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authorDaniel J Walsh <dwalsh@redhat.com>2019-08-01 03:46:14 -0400
committerDaniel J Walsh <dwalsh@redhat.com>2019-08-01 03:46:14 -0400
commit9d6dce119949d340ebb42becae018a3c11148690 (patch)
treec0bb999f9bddbc9379f9f7b159194d35c077fb36 /vendor/github.com/klauspost/compress/huff0/bitwriter.go
parent39de184b8bfb14954f77190f0e6127c1ddc363c0 (diff)
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github.com/containers/storage v1.12.13
Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
Diffstat (limited to 'vendor/github.com/klauspost/compress/huff0/bitwriter.go')
-rw-r--r--vendor/github.com/klauspost/compress/huff0/bitwriter.go186
1 files changed, 186 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/huff0/bitwriter.go b/vendor/github.com/klauspost/compress/huff0/bitwriter.go
new file mode 100644
index 000000000..ec0c3fc53
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/huff0/bitwriter.go
@@ -0,0 +1,186 @@
+// Copyright 2018 Klaus Post. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
+
+package huff0
+
+import "fmt"
+
+// bitWriter will write bits.
+// First bit will be LSB of the first byte of output.
+type bitWriter struct {
+ bitContainer uint64
+ nBits uint8
+ out []byte
+}
+
+// bitMask16 is bitmasks. Has extra to avoid bounds check.
+var bitMask16 = [32]uint16{
+ 0, 1, 3, 7, 0xF, 0x1F,
+ 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
+ 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0xFFFF,
+ 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
+ 0xFFFF, 0xFFFF} /* up to 16 bits */
+
+// addBits16NC will add up to 16 bits.
+// It will not check if there is space for them,
+// so the caller must ensure that it has flushed recently.
+func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
+ b.bitContainer |= uint64(value&bitMask16[bits&31]) << (b.nBits & 63)
+ b.nBits += bits
+}
+
+// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
+// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
+func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {
+ b.bitContainer |= uint64(value) << (b.nBits & 63)
+ b.nBits += bits
+}
+
+// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
+// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
+func (b *bitWriter) encSymbol(ct cTable, symbol byte) {
+ enc := ct[symbol]
+ b.bitContainer |= uint64(enc.val) << (b.nBits & 63)
+ b.nBits += enc.nBits
+}
+
+// addBits16ZeroNC will add up to 16 bits.
+// It will not check if there is space for them,
+// so the caller must ensure that it has flushed recently.
+// This is fastest if bits can be zero.
+func (b *bitWriter) addBits16ZeroNC(value uint16, bits uint8) {
+ if bits == 0 {
+ return
+ }
+ value <<= (16 - bits) & 15
+ value >>= (16 - bits) & 15
+ b.bitContainer |= uint64(value) << (b.nBits & 63)
+ b.nBits += bits
+}
+
+// flush will flush all pending full bytes.
+// There will be at least 56 bits available for writing when this has been called.
+// Using flush32 is faster, but leaves less space for writing.
+func (b *bitWriter) flush() {
+ v := b.nBits >> 3
+ switch v {
+ case 0:
+ return
+ case 1:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ )
+ b.bitContainer >>= 1 << 3
+ case 2:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ )
+ b.bitContainer >>= 2 << 3
+ case 3:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ )
+ b.bitContainer >>= 3 << 3
+ case 4:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ byte(b.bitContainer>>24),
+ )
+ b.bitContainer >>= 4 << 3
+ case 5:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ byte(b.bitContainer>>24),
+ byte(b.bitContainer>>32),
+ )
+ b.bitContainer >>= 5 << 3
+ case 6:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ byte(b.bitContainer>>24),
+ byte(b.bitContainer>>32),
+ byte(b.bitContainer>>40),
+ )
+ b.bitContainer >>= 6 << 3
+ case 7:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ byte(b.bitContainer>>24),
+ byte(b.bitContainer>>32),
+ byte(b.bitContainer>>40),
+ byte(b.bitContainer>>48),
+ )
+ b.bitContainer >>= 7 << 3
+ case 8:
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ byte(b.bitContainer>>24),
+ byte(b.bitContainer>>32),
+ byte(b.bitContainer>>40),
+ byte(b.bitContainer>>48),
+ byte(b.bitContainer>>56),
+ )
+ b.bitContainer = 0
+ b.nBits = 0
+ return
+ default:
+ panic(fmt.Errorf("bits (%d) > 64", b.nBits))
+ }
+ b.nBits &= 7
+}
+
+// flush32 will flush out, so there are at least 32 bits available for writing.
+func (b *bitWriter) flush32() {
+ if b.nBits < 32 {
+ return
+ }
+ b.out = append(b.out,
+ byte(b.bitContainer),
+ byte(b.bitContainer>>8),
+ byte(b.bitContainer>>16),
+ byte(b.bitContainer>>24))
+ b.nBits -= 32
+ b.bitContainer >>= 32
+}
+
+// flushAlign will flush remaining full bytes and align to next byte boundary.
+func (b *bitWriter) flushAlign() {
+ nbBytes := (b.nBits + 7) >> 3
+ for i := uint8(0); i < nbBytes; i++ {
+ b.out = append(b.out, byte(b.bitContainer>>(i*8)))
+ }
+ b.nBits = 0
+ b.bitContainer = 0
+}
+
+// close will write the alignment bit and write the final byte(s)
+// to the output.
+func (b *bitWriter) close() error {
+ // End mark
+ b.addBits16Clean(1, 1)
+ // flush until next byte.
+ b.flushAlign()
+ return nil
+}
+
+// reset and continue writing by appending to out.
+func (b *bitWriter) reset(out []byte) {
+ b.bitContainer = 0
+ b.nBits = 0
+ b.out = out
+}