forgejo-federation/vendor/github.com/klauspost/compress/zstd/enc_base.go
6543 12a1f914f4
Vendor Update Go Libs (#13166)
* update github.com/alecthomas/chroma v0.8.0 -> v0.8.1

* github.com/blevesearch/bleve v1.0.10 -> v1.0.12

* editorconfig-core-go v2.1.1 -> v2.3.7

* github.com/gliderlabs/ssh v0.2.2 -> v0.3.1

* migrate editorconfig.ParseBytes to Parse

* github.com/shurcooL/vfsgen to 0d455de96546

* github.com/go-git/go-git/v5 v5.1.0 -> v5.2.0

* github.com/google/uuid v1.1.1 -> v1.1.2

* github.com/huandu/xstrings v1.3.0 -> v1.3.2

* github.com/klauspost/compress v1.10.11 -> v1.11.1

* github.com/markbates/goth v1.61.2 -> v1.65.0

* github.com/mattn/go-sqlite3 v1.14.0 -> v1.14.4

* github.com/mholt/archiver v3.3.0 -> v3.3.2

* github.com/microcosm-cc/bluemonday 4f7140c49acb -> v1.0.4

* github.com/minio/minio-go v7.0.4 -> v7.0.5

* github.com/olivere/elastic v7.0.9 -> v7.0.20

* github.com/urfave/cli v1.20.0 -> v1.22.4

* github.com/prometheus/client_golang v1.1.0 -> v1.8.0

* github.com/xanzy/go-gitlab v0.37.0 -> v0.38.1

* mvdan.cc/xurls v2.1.0 -> v2.2.0

Co-authored-by: Lauris BH <lauris@nix.lv>
2020-10-16 01:06:27 -04:00

155 lines
3.7 KiB
Go
Vendored

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...)
}
}