1 files changed, 155 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/enc_base.go b/vendor/github.com/klauspost/compress/zstd/enc_base.go
new file mode 100644
index 000000000..b1b7c6e6a
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/enc_base.go
@@ -0,0 +1,155 @@
+package zstd
+
+import (
+	"fmt"
+	"math/bits"
+
+	"github.com/klauspost/compress/zstd/internal/xxhash"
+)
+
+type fastBase struct {
+	// cur is the offset at the start of hist
+	cur int32
+	// maximum offset. Should be at least 2x block size.
+	maxMatchOff int32
+	hist        []byte
+	crc         *xxhash.Digest
+	tmp         [8]byte
+	blk         *blockEnc
+	lastDictID  uint32
+}
+
+// CRC returns the underlying CRC writer.
+func (e *fastBase) CRC() *xxhash.Digest {
+	return e.crc
+}
+
+// AppendCRC will append the CRC to the destination slice and return it.
+func (e *fastBase) AppendCRC(dst []byte) []byte {
+	crc := e.crc.Sum(e.tmp[:0])
+	dst = append(dst, crc[7], crc[6], crc[5], crc[4])
+	return dst
+}
+
+// WindowSize returns the window size of the encoder,
+// or a window size small enough to contain the input size, if > 0.
+func (e *fastBase) WindowSize(size int) int32 {
+	if size > 0 && size < int(e.maxMatchOff) {
+		b := int32(1) << uint(bits.Len(uint(size)))
+		// Keep minimum window.
+		if b < 1024 {
+			b = 1024
+		}
+		return b
+	}
+	return e.maxMatchOff
+}
+
+// Block returns the current block.
+func (e *fastBase) Block() *blockEnc {
+	return e.blk
+}
+
+func (e *fastBase) addBlock(src []byte) int32 {
+	if debugAsserts && e.cur > bufferReset {
+		panic(fmt.Sprintf("ecur (%d) > buffer reset (%d)", e.cur, bufferReset))
+	}
+	// check if we have space already
+	if len(e.hist)+len(src) > cap(e.hist) {
+		if cap(e.hist) == 0 {
+			l := e.maxMatchOff * 2
+			// Make it at least 1MB.
+			if l < 1<<20 {
+				l = 1 << 20
+			}
+			e.hist = make([]byte, 0, l)
+		} else {
+			if cap(e.hist) < int(e.maxMatchOff*2) {
+				panic("unexpected buffer size")
+			}
+			// Move down
+			offset := int32(len(e.hist)) - e.maxMatchOff
+			copy(e.hist[0:e.maxMatchOff], e.hist[offset:])
+			e.cur += offset
+			e.hist = e.hist[:e.maxMatchOff]
+		}
+	}
+	s := int32(len(e.hist))
+	e.hist = append(e.hist, src...)
+	return s
+}
+
+// useBlock will replace the block with the provided one,
+// but transfer recent offsets from the previous.
+func (e *fastBase) UseBlock(enc *blockEnc) {
+	enc.reset(e.blk)
+	e.blk = enc
+}
+
+func (e *fastBase) matchlenNoHist(s, t int32, src []byte) int32 {
+	// Extend the match to be as long as possible.
+	return int32(matchLen(src[s:], src[t:]))
+}
+
+func (e *fastBase) matchlen(s, t int32, src []byte) int32 {
+	if debugAsserts {
+		if s < 0 {
+			err := fmt.Sprintf("s (%d) < 0", s)
+			panic(err)
+		}
+		if t < 0 {
+			err := fmt.Sprintf("s (%d) < 0", s)
+			panic(err)
+		}
+		if s-t > e.maxMatchOff {
+			err := fmt.Sprintf("s (%d) - t (%d) > maxMatchOff (%d)", s, t, e.maxMatchOff)
+			panic(err)
+		}
+		if len(src)-int(s) > maxCompressedBlockSize {
+			panic(fmt.Sprintf("len(src)-s (%d) > maxCompressedBlockSize (%d)", len(src)-int(s), maxCompressedBlockSize))
+		}
+	}
+
+	// Extend the match to be as long as possible.
+	return int32(matchLen(src[s:], src[t:]))
+}
+
+// Reset the encoding table.
+func (e *fastBase) resetBase(d *dict, singleBlock bool) {
+	if e.blk == nil {
+		e.blk = &blockEnc{}
+		e.blk.init()
+	} else {
+		e.blk.reset(nil)
+	}
+	e.blk.initNewEncode()
+	if e.crc == nil {
+		e.crc = xxhash.New()
+	} else {
+		e.crc.Reset()
+	}
+	if (!singleBlock || d.DictContentSize() > 0) && cap(e.hist) < int(e.maxMatchOff*2)+d.DictContentSize() {
+		l := e.maxMatchOff*2 + int32(d.DictContentSize())
+		// Make it at least 1MB.
+		if l < 1<<20 {
+			l = 1 << 20
+		}
+		e.hist = make([]byte, 0, l)
+	}
+	// We offset current position so everything will be out of reach.
+	// If above reset line, history will be purged.
+	if e.cur < bufferReset {
+		e.cur += e.maxMatchOff + int32(len(e.hist))
+	}
+	e.hist = e.hist[:0]
+	if d != nil {
+		// Set offsets (currently not used)
+		for i, off := range d.offsets {
+			e.blk.recentOffsets[i] = uint32(off)
+			e.blk.prevRecentOffsets[i] = e.blk.recentOffsets[i]
+		}
+		// Transfer litenc.
+		e.blk.dictLitEnc = d.litEnc
+		e.hist = append(e.hist, d.content...)
+	}
+}