mirror of
https://github.com/42wim/matterbridge.git
synced 2024-12-04 16:32:02 -08:00
1238 lines
34 KiB
Go
1238 lines
34 KiB
Go
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// Copyright 2019+ Klaus Post. All rights reserved.
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// License information can be found in the LICENSE file.
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// Based on work by Yann Collet, released under BSD License.
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package zstd
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import "fmt"
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const (
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betterLongTableBits = 19 // Bits used in the long match table
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betterLongTableSize = 1 << betterLongTableBits // Size of the table
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betterLongLen = 8 // Bytes used for table hash
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// Note: Increasing the short table bits or making the hash shorter
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// can actually lead to compression degradation since it will 'steal' more from the
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// long match table and match offsets are quite big.
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// This greatly depends on the type of input.
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betterShortTableBits = 13 // Bits used in the short match table
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betterShortTableSize = 1 << betterShortTableBits // Size of the table
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betterShortLen = 5 // Bytes used for table hash
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betterLongTableShardCnt = 1 << (betterLongTableBits - dictShardBits) // Number of shards in the table
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betterLongTableShardSize = betterLongTableSize / betterLongTableShardCnt // Size of an individual shard
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betterShortTableShardCnt = 1 << (betterShortTableBits - dictShardBits) // Number of shards in the table
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betterShortTableShardSize = betterShortTableSize / betterShortTableShardCnt // Size of an individual shard
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)
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type prevEntry struct {
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offset int32
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prev int32
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}
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// betterFastEncoder uses 2 tables, one for short matches (5 bytes) and one for long matches.
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// The long match table contains the previous entry with the same hash,
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// effectively making it a "chain" of length 2.
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// When we find a long match we choose between the two values and select the longest.
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// When we find a short match, after checking the long, we check if we can find a long at n+1
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// and that it is longer (lazy matching).
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type betterFastEncoder struct {
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fastBase
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table [betterShortTableSize]tableEntry
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longTable [betterLongTableSize]prevEntry
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}
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type betterFastEncoderDict struct {
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betterFastEncoder
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dictTable []tableEntry
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dictLongTable []prevEntry
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shortTableShardDirty [betterShortTableShardCnt]bool
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longTableShardDirty [betterLongTableShardCnt]bool
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allDirty bool
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}
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// Encode improves compression...
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func (e *betterFastEncoder) Encode(blk *blockEnc, src []byte) {
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const (
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// Input margin is the number of bytes we read (8)
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// and the maximum we will read ahead (2)
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inputMargin = 8 + 2
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minNonLiteralBlockSize = 16
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)
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// Protect against e.cur wraparound.
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for e.cur >= bufferReset {
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if len(e.hist) == 0 {
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for i := range e.table[:] {
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e.table[i] = tableEntry{}
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}
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for i := range e.longTable[:] {
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e.longTable[i] = prevEntry{}
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}
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e.cur = e.maxMatchOff
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break
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}
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// Shift down everything in the table that isn't already too far away.
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minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
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for i := range e.table[:] {
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v := e.table[i].offset
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if v < minOff {
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v = 0
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} else {
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v = v - e.cur + e.maxMatchOff
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}
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e.table[i].offset = v
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}
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for i := range e.longTable[:] {
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v := e.longTable[i].offset
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v2 := e.longTable[i].prev
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if v < minOff {
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v = 0
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v2 = 0
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} else {
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v = v - e.cur + e.maxMatchOff
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if v2 < minOff {
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v2 = 0
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} else {
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v2 = v2 - e.cur + e.maxMatchOff
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}
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}
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e.longTable[i] = prevEntry{
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offset: v,
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prev: v2,
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}
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}
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e.cur = e.maxMatchOff
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break
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}
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s := e.addBlock(src)
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blk.size = len(src)
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if len(src) < minNonLiteralBlockSize {
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blk.extraLits = len(src)
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blk.literals = blk.literals[:len(src)]
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copy(blk.literals, src)
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return
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}
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// Override src
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src = e.hist
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sLimit := int32(len(src)) - inputMargin
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// stepSize is the number of bytes to skip on every main loop iteration.
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// It should be >= 1.
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const stepSize = 1
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const kSearchStrength = 9
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// nextEmit is where in src the next emitLiteral should start from.
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nextEmit := s
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cv := load6432(src, s)
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// Relative offsets
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offset1 := int32(blk.recentOffsets[0])
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offset2 := int32(blk.recentOffsets[1])
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addLiterals := func(s *seq, until int32) {
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if until == nextEmit {
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return
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}
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blk.literals = append(blk.literals, src[nextEmit:until]...)
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s.litLen = uint32(until - nextEmit)
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}
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if debugEncoder {
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println("recent offsets:", blk.recentOffsets)
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}
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encodeLoop:
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for {
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var t int32
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// We allow the encoder to optionally turn off repeat offsets across blocks
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canRepeat := len(blk.sequences) > 2
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var matched int32
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for {
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if debugAsserts && canRepeat && offset1 == 0 {
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panic("offset0 was 0")
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}
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nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
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nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
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candidateL := e.longTable[nextHashL]
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candidateS := e.table[nextHashS]
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const repOff = 1
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repIndex := s - offset1 + repOff
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off := s + e.cur
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e.longTable[nextHashL] = prevEntry{offset: off, prev: candidateL.offset}
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e.table[nextHashS] = tableEntry{offset: off, val: uint32(cv)}
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if canRepeat {
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if repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>(repOff*8)) {
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// Consider history as well.
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var seq seq
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lenght := 4 + e.matchlen(s+4+repOff, repIndex+4, src)
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seq.matchLen = uint32(lenght - zstdMinMatch)
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// We might be able to match backwards.
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// Extend as long as we can.
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start := s + repOff
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// We end the search early, so we don't risk 0 literals
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// and have to do special offset treatment.
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startLimit := nextEmit + 1
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tMin := s - e.maxMatchOff
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if tMin < 0 {
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tMin = 0
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}
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for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
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repIndex--
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start--
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seq.matchLen++
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}
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addLiterals(&seq, start)
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// rep 0
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seq.offset = 1
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if debugSequences {
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println("repeat sequence", seq, "next s:", s)
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}
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blk.sequences = append(blk.sequences, seq)
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// Index match start+1 (long) -> s - 1
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index0 := s + repOff
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s += lenght + repOff
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nextEmit = s
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if s >= sLimit {
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if debugEncoder {
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println("repeat ended", s, lenght)
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}
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break encodeLoop
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}
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// Index skipped...
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for index0 < s-1 {
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cv0 := load6432(src, index0)
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cv1 := cv0 >> 8
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h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
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off := index0 + e.cur
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e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
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e.table[hashLen(cv1, betterShortTableBits, betterShortLen)] = tableEntry{offset: off + 1, val: uint32(cv1)}
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index0 += 2
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}
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cv = load6432(src, s)
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continue
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}
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const repOff2 = 1
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// We deviate from the reference encoder and also check offset 2.
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// Still slower and not much better, so disabled.
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// repIndex = s - offset2 + repOff2
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if false && repIndex >= 0 && load6432(src, repIndex) == load6432(src, s+repOff) {
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// Consider history as well.
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var seq seq
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lenght := 8 + e.matchlen(s+8+repOff2, repIndex+8, src)
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seq.matchLen = uint32(lenght - zstdMinMatch)
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// We might be able to match backwards.
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// Extend as long as we can.
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start := s + repOff2
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// We end the search early, so we don't risk 0 literals
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// and have to do special offset treatment.
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startLimit := nextEmit + 1
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tMin := s - e.maxMatchOff
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if tMin < 0 {
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tMin = 0
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}
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for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
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repIndex--
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start--
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seq.matchLen++
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}
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addLiterals(&seq, start)
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// rep 2
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seq.offset = 2
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if debugSequences {
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println("repeat sequence 2", seq, "next s:", s)
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}
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blk.sequences = append(blk.sequences, seq)
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index0 := s + repOff2
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s += lenght + repOff2
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nextEmit = s
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if s >= sLimit {
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if debugEncoder {
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println("repeat ended", s, lenght)
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}
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break encodeLoop
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}
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// Index skipped...
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for index0 < s-1 {
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cv0 := load6432(src, index0)
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cv1 := cv0 >> 8
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h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
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off := index0 + e.cur
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e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
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e.table[hashLen(cv1, betterShortTableBits, betterShortLen)] = tableEntry{offset: off + 1, val: uint32(cv1)}
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index0 += 2
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}
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cv = load6432(src, s)
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// Swap offsets
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offset1, offset2 = offset2, offset1
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continue
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}
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}
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// Find the offsets of our two matches.
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coffsetL := candidateL.offset - e.cur
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coffsetLP := candidateL.prev - e.cur
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// Check if we have a long match.
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if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
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// Found a long match, at least 8 bytes.
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matched = e.matchlen(s+8, coffsetL+8, src) + 8
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t = coffsetL
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if debugAsserts && s <= t {
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panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
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}
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if debugAsserts && s-t > e.maxMatchOff {
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panic("s - t >e.maxMatchOff")
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}
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if debugMatches {
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println("long match")
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}
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if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
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// Found a long match, at least 8 bytes.
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prevMatch := e.matchlen(s+8, coffsetLP+8, src) + 8
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if prevMatch > matched {
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matched = prevMatch
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t = coffsetLP
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}
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if debugAsserts && s <= t {
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panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
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}
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if debugAsserts && s-t > e.maxMatchOff {
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panic("s - t >e.maxMatchOff")
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}
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if debugMatches {
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println("long match")
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}
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}
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break
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}
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// Check if we have a long match on prev.
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if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
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// Found a long match, at least 8 bytes.
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matched = e.matchlen(s+8, coffsetLP+8, src) + 8
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t = coffsetLP
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if debugAsserts && s <= t {
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panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
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}
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if debugAsserts && s-t > e.maxMatchOff {
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panic("s - t >e.maxMatchOff")
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}
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if debugMatches {
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println("long match")
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}
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break
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}
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coffsetS := candidateS.offset - e.cur
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// Check if we have a short match.
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if s-coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
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// found a regular match
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matched = e.matchlen(s+4, coffsetS+4, src) + 4
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// See if we can find a long match at s+1
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const checkAt = 1
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cv := load6432(src, s+checkAt)
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nextHashL = hashLen(cv, betterLongTableBits, betterLongLen)
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candidateL = e.longTable[nextHashL]
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coffsetL = candidateL.offset - e.cur
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// We can store it, since we have at least a 4 byte match.
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e.longTable[nextHashL] = prevEntry{offset: s + checkAt + e.cur, prev: candidateL.offset}
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if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
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// Found a long match, at least 8 bytes.
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matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
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if matchedNext > matched {
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t = coffsetL
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s += checkAt
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matched = matchedNext
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if debugMatches {
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println("long match (after short)")
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}
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break
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}
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}
|
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||
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// Check prev long...
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coffsetL = candidateL.prev - e.cur
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if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
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// Found a long match, at least 8 bytes.
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matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
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if matchedNext > matched {
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t = coffsetL
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s += checkAt
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matched = matchedNext
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if debugMatches {
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println("prev long match (after short)")
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}
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break
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}
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}
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t = coffsetS
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if debugAsserts && s <= t {
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panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
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}
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if debugAsserts && s-t > e.maxMatchOff {
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panic("s - t >e.maxMatchOff")
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}
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if debugAsserts && t < 0 {
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panic("t<0")
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}
|
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if debugMatches {
|
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println("short match")
|
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}
|
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break
|
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}
|
||
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|
||
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// No match found, move forward in input.
|
||
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s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
|
||
|
if s >= sLimit {
|
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break encodeLoop
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}
|
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cv = load6432(src, s)
|
||
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}
|
||
|
|
||
|
// Try to find a better match by searching for a long match at the end of the current best match
|
||
|
if s+matched < sLimit {
|
||
|
nextHashL := hashLen(load6432(src, s+matched), betterLongTableBits, betterLongLen)
|
||
|
cv := load3232(src, s)
|
||
|
candidateL := e.longTable[nextHashL]
|
||
|
coffsetL := candidateL.offset - e.cur - matched
|
||
|
if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
|
||
|
// Found a long match, at least 4 bytes.
|
||
|
matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
|
||
|
if matchedNext > matched {
|
||
|
t = coffsetL
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matched = matchedNext
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if debugMatches {
|
||
|
println("long match at end-of-match")
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Check prev long...
|
||
|
if true {
|
||
|
coffsetL = candidateL.prev - e.cur - matched
|
||
|
if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
|
||
|
// Found a long match, at least 4 bytes.
|
||
|
matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
|
||
|
if matchedNext > matched {
|
||
|
t = coffsetL
|
||
|
matched = matchedNext
|
||
|
if debugMatches {
|
||
|
println("prev long match at end-of-match")
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
// A match has been found. Update recent offsets.
|
||
|
offset2 = offset1
|
||
|
offset1 = s - t
|
||
|
|
||
|
if debugAsserts && s <= t {
|
||
|
panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
|
||
|
}
|
||
|
|
||
|
if debugAsserts && canRepeat && int(offset1) > len(src) {
|
||
|
panic("invalid offset")
|
||
|
}
|
||
|
|
||
|
// Extend the n-byte match as long as possible.
|
||
|
l := matched
|
||
|
|
||
|
// Extend backwards
|
||
|
tMin := s - e.maxMatchOff
|
||
|
if tMin < 0 {
|
||
|
tMin = 0
|
||
|
}
|
||
|
for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
|
||
|
s--
|
||
|
t--
|
||
|
l++
|
||
|
}
|
||
|
|
||
|
// Write our sequence
|
||
|
var seq seq
|
||
|
seq.litLen = uint32(s - nextEmit)
|
||
|
seq.matchLen = uint32(l - zstdMinMatch)
|
||
|
if seq.litLen > 0 {
|
||
|
blk.literals = append(blk.literals, src[nextEmit:s]...)
|
||
|
}
|
||
|
seq.offset = uint32(s-t) + 3
|
||
|
s += l
|
||
|
if debugSequences {
|
||
|
println("sequence", seq, "next s:", s)
|
||
|
}
|
||
|
blk.sequences = append(blk.sequences, seq)
|
||
|
nextEmit = s
|
||
|
if s >= sLimit {
|
||
|
break encodeLoop
|
||
|
}
|
||
|
|
||
|
// Index match start+1 (long) -> s - 1
|
||
|
index0 := s - l + 1
|
||
|
for index0 < s-1 {
|
||
|
cv0 := load6432(src, index0)
|
||
|
cv1 := cv0 >> 8
|
||
|
h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
|
||
|
off := index0 + e.cur
|
||
|
e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
|
||
|
e.table[hashLen(cv1, betterShortTableBits, betterShortLen)] = tableEntry{offset: off + 1, val: uint32(cv1)}
|
||
|
index0 += 2
|
||
|
}
|
||
|
|
||
|
cv = load6432(src, s)
|
||
|
if !canRepeat {
|
||
|
continue
|
||
|
}
|
||
|
|
||
|
// Check offset 2
|
||
|
for {
|
||
|
o2 := s - offset2
|
||
|
if load3232(src, o2) != uint32(cv) {
|
||
|
// Do regular search
|
||
|
break
|
||
|
}
|
||
|
|
||
|
// Store this, since we have it.
|
||
|
nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
|
||
|
nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
|
||
|
|
||
|
// We have at least 4 byte match.
|
||
|
// No need to check backwards. We come straight from a match
|
||
|
l := 4 + e.matchlen(s+4, o2+4, src)
|
||
|
|
||
|
e.longTable[nextHashL] = prevEntry{offset: s + e.cur, prev: e.longTable[nextHashL].offset}
|
||
|
e.table[nextHashS] = tableEntry{offset: s + e.cur, val: uint32(cv)}
|
||
|
seq.matchLen = uint32(l) - zstdMinMatch
|
||
|
seq.litLen = 0
|
||
|
|
||
|
// Since litlen is always 0, this is offset 1.
|
||
|
seq.offset = 1
|
||
|
s += l
|
||
|
nextEmit = s
|
||
|
if debugSequences {
|
||
|
println("sequence", seq, "next s:", s)
|
||
|
}
|
||
|
blk.sequences = append(blk.sequences, seq)
|
||
|
|
||
|
// Swap offset 1 and 2.
|
||
|
offset1, offset2 = offset2, offset1
|
||
|
if s >= sLimit {
|
||
|
// Finished
|
||
|
break encodeLoop
|
||
|
}
|
||
|
cv = load6432(src, s)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
if int(nextEmit) < len(src) {
|
||
|
blk.literals = append(blk.literals, src[nextEmit:]...)
|
||
|
blk.extraLits = len(src) - int(nextEmit)
|
||
|
}
|
||
|
blk.recentOffsets[0] = uint32(offset1)
|
||
|
blk.recentOffsets[1] = uint32(offset2)
|
||
|
if debugEncoder {
|
||
|
println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// EncodeNoHist will encode a block with no history and no following blocks.
|
||
|
// Most notable difference is that src will not be copied for history and
|
||
|
// we do not need to check for max match length.
|
||
|
func (e *betterFastEncoder) EncodeNoHist(blk *blockEnc, src []byte) {
|
||
|
e.ensureHist(len(src))
|
||
|
e.Encode(blk, src)
|
||
|
}
|
||
|
|
||
|
// Encode improves compression...
|
||
|
func (e *betterFastEncoderDict) Encode(blk *blockEnc, src []byte) {
|
||
|
const (
|
||
|
// Input margin is the number of bytes we read (8)
|
||
|
// and the maximum we will read ahead (2)
|
||
|
inputMargin = 8 + 2
|
||
|
minNonLiteralBlockSize = 16
|
||
|
)
|
||
|
|
||
|
// Protect against e.cur wraparound.
|
||
|
for e.cur >= bufferReset {
|
||
|
if len(e.hist) == 0 {
|
||
|
for i := range e.table[:] {
|
||
|
e.table[i] = tableEntry{}
|
||
|
}
|
||
|
for i := range e.longTable[:] {
|
||
|
e.longTable[i] = prevEntry{}
|
||
|
}
|
||
|
e.cur = e.maxMatchOff
|
||
|
e.allDirty = true
|
||
|
break
|
||
|
}
|
||
|
// Shift down everything in the table that isn't already too far away.
|
||
|
minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
|
||
|
for i := range e.table[:] {
|
||
|
v := e.table[i].offset
|
||
|
if v < minOff {
|
||
|
v = 0
|
||
|
} else {
|
||
|
v = v - e.cur + e.maxMatchOff
|
||
|
}
|
||
|
e.table[i].offset = v
|
||
|
}
|
||
|
for i := range e.longTable[:] {
|
||
|
v := e.longTable[i].offset
|
||
|
v2 := e.longTable[i].prev
|
||
|
if v < minOff {
|
||
|
v = 0
|
||
|
v2 = 0
|
||
|
} else {
|
||
|
v = v - e.cur + e.maxMatchOff
|
||
|
if v2 < minOff {
|
||
|
v2 = 0
|
||
|
} else {
|
||
|
v2 = v2 - e.cur + e.maxMatchOff
|
||
|
}
|
||
|
}
|
||
|
e.longTable[i] = prevEntry{
|
||
|
offset: v,
|
||
|
prev: v2,
|
||
|
}
|
||
|
}
|
||
|
e.allDirty = true
|
||
|
e.cur = e.maxMatchOff
|
||
|
break
|
||
|
}
|
||
|
|
||
|
s := e.addBlock(src)
|
||
|
blk.size = len(src)
|
||
|
if len(src) < minNonLiteralBlockSize {
|
||
|
blk.extraLits = len(src)
|
||
|
blk.literals = blk.literals[:len(src)]
|
||
|
copy(blk.literals, src)
|
||
|
return
|
||
|
}
|
||
|
|
||
|
// Override src
|
||
|
src = e.hist
|
||
|
sLimit := int32(len(src)) - inputMargin
|
||
|
// stepSize is the number of bytes to skip on every main loop iteration.
|
||
|
// It should be >= 1.
|
||
|
const stepSize = 1
|
||
|
|
||
|
const kSearchStrength = 9
|
||
|
|
||
|
// nextEmit is where in src the next emitLiteral should start from.
|
||
|
nextEmit := s
|
||
|
cv := load6432(src, s)
|
||
|
|
||
|
// Relative offsets
|
||
|
offset1 := int32(blk.recentOffsets[0])
|
||
|
offset2 := int32(blk.recentOffsets[1])
|
||
|
|
||
|
addLiterals := func(s *seq, until int32) {
|
||
|
if until == nextEmit {
|
||
|
return
|
||
|
}
|
||
|
blk.literals = append(blk.literals, src[nextEmit:until]...)
|
||
|
s.litLen = uint32(until - nextEmit)
|
||
|
}
|
||
|
if debugEncoder {
|
||
|
println("recent offsets:", blk.recentOffsets)
|
||
|
}
|
||
|
|
||
|
encodeLoop:
|
||
|
for {
|
||
|
var t int32
|
||
|
// We allow the encoder to optionally turn off repeat offsets across blocks
|
||
|
canRepeat := len(blk.sequences) > 2
|
||
|
var matched int32
|
||
|
|
||
|
for {
|
||
|
if debugAsserts && canRepeat && offset1 == 0 {
|
||
|
panic("offset0 was 0")
|
||
|
}
|
||
|
|
||
|
nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
|
||
|
nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
|
||
|
candidateL := e.longTable[nextHashL]
|
||
|
candidateS := e.table[nextHashS]
|
||
|
|
||
|
const repOff = 1
|
||
|
repIndex := s - offset1 + repOff
|
||
|
off := s + e.cur
|
||
|
e.longTable[nextHashL] = prevEntry{offset: off, prev: candidateL.offset}
|
||
|
e.markLongShardDirty(nextHashL)
|
||
|
e.table[nextHashS] = tableEntry{offset: off, val: uint32(cv)}
|
||
|
e.markShortShardDirty(nextHashS)
|
||
|
|
||
|
if canRepeat {
|
||
|
if repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>(repOff*8)) {
|
||
|
// Consider history as well.
|
||
|
var seq seq
|
||
|
lenght := 4 + e.matchlen(s+4+repOff, repIndex+4, src)
|
||
|
|
||
|
seq.matchLen = uint32(lenght - zstdMinMatch)
|
||
|
|
||
|
// We might be able to match backwards.
|
||
|
// Extend as long as we can.
|
||
|
start := s + repOff
|
||
|
// We end the search early, so we don't risk 0 literals
|
||
|
// and have to do special offset treatment.
|
||
|
startLimit := nextEmit + 1
|
||
|
|
||
|
tMin := s - e.maxMatchOff
|
||
|
if tMin < 0 {
|
||
|
tMin = 0
|
||
|
}
|
||
|
for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
|
||
|
repIndex--
|
||
|
start--
|
||
|
seq.matchLen++
|
||
|
}
|
||
|
addLiterals(&seq, start)
|
||
|
|
||
|
// rep 0
|
||
|
seq.offset = 1
|
||
|
if debugSequences {
|
||
|
println("repeat sequence", seq, "next s:", s)
|
||
|
}
|
||
|
blk.sequences = append(blk.sequences, seq)
|
||
|
|
||
|
// Index match start+1 (long) -> s - 1
|
||
|
index0 := s + repOff
|
||
|
s += lenght + repOff
|
||
|
|
||
|
nextEmit = s
|
||
|
if s >= sLimit {
|
||
|
if debugEncoder {
|
||
|
println("repeat ended", s, lenght)
|
||
|
|
||
|
}
|
||
|
break encodeLoop
|
||
|
}
|
||
|
// Index skipped...
|
||
|
for index0 < s-1 {
|
||
|
cv0 := load6432(src, index0)
|
||
|
cv1 := cv0 >> 8
|
||
|
h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
|
||
|
off := index0 + e.cur
|
||
|
e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
|
||
|
e.markLongShardDirty(h0)
|
||
|
h1 := hashLen(cv1, betterShortTableBits, betterShortLen)
|
||
|
e.table[h1] = tableEntry{offset: off + 1, val: uint32(cv1)}
|
||
|
e.markShortShardDirty(h1)
|
||
|
index0 += 2
|
||
|
}
|
||
|
cv = load6432(src, s)
|
||
|
continue
|
||
|
}
|
||
|
const repOff2 = 1
|
||
|
|
||
|
// We deviate from the reference encoder and also check offset 2.
|
||
|
// Still slower and not much better, so disabled.
|
||
|
// repIndex = s - offset2 + repOff2
|
||
|
if false && repIndex >= 0 && load6432(src, repIndex) == load6432(src, s+repOff) {
|
||
|
// Consider history as well.
|
||
|
var seq seq
|
||
|
lenght := 8 + e.matchlen(s+8+repOff2, repIndex+8, src)
|
||
|
|
||
|
seq.matchLen = uint32(lenght - zstdMinMatch)
|
||
|
|
||
|
// We might be able to match backwards.
|
||
|
// Extend as long as we can.
|
||
|
start := s + repOff2
|
||
|
// We end the search early, so we don't risk 0 literals
|
||
|
// and have to do special offset treatment.
|
||
|
startLimit := nextEmit + 1
|
||
|
|
||
|
tMin := s - e.maxMatchOff
|
||
|
if tMin < 0 {
|
||
|
tMin = 0
|
||
|
}
|
||
|
for repIndex > tMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch-1 {
|
||
|
repIndex--
|
||
|
start--
|
||
|
seq.matchLen++
|
||
|
}
|
||
|
addLiterals(&seq, start)
|
||
|
|
||
|
// rep 2
|
||
|
seq.offset = 2
|
||
|
if debugSequences {
|
||
|
println("repeat sequence 2", seq, "next s:", s)
|
||
|
}
|
||
|
blk.sequences = append(blk.sequences, seq)
|
||
|
|
||
|
index0 := s + repOff2
|
||
|
s += lenght + repOff2
|
||
|
nextEmit = s
|
||
|
if s >= sLimit {
|
||
|
if debugEncoder {
|
||
|
println("repeat ended", s, lenght)
|
||
|
|
||
|
}
|
||
|
break encodeLoop
|
||
|
}
|
||
|
|
||
|
// Index skipped...
|
||
|
for index0 < s-1 {
|
||
|
cv0 := load6432(src, index0)
|
||
|
cv1 := cv0 >> 8
|
||
|
h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
|
||
|
off := index0 + e.cur
|
||
|
e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
|
||
|
e.markLongShardDirty(h0)
|
||
|
h1 := hashLen(cv1, betterShortTableBits, betterShortLen)
|
||
|
e.table[h1] = tableEntry{offset: off + 1, val: uint32(cv1)}
|
||
|
e.markShortShardDirty(h1)
|
||
|
index0 += 2
|
||
|
}
|
||
|
cv = load6432(src, s)
|
||
|
// Swap offsets
|
||
|
offset1, offset2 = offset2, offset1
|
||
|
continue
|
||
|
}
|
||
|
}
|
||
|
// Find the offsets of our two matches.
|
||
|
coffsetL := candidateL.offset - e.cur
|
||
|
coffsetLP := candidateL.prev - e.cur
|
||
|
|
||
|
// Check if we have a long match.
|
||
|
if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
|
||
|
// Found a long match, at least 8 bytes.
|
||
|
matched = e.matchlen(s+8, coffsetL+8, src) + 8
|
||
|
t = coffsetL
|
||
|
if debugAsserts && s <= t {
|
||
|
panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
|
||
|
}
|
||
|
if debugAsserts && s-t > e.maxMatchOff {
|
||
|
panic("s - t >e.maxMatchOff")
|
||
|
}
|
||
|
if debugMatches {
|
||
|
println("long match")
|
||
|
}
|
||
|
|
||
|
if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
|
||
|
// Found a long match, at least 8 bytes.
|
||
|
prevMatch := e.matchlen(s+8, coffsetLP+8, src) + 8
|
||
|
if prevMatch > matched {
|
||
|
matched = prevMatch
|
||
|
t = coffsetLP
|
||
|
}
|
||
|
if debugAsserts && s <= t {
|
||
|
panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
|
||
|
}
|
||
|
if debugAsserts && s-t > e.maxMatchOff {
|
||
|
panic("s - t >e.maxMatchOff")
|
||
|
}
|
||
|
if debugMatches {
|
||
|
println("long match")
|
||
|
}
|
||
|
}
|
||
|
break
|
||
|
}
|
||
|
|
||
|
// Check if we have a long match on prev.
|
||
|
if s-coffsetLP < e.maxMatchOff && cv == load6432(src, coffsetLP) {
|
||
|
// Found a long match, at least 8 bytes.
|
||
|
matched = e.matchlen(s+8, coffsetLP+8, src) + 8
|
||
|
t = coffsetLP
|
||
|
if debugAsserts && s <= t {
|
||
|
panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
|
||
|
}
|
||
|
if debugAsserts && s-t > e.maxMatchOff {
|
||
|
panic("s - t >e.maxMatchOff")
|
||
|
}
|
||
|
if debugMatches {
|
||
|
println("long match")
|
||
|
}
|
||
|
break
|
||
|
}
|
||
|
|
||
|
coffsetS := candidateS.offset - e.cur
|
||
|
|
||
|
// Check if we have a short match.
|
||
|
if s-coffsetS < e.maxMatchOff && uint32(cv) == candidateS.val {
|
||
|
// found a regular match
|
||
|
matched = e.matchlen(s+4, coffsetS+4, src) + 4
|
||
|
|
||
|
// See if we can find a long match at s+1
|
||
|
const checkAt = 1
|
||
|
cv := load6432(src, s+checkAt)
|
||
|
nextHashL = hashLen(cv, betterLongTableBits, betterLongLen)
|
||
|
candidateL = e.longTable[nextHashL]
|
||
|
coffsetL = candidateL.offset - e.cur
|
||
|
|
||
|
// We can store it, since we have at least a 4 byte match.
|
||
|
e.longTable[nextHashL] = prevEntry{offset: s + checkAt + e.cur, prev: candidateL.offset}
|
||
|
e.markLongShardDirty(nextHashL)
|
||
|
if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
|
||
|
// Found a long match, at least 8 bytes.
|
||
|
matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
|
||
|
if matchedNext > matched {
|
||
|
t = coffsetL
|
||
|
s += checkAt
|
||
|
matched = matchedNext
|
||
|
if debugMatches {
|
||
|
println("long match (after short)")
|
||
|
}
|
||
|
break
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Check prev long...
|
||
|
coffsetL = candidateL.prev - e.cur
|
||
|
if s-coffsetL < e.maxMatchOff && cv == load6432(src, coffsetL) {
|
||
|
// Found a long match, at least 8 bytes.
|
||
|
matchedNext := e.matchlen(s+8+checkAt, coffsetL+8, src) + 8
|
||
|
if matchedNext > matched {
|
||
|
t = coffsetL
|
||
|
s += checkAt
|
||
|
matched = matchedNext
|
||
|
if debugMatches {
|
||
|
println("prev long match (after short)")
|
||
|
}
|
||
|
break
|
||
|
}
|
||
|
}
|
||
|
t = coffsetS
|
||
|
if debugAsserts && s <= t {
|
||
|
panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
|
||
|
}
|
||
|
if debugAsserts && s-t > e.maxMatchOff {
|
||
|
panic("s - t >e.maxMatchOff")
|
||
|
}
|
||
|
if debugAsserts && t < 0 {
|
||
|
panic("t<0")
|
||
|
}
|
||
|
if debugMatches {
|
||
|
println("short match")
|
||
|
}
|
||
|
break
|
||
|
}
|
||
|
|
||
|
// No match found, move forward in input.
|
||
|
s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
|
||
|
if s >= sLimit {
|
||
|
break encodeLoop
|
||
|
}
|
||
|
cv = load6432(src, s)
|
||
|
}
|
||
|
// Try to find a better match by searching for a long match at the end of the current best match
|
||
|
if s+matched < sLimit {
|
||
|
nextHashL := hashLen(load6432(src, s+matched), betterLongTableBits, betterLongLen)
|
||
|
cv := load3232(src, s)
|
||
|
candidateL := e.longTable[nextHashL]
|
||
|
coffsetL := candidateL.offset - e.cur - matched
|
||
|
if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
|
||
|
// Found a long match, at least 4 bytes.
|
||
|
matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
|
||
|
if matchedNext > matched {
|
||
|
t = coffsetL
|
||
|
matched = matchedNext
|
||
|
if debugMatches {
|
||
|
println("long match at end-of-match")
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// Check prev long...
|
||
|
if true {
|
||
|
coffsetL = candidateL.prev - e.cur - matched
|
||
|
if coffsetL >= 0 && coffsetL < s && s-coffsetL < e.maxMatchOff && cv == load3232(src, coffsetL) {
|
||
|
// Found a long match, at least 4 bytes.
|
||
|
matchedNext := e.matchlen(s+4, coffsetL+4, src) + 4
|
||
|
if matchedNext > matched {
|
||
|
t = coffsetL
|
||
|
matched = matchedNext
|
||
|
if debugMatches {
|
||
|
println("prev long match at end-of-match")
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
// A match has been found. Update recent offsets.
|
||
|
offset2 = offset1
|
||
|
offset1 = s - t
|
||
|
|
||
|
if debugAsserts && s <= t {
|
||
|
panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
|
||
|
}
|
||
|
|
||
|
if debugAsserts && canRepeat && int(offset1) > len(src) {
|
||
|
panic("invalid offset")
|
||
|
}
|
||
|
|
||
|
// Extend the n-byte match as long as possible.
|
||
|
l := matched
|
||
|
|
||
|
// Extend backwards
|
||
|
tMin := s - e.maxMatchOff
|
||
|
if tMin < 0 {
|
||
|
tMin = 0
|
||
|
}
|
||
|
for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
|
||
|
s--
|
||
|
t--
|
||
|
l++
|
||
|
}
|
||
|
|
||
|
// Write our sequence
|
||
|
var seq seq
|
||
|
seq.litLen = uint32(s - nextEmit)
|
||
|
seq.matchLen = uint32(l - zstdMinMatch)
|
||
|
if seq.litLen > 0 {
|
||
|
blk.literals = append(blk.literals, src[nextEmit:s]...)
|
||
|
}
|
||
|
seq.offset = uint32(s-t) + 3
|
||
|
s += l
|
||
|
if debugSequences {
|
||
|
println("sequence", seq, "next s:", s)
|
||
|
}
|
||
|
blk.sequences = append(blk.sequences, seq)
|
||
|
nextEmit = s
|
||
|
if s >= sLimit {
|
||
|
break encodeLoop
|
||
|
}
|
||
|
|
||
|
// Index match start+1 (long) -> s - 1
|
||
|
index0 := s - l + 1
|
||
|
for index0 < s-1 {
|
||
|
cv0 := load6432(src, index0)
|
||
|
cv1 := cv0 >> 8
|
||
|
h0 := hashLen(cv0, betterLongTableBits, betterLongLen)
|
||
|
off := index0 + e.cur
|
||
|
e.longTable[h0] = prevEntry{offset: off, prev: e.longTable[h0].offset}
|
||
|
e.markLongShardDirty(h0)
|
||
|
h1 := hashLen(cv1, betterShortTableBits, betterShortLen)
|
||
|
e.table[h1] = tableEntry{offset: off + 1, val: uint32(cv1)}
|
||
|
e.markShortShardDirty(h1)
|
||
|
index0 += 2
|
||
|
}
|
||
|
|
||
|
cv = load6432(src, s)
|
||
|
if !canRepeat {
|
||
|
continue
|
||
|
}
|
||
|
|
||
|
// Check offset 2
|
||
|
for {
|
||
|
o2 := s - offset2
|
||
|
if load3232(src, o2) != uint32(cv) {
|
||
|
// Do regular search
|
||
|
break
|
||
|
}
|
||
|
|
||
|
// Store this, since we have it.
|
||
|
nextHashS := hashLen(cv, betterShortTableBits, betterShortLen)
|
||
|
nextHashL := hashLen(cv, betterLongTableBits, betterLongLen)
|
||
|
|
||
|
// We have at least 4 byte match.
|
||
|
// No need to check backwards. We come straight from a match
|
||
|
l := 4 + e.matchlen(s+4, o2+4, src)
|
||
|
|
||
|
e.longTable[nextHashL] = prevEntry{offset: s + e.cur, prev: e.longTable[nextHashL].offset}
|
||
|
e.markLongShardDirty(nextHashL)
|
||
|
e.table[nextHashS] = tableEntry{offset: s + e.cur, val: uint32(cv)}
|
||
|
e.markShortShardDirty(nextHashS)
|
||
|
seq.matchLen = uint32(l) - zstdMinMatch
|
||
|
seq.litLen = 0
|
||
|
|
||
|
// Since litlen is always 0, this is offset 1.
|
||
|
seq.offset = 1
|
||
|
s += l
|
||
|
nextEmit = s
|
||
|
if debugSequences {
|
||
|
println("sequence", seq, "next s:", s)
|
||
|
}
|
||
|
blk.sequences = append(blk.sequences, seq)
|
||
|
|
||
|
// Swap offset 1 and 2.
|
||
|
offset1, offset2 = offset2, offset1
|
||
|
if s >= sLimit {
|
||
|
// Finished
|
||
|
break encodeLoop
|
||
|
}
|
||
|
cv = load6432(src, s)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
if int(nextEmit) < len(src) {
|
||
|
blk.literals = append(blk.literals, src[nextEmit:]...)
|
||
|
blk.extraLits = len(src) - int(nextEmit)
|
||
|
}
|
||
|
blk.recentOffsets[0] = uint32(offset1)
|
||
|
blk.recentOffsets[1] = uint32(offset2)
|
||
|
if debugEncoder {
|
||
|
println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// ResetDict will reset and set a dictionary if not nil
|
||
|
func (e *betterFastEncoder) Reset(d *dict, singleBlock bool) {
|
||
|
e.resetBase(d, singleBlock)
|
||
|
if d != nil {
|
||
|
panic("betterFastEncoder: Reset with dict")
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// ResetDict will reset and set a dictionary if not nil
|
||
|
func (e *betterFastEncoderDict) Reset(d *dict, singleBlock bool) {
|
||
|
e.resetBase(d, singleBlock)
|
||
|
if d == nil {
|
||
|
return
|
||
|
}
|
||
|
// Init or copy dict table
|
||
|
if len(e.dictTable) != len(e.table) || d.id != e.lastDictID {
|
||
|
if len(e.dictTable) != len(e.table) {
|
||
|
e.dictTable = make([]tableEntry, len(e.table))
|
||
|
}
|
||
|
end := int32(len(d.content)) - 8 + e.maxMatchOff
|
||
|
for i := e.maxMatchOff; i < end; i += 4 {
|
||
|
const hashLog = betterShortTableBits
|
||
|
|
||
|
cv := load6432(d.content, i-e.maxMatchOff)
|
||
|
nextHash := hashLen(cv, hashLog, betterShortLen) // 0 -> 4
|
||
|
nextHash1 := hashLen(cv>>8, hashLog, betterShortLen) // 1 -> 5
|
||
|
nextHash2 := hashLen(cv>>16, hashLog, betterShortLen) // 2 -> 6
|
||
|
nextHash3 := hashLen(cv>>24, hashLog, betterShortLen) // 3 -> 7
|
||
|
e.dictTable[nextHash] = tableEntry{
|
||
|
val: uint32(cv),
|
||
|
offset: i,
|
||
|
}
|
||
|
e.dictTable[nextHash1] = tableEntry{
|
||
|
val: uint32(cv >> 8),
|
||
|
offset: i + 1,
|
||
|
}
|
||
|
e.dictTable[nextHash2] = tableEntry{
|
||
|
val: uint32(cv >> 16),
|
||
|
offset: i + 2,
|
||
|
}
|
||
|
e.dictTable[nextHash3] = tableEntry{
|
||
|
val: uint32(cv >> 24),
|
||
|
offset: i + 3,
|
||
|
}
|
||
|
}
|
||
|
e.lastDictID = d.id
|
||
|
e.allDirty = true
|
||
|
}
|
||
|
|
||
|
// Init or copy dict table
|
||
|
if len(e.dictLongTable) != len(e.longTable) || d.id != e.lastDictID {
|
||
|
if len(e.dictLongTable) != len(e.longTable) {
|
||
|
e.dictLongTable = make([]prevEntry, len(e.longTable))
|
||
|
}
|
||
|
if len(d.content) >= 8 {
|
||
|
cv := load6432(d.content, 0)
|
||
|
h := hashLen(cv, betterLongTableBits, betterLongLen)
|
||
|
e.dictLongTable[h] = prevEntry{
|
||
|
offset: e.maxMatchOff,
|
||
|
prev: e.dictLongTable[h].offset,
|
||
|
}
|
||
|
|
||
|
end := int32(len(d.content)) - 8 + e.maxMatchOff
|
||
|
off := 8 // First to read
|
||
|
for i := e.maxMatchOff + 1; i < end; i++ {
|
||
|
cv = cv>>8 | (uint64(d.content[off]) << 56)
|
||
|
h := hashLen(cv, betterLongTableBits, betterLongLen)
|
||
|
e.dictLongTable[h] = prevEntry{
|
||
|
offset: i,
|
||
|
prev: e.dictLongTable[h].offset,
|
||
|
}
|
||
|
off++
|
||
|
}
|
||
|
}
|
||
|
e.lastDictID = d.id
|
||
|
e.allDirty = true
|
||
|
}
|
||
|
|
||
|
// Reset table to initial state
|
||
|
{
|
||
|
dirtyShardCnt := 0
|
||
|
if !e.allDirty {
|
||
|
for i := range e.shortTableShardDirty {
|
||
|
if e.shortTableShardDirty[i] {
|
||
|
dirtyShardCnt++
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
const shardCnt = betterShortTableShardCnt
|
||
|
const shardSize = betterShortTableShardSize
|
||
|
if e.allDirty || dirtyShardCnt > shardCnt*4/6 {
|
||
|
copy(e.table[:], e.dictTable)
|
||
|
for i := range e.shortTableShardDirty {
|
||
|
e.shortTableShardDirty[i] = false
|
||
|
}
|
||
|
} else {
|
||
|
for i := range e.shortTableShardDirty {
|
||
|
if !e.shortTableShardDirty[i] {
|
||
|
continue
|
||
|
}
|
||
|
|
||
|
copy(e.table[i*shardSize:(i+1)*shardSize], e.dictTable[i*shardSize:(i+1)*shardSize])
|
||
|
e.shortTableShardDirty[i] = false
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
{
|
||
|
dirtyShardCnt := 0
|
||
|
if !e.allDirty {
|
||
|
for i := range e.shortTableShardDirty {
|
||
|
if e.shortTableShardDirty[i] {
|
||
|
dirtyShardCnt++
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
const shardCnt = betterLongTableShardCnt
|
||
|
const shardSize = betterLongTableShardSize
|
||
|
if e.allDirty || dirtyShardCnt > shardCnt*4/6 {
|
||
|
copy(e.longTable[:], e.dictLongTable)
|
||
|
for i := range e.longTableShardDirty {
|
||
|
e.longTableShardDirty[i] = false
|
||
|
}
|
||
|
} else {
|
||
|
for i := range e.longTableShardDirty {
|
||
|
if !e.longTableShardDirty[i] {
|
||
|
continue
|
||
|
}
|
||
|
|
||
|
copy(e.longTable[i*shardSize:(i+1)*shardSize], e.dictLongTable[i*shardSize:(i+1)*shardSize])
|
||
|
e.longTableShardDirty[i] = false
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
e.cur = e.maxMatchOff
|
||
|
e.allDirty = false
|
||
|
}
|
||
|
|
||
|
func (e *betterFastEncoderDict) markLongShardDirty(entryNum uint32) {
|
||
|
e.longTableShardDirty[entryNum/betterLongTableShardSize] = true
|
||
|
}
|
||
|
|
||
|
func (e *betterFastEncoderDict) markShortShardDirty(entryNum uint32) {
|
||
|
e.shortTableShardDirty[entryNum/betterShortTableShardSize] = true
|
||
|
}
|