes written.
+func emitLiteral(dst *tokens, lit []byte) {
+ ol := int(dst.n)
+ for i, v := range lit {
+ dst.tokens[(i+ol)&maxStoreBlockSize] = token(v)
+ }
+ dst.n += uint16(len(lit))
+}
+
+// emitCopy writes a copy chunk and returns the number of bytes written.
+func emitCopy(dst *tokens, offset, length int) {
+ dst.tokens[dst.n] = matchToken(uint32(length-3), uint32(offset-minOffsetSize))
+ dst.n++
+}
+
+type snappyEnc interface {
+ Encode(dst *tokens, src []byte)
+ Reset()
+}
+
+func newSnappy(level int) snappyEnc {
+ switch level {
+ case 1:
+ return &snappyL1{}
+ case 2:
+ return &snappyL2{snappyGen: snappyGen{cur: maxStoreBlockSize, prev: make([]byte, 0, maxStoreBlockSize)}}
+ case 3:
+ return &snappyL3{snappyGen: snappyGen{cur: maxStoreBlockSize, prev: make([]byte, 0, maxStoreBlockSize)}}
+ case 4:
+ return &snappyL4{snappyL3{snappyGen: snappyGen{cur: maxStoreBlockSize, prev: make([]byte, 0, maxStoreBlockSize)}}}
+ default:
+ panic("invalid level specified")
+ }
+}
+
+const (
+ tableBits = 14 // Bits used in the table
+ tableSize = 1 << tableBits // Size of the table
+ tableMask = tableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
+ tableShift = 32 - tableBits // Right-shift to get the tableBits most significant bits of a uint32.
+ baseMatchOffset = 1 // The smallest match offset
+ baseMatchLength = 3 // The smallest match length per the RFC section 3.2.5
+ maxMatchOffset = 1 << 15 // The largest match offset
+)
+
+func load32(b []byte, i int) uint32 {
+ b = b[i : i+4 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+ return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load64(b []byte, i int) uint64 {
+ b = b[i : i+8 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+ return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+ uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func hash(u uint32) uint32 {
+ return (u * 0x1e35a7bd) >> tableShift
+}
+
+// snappyL1 encapsulates level 1 compression
+type snappyL1 struct{}
+
+func (e *snappyL1) Reset() {}
+
+func (e *snappyL1) Encode(dst *tokens, src []byte) {
+ const (
+ inputMargin = 16 - 1
+ minNonLiteralBlockSize = 1 + 1 + inputMargin
+ )
+
+ // This check isn't in the Snappy implementation, but there, the caller
+ // instead of the callee handles this case.
+ if len(src) < minNonLiteralBlockSize {
+ // We do not fill the token table.
+ // This will be picked up by caller.
+ dst.n = uint16(len(src))
+ return
+ }
+
+ // Initialize the hash table.
+ //
+ // The table element type is uint16, as s < sLimit and sLimit < len(src)
+ // and len(src) <= maxStoreBlockSize and maxStoreBlockSize == 65535.
+ var table [tableSize]uint16
+
+ // sLimit is when to stop looking for offset/length copies. The inputMargin
+ // lets us use a fast path for emitLiteral in the main loop, while we are
+ // looking for copies.
+ sLimit := len(src) - inputMargin
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := 0
+
+ // The encoded form must start with a literal, as there are no previous
+ // bytes to copy, so we start looking for hash matches at s == 1.
+ s := 1
+ nextHash := hash(load32(src, s))
+
+ for {
+ // Copied from the C++ snappy implementation:
+ //
+ // Heuristic match skipping: If 32 bytes are scanned with no matches
+ // found, start looking only at every other byte. If 32 more bytes are
+ // scanned (or skipped), look at every third byte, etc.. When a match
+ // is found, immediately go back to looking at every byte. This is a
+ // small loss (~5% performance, ~0.1% density) for compressible data
+ // due to more bookkeeping, but for non-compressible data (such as
+ // JPEG) it's a huge win since the compressor quickly "realizes" the
+ // data is incompressible and doesn't bother looking for matches
+ // everywhere.
+ //
+ // The "skip" variable keeps track of how many bytes there are since
+ // the last match; dividing it by 32 (ie. right-shifting by five) gives
+ // the number of bytes to move ahead for each iteration.
+ skip := 32
+
+ nextS := s
+ candidate := 0
+ for {
+ s = nextS
+ bytesBetweenHashLookups := skip >> 5
+ nextS = s + bytesBetweenHashLookups
+ skip += bytesBetweenHashLookups
+ if nextS > sLimit {
+ goto emitRemainder
+ }
+ candidate = int(table[nextHash&tableMask])
+ table[nextHash&tableMask] = uint16(s)
+ nextHash = hash(load32(src, nextS))
+ if s-candidate <= maxMatchOffset && load32(src, s) == load32(src, candidate) {
+ break
+ }
+ }
+
+ // A 4-byte match has been found. We'll later see if more than 4 bytes
+ // match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+ // them as literal bytes.
+ emitLiteral(dst, src[nextEmit:s])
+
+ // Call emitCopy, and then see if another emitCopy could be our next
+ // move. Repeat until we find no match for the input immediately after
+ // what was consumed by the last emitCopy call.
+ //
+ // If we exit this loop normally then we need to call emitLiteral next,
+ // though we don't yet know how big the literal will be. We handle that
+ // by proceeding to the next iteration of the main loop. We also can
+ // exit this loop via goto if we get close to exhausting the input.
+ for {
+ // Invariant: we have a 4-byte match at s, and no need to emit any
+ // literal bytes prior to s.
+ base := s
+
+ // Extend the 4-byte match as long as possible.
+ //
+ // This is an inlined version of Snappy's:
+ // s = extendMatch(src, candidate+4, s+4)
+ s += 4
+ s1 := base + maxMatchLength
+ if s1 > len(src) {
+ s1 = len(src)
+ }
+ a := src[s:s1]
+ b := src[candidate+4:]
+ b = b[:len(a)]
+ l := len(a)
+ for i := range a {
+ if a[i] != b[i] {
+ l = i
+ break
+ }
+ }
+ s += l
+
+ // matchToken is flate's equivalent of Snappy's emitCopy.
+ dst.tokens[dst.n] = matchToken(uint32(s-base-baseMatchLength), uint32(base-candidate-baseMatchOffset))
+ dst.n++
+ nextEmit = s
+ if s >= sLimit {
+ goto emitRemainder
+ }
+
+ // We could immediately start working at s now, but to improve
+ // compression we first update the hash table at s-1 and at s. If
+ // another emitCopy is not our next move, also calculate nextHash
+ // at s+1. At least on GOARCH=amd64, these three hash calculations
+ // are faster as one load64 call (with some shifts) instead of
+ // three load32 calls.
+ x := load64(src, s-1)
+ prevHash := hash(uint32(x >> 0))
+ table[prevHash&tableMask] = uint16(s - 1)
+ currHash := hash(uint32(x >> 8))
+ candidate = int(table[currHash&tableMask])
+ table[currHash&tableMask] = uint16(s)
+ if s-candidate > maxMatchOffset || uint32(x>>8) != load32(src, candidate) {
+ nextHash = hash(uint32(x >> 16))
+ s++
+ break
+ }
+ }
+ }
+
+emitRemainder:
+ if nextEmit < len(src) {
+ emitLiteral(dst, src[nextEmit:])
+ }
+}
+
+type tableEntry struct {
+ val uint32
+ offset int32
+}
+
+func load3232(b []byte, i int32) uint32 {
+ b = b[i : i+4 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+ return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load6432(b []byte, i int32) uint64 {
+ b = b[i : i+8 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+ return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+ uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+// snappyGen maintains the table for matches,
+// and the previous byte block for level 2.
+// This is the generic implementation.
+type snappyGen struct {
+ prev []byte
+ cur int32
+}
+
+// snappyGen maintains the table for matches,
+// and the previous byte block for level 2.
+// This is the generic implementation.
+type snappyL2 struct {
+ snappyGen
+ table [tableSize]tableEntry
+}
+
+// EncodeL2 uses a similar algorithm to level 1, but is capable
+// of matching across blocks giving better compression at a small slowdown.
+func (e *snappyL2) Encode(dst *tokens, src []byte) {
+ const (
+ inputMargin = 8 - 1
+ minNonLiteralBlockSize = 1 + 1 + inputMargin
+ )
+
+ // Protect against e.cur wraparound.
+ if e.cur > 1<<30 {
+ for i := range e.table[:] {
+ e.table[i] = tableEntry{}
+ }
+ e.cur = maxStoreBlockSize
+ }
+
+ // This check isn't in the Snappy implementation, but there, the caller
+ // instead of the callee handles this case.
+ if len(src) < minNonLiteralBlockSize {
+ // We do not fill the token table.
+ // This will be picked up by caller.
+ dst.n = uint16(len(src))
+ e.cur += maxStoreBlockSize
+ e.prev = e.prev[:0]
+ return
+ }
+
+ // sLimit is when to stop looking for offset/length copies. The inputMargin
+ // lets us use a fast path for emitLiteral in the main loop, while we are
+ // looking for copies.
+ sLimit := int32(len(src) - inputMargin)
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := int32(0)
+ s := int32(0)
+ cv := load3232(src, s)
+ nextHash := hash(cv)
+
+ for {
+ // Copied from the C++ snappy implementation:
+ //
+ // Heuristic match skipping: If 32 bytes are scanned with no matches
+ // found, start looking only at every other byte. If 32 more bytes are
+ // scanned (or skipped), look at every third byte, etc.. When a match
+ // is found, immediately go back to looking at every byte. This is a
+ // small loss (~5% performance, ~0.1% density) for compressible data
+ // due to more bookkeeping, but for non-compressible data (such as
+ // JPEG) it's a huge win since the compressor quickly "realizes" the
+ // data is incompressible and doesn't bother looking for matches
+ // everywhere.
+ //
+ // The "skip" variable keeps track of how many bytes there are since
+ // the last match; dividing it by 32 (ie. right-shifting by five) gives
+ // the number of bytes to move ahead for each iteration.
+ skip := int32(32)
+
+ nextS := s
+ var candidate tableEntry
+ for {
+ s = nextS
+ bytesBetweenHashLookups := skip >> 5
+ nextS = s + bytesBetweenHashLookups
+ skip += bytesBetweenHashLookups
+ if nextS > sLimit {
+ goto emitRemainder
+ }
+ candidate = e.table[nextHash&tableMask]
+ now := load3232(src, nextS)
+ e.table[nextHash&tableMask] = tableEntry{offset: s + e.cur, val: cv}
+ nextHash = hash(now)
+
+ offset := s - (candidate.offset - e.cur)
+ if offset > maxMatchOffset || cv != candidate.val {
+ // Out of range or not matched.
+ cv = now
+ continue
+ }
+ break
+ }
+
+ // A 4-byte match has been found. We'll later see if more than 4 bytes
+ // match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+ // them as literal bytes.
+ emitLiteral(dst, src[nextEmit:s])
+
+ // Call emitCopy, and then see if another emitCopy could be our next
+ // move. Repeat until we find no match for the input immediately after
+ // what was consumed by the last emitCopy call.
+ //
+ // If we exit this loop normally then we need to call emitLiteral next,
+ // though we don't yet know how big the literal will be. We handle that
+ // by proceeding to the next iteration of the main loop. We also can
+ // exit this loop via goto if we get close to exhausting the input.
+ for {
+ // Invariant: we have a 4-byte match at s, and no need to emit any
+ // literal bytes prior to s.
+
+ // Extend the 4-byte match as long as possible.
+ //
+ s += 4
+ t := candidate.offset - e.cur + 4
+ l := e.matchlen(s, t, src)
+
+ // matchToken is flate's equivalent of Snappy's emitCopy. (length,offset)
+ dst.tokens[dst.n] = matchToken(uint32(l+4-baseMatchLength), uint32(s-t-baseMatchOffset))
+ dst.n++
+ s += l
+ nextEmit = s
+ if s >= sLimit {
+ t += l
+ // Index first pair after match end.
+ if int(t+4) < len(src) && t > 0 {
+ cv := load3232(src, t)
+ e.table[hash(cv)&tableMask] = tableEntry{offset: t + e.cur, val: cv}
+ }
+ goto emitRemainder
+ }
+
+ // We could immediately start working at s now, but to improve
+ // compression we first update the hash table at s-1 and at s. If
+ // another emitCopy is not our next move, also calculate nextHash
+ // at s+1. At least on GOARCH=amd64, these three hash calculations
+ // are faster as one load64 call (with some shifts) instead of
+ // three load32 calls.
+ x := load6432(src, s-1)
+ prevHash := hash(uint32(x))
+ e.table[prevHash&tableMask] = tableEntry{offset: e.cur + s - 1, val: uint32(x)}
+ x >>= 8
+ currHash := hash(uint32(x))
+ candidate = e.table[currHash&tableMask]
+ e.table[currHash&tableMask] = tableEntry{offset: e.cur + s, val: uint32(x)}
+
+ offset := s - (candidate.offset - e.cur)
+ if offset > maxMatchOffset || uint32(x) != candidate.val {
+ cv = uint32(x >> 8)
+ nextHash = hash(cv)
+ s++
+ break
+ }
+ }
+ }
+
+emitRemainder:
+ if int(nextEmit) < len(src) {
+ emitLiteral(dst, src[nextEmit:])
+ }
+ e.cur += int32(len(src))
+ e.prev = e.prev[:len(src)]
+ copy(e.prev, src)
+}
+
+type tableEntryPrev struct {
+ Cur tableEntry
+ Prev tableEntry
+}
+
+// snappyL3
+type snappyL3 struct {
+ snappyGen
+ table [tableSize]tableEntryPrev
+}
+
+// Encode uses a similar algorithm to level 2, will check up to two candidates.
+func (e *snappyL3) Encode(dst *tokens, src []byte) {
+ const (
+ inputMargin = 8 - 1
+ minNonLiteralBlockSize = 1 + 1 + inputMargin
+ )
+
+ // Protect against e.cur wraparound.
+ if e.cur > 1<<30 {
+ for i := range e.table[:] {
+ e.table[i] = tableEntryPrev{}
+ }
+ e.snappyGen = snappyGen{cur: maxStoreBlockSize, prev: e.prev[:0]}
+ }
+
+ // This check isn't in the Snappy implementation, but there, the caller
+ // instead of the callee handles this case.
+ if len(src) < minNonLiteralBlockSize {
+ // We do not fill the token table.
+ // This will be picked up by caller.
+ dst.n = uint16(len(src))
+ e.cur += maxStoreBlockSize
+ e.prev = e.prev[:0]
+ return
+ }
+
+ // sLimit is when to stop looking for offset/length copies. The inputMargin
+ // lets us use a fast path for emitLiteral in the main loop, while we are
+ // looking for copies.
+ sLimit := int32(len(src) - inputMargin)
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := int32(0)
+ s := int32(0)
+ cv := load3232(src, s)
+ nextHash := hash(cv)
+
+ for {
+ // Copied from the C++ snappy implementation:
+ //
+ // Heuristic match skipping: If 32 bytes are scanned with no matches
+ // found, start looking only at every other byte. If 32 more bytes are
+ // scanned (or skipped), look at every third byte, etc.. When a match
+ // is found, immediately go back to looking at every byte. This is a
+ // small loss (~5% performance, ~0.1% density) for compressible data
+ // due to more bookkeeping, but for non-compressible data (such as
+ // JPEG) it's a huge win since the compressor quickly "realizes" the
+ // data is incompressible and doesn't bother looking for matches
+ // everywhere.
+ //
+ // The "skip" variable keeps track of how many bytes there are since
+ // the last match; dividing it by 32 (ie. right-shifting by five) gives
+ // the number of bytes to move ahead for each iteration.
+ skip := int32(32)
+
+ nextS := s
+ var candidate tableEntry
+ for {
+ s = nextS
+ bytesBetweenHashLookups := skip >> 5
+ nextS = s + bytesBetweenHashLookups
+ skip += bytesBetweenHashLookups
+ if nextS > sLimit {
+ goto emitRemainder
+ }
+ candidates := e.table[nextHash&tableMask]
+ now := load3232(src, nextS)
+ e.table[nextHash&tableMask] = tableEntryPrev{Prev: candidates.Cur, Cur: tableEntry{offset: s + e.cur, val: cv}}
+ nextHash = hash(now)
+
+ // Check both candidates
+ candidate = candidates.Cur
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset <= maxMatchOffset {
+ break
+ }
+ } else {
+ // We only check if value mismatches.
+ // Offset will always be invalid in other cases.
+ candidate = candidates.Prev
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset <= maxMatchOffset {
+ break
+ }
+ }
+ }
+ cv = now
+ }
+
+ // A 4-byte match has been found. We'll later see if more than 4 bytes
+ // match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+ // them as literal bytes.
+ emitLiteral(dst, src[nextEmit:s])
+
+ // Call emitCopy, and then see if another emitCopy could be our next
+ // move. Repeat until we find no match for the input immediately after
+ // what was consumed by the last emitCopy call.
+ //
+ // If we exit this loop normally then we need to call emitLiteral next,
+ // though we don't yet know how big the literal will be. We handle that
+ // by proceeding to the next iteration of the main loop. We also can
+ // exit this loop via goto if we get close to exhausting the input.
+ for {
+ // Invariant: we have a 4-byte match at s, and no need to emit any
+ // literal bytes prior to s.
+
+ // Extend the 4-byte match as long as possible.
+ //
+ s += 4
+ t := candidate.offset - e.cur + 4
+ l := e.matchlen(s, t, src)
+
+ // matchToken is flate's equivalent of Snappy's emitCopy. (length,offset)
+ dst.tokens[dst.n] = matchToken(uint32(l+4-baseMatchLength), uint32(s-t-baseMatchOffset))
+ dst.n++
+ s += l
+ nextEmit = s
+ if s >= sLimit {
+ t += l
+ // Index first pair after match end.
+ if int(t+4) < len(src) && t > 0 {
+ cv := load3232(src, t)
+ nextHash = hash(cv)
+ e.table[nextHash&tableMask] = tableEntryPrev{
+ Prev: e.table[nextHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + t, val: cv},
+ }
+ }
+ goto emitRemainder
+ }
+
+ // We could immediately start working at s now, but to improve
+ // compression we first update the hash table at s-3 to s. If
+ // another emitCopy is not our next move, also calculate nextHash
+ // at s+1. At least on GOARCH=amd64, these three hash calculations
+ // are faster as one load64 call (with some shifts) instead of
+ // three load32 calls.
+ x := load6432(src, s-3)
+ prevHash := hash(uint32(x))
+ e.table[prevHash&tableMask] = tableEntryPrev{
+ Prev: e.table[prevHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + s - 3, val: uint32(x)},
+ }
+ x >>= 8
+ prevHash = hash(uint32(x))
+
+ e.table[prevHash&tableMask] = tableEntryPrev{
+ Prev: e.table[prevHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + s - 2, val: uint32(x)},
+ }
+ x >>= 8
+ prevHash = hash(uint32(x))
+
+ e.table[prevHash&tableMask] = tableEntryPrev{
+ Prev: e.table[prevHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + s - 1, val: uint32(x)},
+ }
+ x >>= 8
+ currHash := hash(uint32(x))
+ candidates := e.table[currHash&tableMask]
+ cv = uint32(x)
+ e.table[currHash&tableMask] = tableEntryPrev{
+ Prev: candidates.Cur,
+ Cur: tableEntry{offset: s + e.cur, val: cv},
+ }
+
+ // Check both candidates
+ candidate = candidates.Cur
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset <= maxMatchOffset {
+ continue
+ }
+ } else {
+ // We only check if value mismatches.
+ // Offset will always be invalid in other cases.
+ candidate = candidates.Prev
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset <= maxMatchOffset {
+ continue
+ }
+ }
+ }
+ cv = uint32(x >> 8)
+ nextHash = hash(cv)
+ s++
+ break
+ }
+ }
+
+emitRemainder:
+ if int(nextEmit) < len(src) {
+ emitLiteral(dst, src[nextEmit:])
+ }
+ e.cur += int32(len(src))
+ e.prev = e.prev[:len(src)]
+ copy(e.prev, src)
+}
+
+// snappyL4
+type snappyL4 struct {
+ snappyL3
+}
+
+// Encode uses a similar algorithm to level 3,
+// but will check up to two candidates if first isn't long enough.
+func (e *snappyL4) Encode(dst *tokens, src []byte) {
+ const (
+ inputMargin = 8 - 3
+ minNonLiteralBlockSize = 1 + 1 + inputMargin
+ matchLenGood = 12
+ )
+
+ // Protect against e.cur wraparound.
+ if e.cur > 1<<30 {
+ for i := range e.table[:] {
+ e.table[i] = tableEntryPrev{}
+ }
+ e.snappyGen = snappyGen{cur: maxStoreBlockSize, prev: e.prev[:0]}
+ }
+
+ // This check isn't in the Snappy implementation, but there, the caller
+ // instead of the callee handles this case.
+ if len(src) < minNonLiteralBlockSize {
+ // We do not fill the token table.
+ // This will be picked up by caller.
+ dst.n = uint16(len(src))
+ e.cur += maxStoreBlockSize
+ e.prev = e.prev[:0]
+ return
+ }
+
+ // sLimit is when to stop looking for offset/length copies. The inputMargin
+ // lets us use a fast path for emitLiteral in the main loop, while we are
+ // looking for copies.
+ sLimit := int32(len(src) - inputMargin)
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := int32(0)
+ s := int32(0)
+ cv := load3232(src, s)
+ nextHash := hash(cv)
+
+ for {
+ // Copied from the C++ snappy implementation:
+ //
+ // Heuristic match skipping: If 32 bytes are scanned with no matches
+ // found, start looking only at every other byte. If 32 more bytes are
+ // scanned (or skipped), look at every third byte, etc.. When a match
+ // is found, immediately go back to looking at every byte. This is a
+ // small loss (~5% performance, ~0.1% density) for compressible data
+ // due to more bookkeeping, but for non-compressible data (such as
+ // JPEG) it's a huge win since the compressor quickly "realizes" the
+ // data is incompressible and doesn't bother looking for matches
+ // everywhere.
+ //
+ // The "skip" variable keeps track of how many bytes there are since
+ // the last match; dividing it by 32 (ie. right-shifting by five) gives
+ // the number of bytes to move ahead for each iteration.
+ skip := int32(32)
+
+ nextS := s
+ var candidate tableEntry
+ var candidateAlt tableEntry
+ for {
+ s = nextS
+ bytesBetweenHashLookups := skip >> 5
+ nextS = s + bytesBetweenHashLookups
+ skip += bytesBetweenHashLookups
+ if nextS > sLimit {
+ goto emitRemainder
+ }
+ candidates := e.table[nextHash&tableMask]
+ now := load3232(src, nextS)
+ e.table[nextHash&tableMask] = tableEntryPrev{Prev: candidates.Cur, Cur: tableEntry{offset: s + e.cur, val: cv}}
+ nextHash = hash(now)
+
+ // Check both candidates
+ candidate = candidates.Cur
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset < maxMatchOffset {
+ offset = s - (candidates.Prev.offset - e.cur)
+ if cv == candidates.Prev.val && offset < maxMatchOffset {
+ candidateAlt = candidates.Prev
+ }
+ break
+ }
+ } else {
+ // We only check if value mismatches.
+ // Offset will always be invalid in other cases.
+ candidate = candidates.Prev
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset < maxMatchOffset {
+ break
+ }
+ }
+ }
+ cv = now
+ }
+
+ // A 4-byte match has been found. We'll later see if more than 4 bytes
+ // match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+ // them as literal bytes.
+ emitLiteral(dst, src[nextEmit:s])
+
+ // Call emitCopy, and then see if another emitCopy could be our next
+ // move. Repeat until we find no match for the input immediately after
+ // what was consumed by the last emitCopy call.
+ //
+ // If we exit this loop normally then we need to call emitLiteral next,
+ // though we don't yet know how big the literal will be. We handle that
+ // by proceeding to the next iteration of the main loop. We also can
+ // exit this loop via goto if we get close to exhausting the input.
+ for {
+ // Invariant: we have a 4-byte match at s, and no need to emit any
+ // literal bytes prior to s.
+
+ // Extend the 4-byte match as long as possible.
+ //
+ s += 4
+ t := candidate.offset - e.cur + 4
+ l := e.matchlen(s, t, src)
+ // Try alternative candidate if match length < matchLenGood.
+ if l < matchLenGood-4 && candidateAlt.offset != 0 {
+ t2 := candidateAlt.offset - e.cur + 4
+ l2 := e.matchlen(s, t2, src)
+ if l2 > l {
+ l = l2
+ t = t2
+ }
+ }
+ // matchToken is flate's equivalent of Snappy's emitCopy. (length,offset)
+ dst.tokens[dst.n] = matchToken(uint32(l+4-baseMatchLength), uint32(s-t-baseMatchOffset))
+ dst.n++
+ s += l
+ nextEmit = s
+ if s >= sLimit {
+ t += l
+ // Index first pair after match end.
+ if int(t+4) < len(src) && t > 0 {
+ cv := load3232(src, t)
+ nextHash = hash(cv)
+ e.table[nextHash&tableMask] = tableEntryPrev{
+ Prev: e.table[nextHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + t, val: cv},
+ }
+ }
+ goto emitRemainder
+ }
+
+ // We could immediately start working at s now, but to improve
+ // compression we first update the hash table at s-3 to s. If
+ // another emitCopy is not our next move, also calculate nextHash
+ // at s+1. At least on GOARCH=amd64, these three hash calculations
+ // are faster as one load64 call (with some shifts) instead of
+ // three load32 calls.
+ x := load6432(src, s-3)
+ prevHash := hash(uint32(x))
+ e.table[prevHash&tableMask] = tableEntryPrev{
+ Prev: e.table[prevHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + s - 3, val: uint32(x)},
+ }
+ x >>= 8
+ prevHash = hash(uint32(x))
+
+ e.table[prevHash&tableMask] = tableEntryPrev{
+ Prev: e.table[prevHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + s - 2, val: uint32(x)},
+ }
+ x >>= 8
+ prevHash = hash(uint32(x))
+
+ e.table[prevHash&tableMask] = tableEntryPrev{
+ Prev: e.table[prevHash&tableMask].Cur,
+ Cur: tableEntry{offset: e.cur + s - 1, val: uint32(x)},
+ }
+ x >>= 8
+ currHash := hash(uint32(x))
+ candidates := e.table[currHash&tableMask]
+ cv = uint32(x)
+ e.table[currHash&tableMask] = tableEntryPrev{
+ Prev: candidates.Cur,
+ Cur: tableEntry{offset: s + e.cur, val: cv},
+ }
+
+ // Check both candidates
+ candidate = candidates.Cur
+ candidateAlt = tableEntry{}
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset <= maxMatchOffset {
+ offset = s - (candidates.Prev.offset - e.cur)
+ if cv == candidates.Prev.val && offset <= maxMatchOffset {
+ candidateAlt = candidates.Prev
+ }
+ continue
+ }
+ } else {
+ // We only check if value mismatches.
+ // Offset will always be invalid in other cases.
+ candidate = candidates.Prev
+ if cv == candidate.val {
+ offset := s - (candidate.offset - e.cur)
+ if offset <= maxMatchOffset {
+ continue
+ }
+ }
+ }
+ cv = uint32(x >> 8)
+ nextHash = hash(cv)
+ s++
+ break
+ }
+ }
+
+emitRemainder:
+ if int(nextEmit) < len(src) {
+ emitLiteral(dst, src[nextEmit:])
+ }
+ e.cur += int32(len(src))
+ e.prev = e.prev[:len(src)]
+ copy(e.prev, src)
+}
+
+func (e *snappyGen) matchlen(s, t int32, src []byte) int32 {
+ s1 := int(s) + maxMatchLength - 4
+ if s1 > len(src) {
+ s1 = len(src)
+ }
+
+ // If we are inside the current block
+ if t >= 0 {
+ b := src[t:]
+ a := src[s:s1]
+ b = b[:len(a)]
+ // Extend the match to be as long as possible.
+ for i := range a {
+ if a[i] != b[i] {
+ return int32(i)
+ }
+ }
+ return int32(len(a))
+ }
+
+ // We found a match in the previous block.
+ tp := int32(len(e.prev)) + t
+ if tp < 0 {
+ return 0
+ }
+
+ // Extend the match to be as long as possible.
+ a := src[s:s1]
+ b := e.prev[tp:]
+ if len(b) > len(a) {
+ b = b[:len(a)]
+ }
+ a = a[:len(b)]
+ for i := range b {
+ if a[i] != b[i] {
+ return int32(i)
+ }
+ }
+
+ // If we reached our limit, we matched everything we are
+ // allowed to in the previous block and we return.
+ n := int32(len(b))
+ if int(s+n) == s1 {
+ return n
+ }
+
+ // Continue looking for more matches in the current block.
+ a = src[s+n : s1]
+ b = src[:len(a)]
+ for i := range a {
+ if a[i] != b[i] {
+ return int32(i) + n
+ }
+ }
+ return int32(len(a)) + n
+}
+
+// Reset the encoding table.
+func (e *snappyGen) Reset() {
+ e.prev = e.prev[:0]
+ e.cur += maxMatchOffset
+}
diff --git a/vendor/github.com/klauspost/compress/flate/token.go b/vendor/github.com/klauspost/compress/flate/token.go
new file mode 100644
index 000000000..4f275ea61
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/flate/token.go
@@ -0,0 +1,115 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import "fmt"
+
+const (
+ // 2 bits: type 0 = literal 1=EOF 2=Match 3=Unused
+ // 8 bits: xlength = length - MIN_MATCH_LENGTH
+ // 22 bits xoffset = offset - MIN_OFFSET_SIZE, or literal
+ lengthShift = 22
+ offsetMask = 1<<lengthShift - 1
+ typeMask = 3 << 30
+ literalType = 0 << 30
+ matchType = 1 << 30
+)
+
+// The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH)
+// is lengthCodes[length - MIN_MATCH_LENGTH]
+var lengthCodes = [...]uint32{
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
+ 9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
+ 13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
+ 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
+ 17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
+ 18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
+ 19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
+ 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
+ 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
+ 21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
+ 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
+ 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
+ 23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
+ 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+ 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+ 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+ 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+ 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+ 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+ 25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
+ 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+ 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+ 26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
+ 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+ 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+ 27, 27, 27, 27, 27, 28,
+}
+
+var offsetCodes = [...]uint32{
+ 0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
+ 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
+ 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+ 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+ 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+ 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+ 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+ 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+}
+
+type token uint32
+
+type tokens struct {
+ tokens [maxStoreBlockSize + 1]token
+ n uint16 // Must be able to contain maxStoreBlockSize
+}
+
+// Convert a literal into a literal token.
+func literalToken(literal uint32) token { return token(literalType + literal) }
+
+// Convert a < xlength, xoffset > pair into a match token.
+func matchToken(xlength uint32, xoffset uint32) token {
+ return token(matchType + xlength<<lengthShift + xoffset)
+}
+
+func matchTokend(xlength uint32, xoffset uint32) token {
+ if xlength > maxMatchLength || xoffset > maxMatchOffset {
+ panic(fmt.Sprintf("Invalid match: len: %d, offset: %d\n", xlength, xoffset))
+ return token(matchType)
+ }
+ return token(matchType + xlength<<lengthShift + xoffset)
+}
+
+// Returns the type of a token
+func (t token) typ() uint32 { return uint32(t) & typeMask }
+
+// Returns the literal of a literal token
+func (t token) literal() uint32 { return uint32(t - literalType) }
+
+// Returns the extra offset of a match token
+func (t token) offset() uint32 { return uint32(t) & offsetMask }
+
+func (t token) length() uint32 { return uint32((t - matchType) >> lengthShift) }
+
+func lengthCode(len uint32) uint32 { return lengthCodes[len] }
+
+// Returns the offset code corresponding to a specific offset
+func offsetCode(off uint32) uint32 {
+ if off < uint32(len(offsetCodes)) {
+ return offsetCodes[off]
+ } else if off>>7 < uint32(len(offsetCodes)) {
+ return offsetCodes[off>>7] + 14
+ } else {
+ return offsetCodes[off>>14] + 28
+ }
+}
generated by cgit v1.2.3-54-g00ecf (git 2.39.0) at 2024-12-29 09:22:41 +0000