gitea/vendor/github.com/klauspost/compress/zstd/enc_base.go
6543 792b4dba2c
[Vendor] Update directly used dependencys (#15593)
* update github.com/blevesearch/bleve v2.0.2 -> v2.0.3

* github.com/denisenkom/go-mssqldb v0.9.0 -> v0.10.0

* github.com/editorconfig/editorconfig-core-go v2.4.1 -> v2.4.2

* github.com/go-chi/cors v1.1.1 -> v1.2.0

* github.com/go-git/go-billy v5.0.0 -> v5.1.0

* github.com/go-git/go-git v5.2.0 -> v5.3.0

* github.com/go-ldap/ldap v3.2.4 -> v3.3.0

* github.com/go-redis/redis v8.6.0 -> v8.8.2

* github.com/go-sql-driver/mysql v1.5.0 -> v1.6.0

* github.com/go-swagger/go-swagger v0.26.1 -> v0.27.0

* github.com/lib/pq v1.9.0 -> v1.10.1

* github.com/mattn/go-sqlite3 v1.14.6 -> v1.14.7

* github.com/go-testfixtures/testfixtures v3.5.0 -> v3.6.0

* github.com/issue9/identicon v1.0.1 -> v1.2.0

* github.com/klauspost/compress v1.11.8 -> v1.12.1

* github.com/mgechev/revive v1.0.3 -> v1.0.6

* github.com/microcosm-cc/bluemonday v1.0.7 -> v1.0.8

* github.com/niklasfasching/go-org v1.4.0 -> v1.5.0

* github.com/olivere/elastic v7.0.22 -> v7.0.24

* github.com/pelletier/go-toml v1.8.1 -> v1.9.0

* github.com/prometheus/client_golang v1.9.0 -> v1.10.0

* github.com/xanzy/go-gitlab v0.44.0 -> v0.48.0

* github.com/yuin/goldmark v1.3.3 -> v1.3.5

* github.com/6543/go-version v1.2.4 -> v1.3.1

* do github.com/lib/pq v1.10.0 -> v1.10.1 again ...
2021-04-22 20:08:53 -04:00

179 lines
4.3 KiB
Go
Vendored

package zstd
import (
"fmt"
"math/bits"
"github.com/klauspost/compress/zstd/internal/xxhash"
)
const (
dictShardBits = 6
)
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
lowMem bool
}
// 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 {
e.ensureHist(len(src))
} else {
if cap(e.hist) < int(e.maxMatchOff+maxCompressedBlockSize) {
panic(fmt.Errorf("unexpected buffer cap %d, want at least %d with window %d", cap(e.hist), e.maxMatchOff+maxCompressedBlockSize, e.maxMatchOff))
}
// 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
}
// ensureHist will ensure that history can keep at least this many bytes.
func (e *fastBase) ensureHist(n int) {
if cap(e.hist) >= n {
return
}
l := e.maxMatchOff
if (e.lowMem && e.maxMatchOff > maxCompressedBlockSize) || e.maxMatchOff <= maxCompressedBlockSize {
l += maxCompressedBlockSize
} else {
l += e.maxMatchOff
}
// Make it at least 1MB.
if l < 1<<20 && !e.lowMem {
l = 1 << 20
}
// Make it at least the requested size.
if l < int32(n) {
l = int32(n)
}
e.hist = make([]byte, 0, l)
}
// 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{lowMem: e.lowMem}
e.blk.init()
} else {
e.blk.reset(nil)
}
e.blk.initNewEncode()
if e.crc == nil {
e.crc = xxhash.New()
} else {
e.crc.Reset()
}
if d != nil {
low := e.lowMem
if singleBlock {
e.lowMem = true
}
e.ensureHist(d.DictContentSize() + maxCompressedBlockSize)
e.lowMem = low
}
// 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...)
}
}