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			662 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Go
		
	
	
	
		
			Vendored
		
	
	
	
			
		
		
	
	
			662 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Go
		
	
	
	
		
			Vendored
		
	
	
	
| // Copyright 2019+ Klaus Post. All rights reserved.
 | |
| // License information can be found in the LICENSE file.
 | |
| // Based on work by Yann Collet, released under BSD License.
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| 
 | |
| package zstd
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| 
 | |
| import (
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| 	"fmt"
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| 	"math"
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| 	"math/bits"
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| )
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| 
 | |
| const (
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| 	tableBits      = 15             // Bits used in the table
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| 	tableSize      = 1 << tableBits // Size of the table
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| 	tableMask      = tableSize - 1  // Mask for table indices. Redundant, but can eliminate bounds checks.
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| 	maxMatchLength = 131074
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| )
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| 
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| type tableEntry struct {
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| 	val    uint32
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| 	offset int32
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| }
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| 
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| type fastEncoder struct {
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| 	fastBase
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| 	table     [tableSize]tableEntry
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| 	dictTable []tableEntry
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| }
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| 
 | |
| // Encode mimmics functionality in zstd_fast.c
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| func (e *fastEncoder) Encode(blk *blockEnc, src []byte) {
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| 	const (
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| 		inputMargin            = 8
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| 		minNonLiteralBlockSize = 1 + 1 + inputMargin
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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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| 			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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| 		e.cur = e.maxMatchOff
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| 		break
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| 	}
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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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| 
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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 >= 2.
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| 	const stepSize = 2
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| 
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| 	// TEMPLATE
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| 	const hashLog = tableBits
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| 	// seems global, but would be nice to tweak.
 | |
| 	const kSearchStrength = 7
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| 
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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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| 
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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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| 
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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 debug {
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| 		println("recent offsets:", blk.recentOffsets)
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| 	}
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| 
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| encodeLoop:
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| 	for {
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| 		// t will contain the match offset when we find one.
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| 		// When existing the search loop, we have already checked 4 bytes.
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| 		var t int32
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| 
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| 		// We will not use repeat offsets across blocks.
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| 		// By not using them for the first 3 matches
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| 		canRepeat := len(blk.sequences) > 2
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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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| 
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| 			nextHash := hash6(cv, hashLog)
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| 			nextHash2 := hash6(cv>>8, hashLog)
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| 			candidate := e.table[nextHash]
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| 			candidate2 := e.table[nextHash2]
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| 			repIndex := s - offset1 + 2
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| 
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| 			e.table[nextHash] = tableEntry{offset: s + e.cur, val: uint32(cv)}
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| 			e.table[nextHash2] = tableEntry{offset: s + e.cur + 1, val: uint32(cv >> 8)}
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| 
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| 			if canRepeat && repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>16) {
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| 				// Consider history as well.
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| 				var seq seq
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| 				var length int32
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| 				// length = 4 + e.matchlen(s+6, repIndex+4, src)
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| 				{
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| 					a := src[s+6:]
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| 					b := src[repIndex+4:]
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| 					endI := len(a) & (math.MaxInt32 - 7)
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| 					length = int32(endI) + 4
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| 					for i := 0; i < endI; i += 8 {
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| 						if diff := load64(a, i) ^ load64(b, i); diff != 0 {
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| 							length = int32(i+bits.TrailingZeros64(diff)>>3) + 4
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| 							break
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| 						}
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| 					}
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| 				}
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| 
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| 				seq.matchLen = uint32(length - zstdMinMatch)
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| 
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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 + 2
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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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| 
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| 				sMin := s - e.maxMatchOff
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| 				if sMin < 0 {
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| 					sMin = 0
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| 				}
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| 				for repIndex > sMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch {
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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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| 
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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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| 				s += length + 2
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| 				nextEmit = s
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| 				if s >= sLimit {
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| 					if debug {
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| 						println("repeat ended", s, length)
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| 
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| 					}
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| 					break encodeLoop
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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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| 			coffset0 := s - (candidate.offset - e.cur)
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| 			coffset1 := s - (candidate2.offset - e.cur) + 1
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| 			if coffset0 < e.maxMatchOff && uint32(cv) == candidate.val {
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| 				// found a regular match
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| 				t = candidate.offset - e.cur
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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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| 				break
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| 			}
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| 
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| 			if coffset1 < e.maxMatchOff && uint32(cv>>8) == candidate2.val {
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| 				// found a regular match
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| 				t = candidate2.offset - e.cur
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| 				s++
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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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| 				break
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| 			}
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| 			s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
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| 			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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| 		}
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| 		// A 4-byte match has been found. We'll later see if more than 4 bytes.
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| 		offset2 = offset1
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| 		offset1 = s - t
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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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| 
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| 		if debugAsserts && canRepeat && int(offset1) > len(src) {
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| 			panic("invalid offset")
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| 		}
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| 
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| 		// Extend the 4-byte match as long as possible.
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| 		//l := e.matchlen(s+4, t+4, src) + 4
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| 		var l int32
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| 		{
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| 			a := src[s+4:]
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| 			b := src[t+4:]
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| 			endI := len(a) & (math.MaxInt32 - 7)
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| 			l = int32(endI) + 4
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| 			for i := 0; i < endI; i += 8 {
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| 				if diff := load64(a, i) ^ load64(b, i); diff != 0 {
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| 					l = int32(i+bits.TrailingZeros64(diff)>>3) + 4
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| 					break
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| 				}
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| 			}
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| 		}
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| 
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| 		// Extend backwards
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| 		tMin := s - e.maxMatchOff
 | |
| 		if tMin < 0 {
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| 			tMin = 0
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| 		}
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| 		for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
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| 			s--
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| 			t--
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| 			l++
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| 		}
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| 
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| 		// Write our sequence.
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| 		var seq seq
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| 		seq.litLen = uint32(s - nextEmit)
 | |
| 		seq.matchLen = uint32(l - zstdMinMatch)
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| 		if seq.litLen > 0 {
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| 			blk.literals = append(blk.literals, src[nextEmit:s]...)
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| 		}
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| 		// Don't use repeat offsets
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| 		seq.offset = uint32(s-t) + 3
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| 		s += l
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| 		if debugSequences {
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| 			println("sequence", seq, "next s:", s)
 | |
| 		}
 | |
| 		blk.sequences = append(blk.sequences, seq)
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| 		nextEmit = s
 | |
| 		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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| 
 | |
| 		// Check offset 2
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| 		if o2 := s - offset2; canRepeat && load3232(src, o2) == uint32(cv) {
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| 			// We have at least 4 byte match.
 | |
| 			// No need to check backwards. We come straight from a match
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| 			//l := 4 + e.matchlen(s+4, o2+4, src)
 | |
| 			var l int32
 | |
| 			{
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| 				a := src[s+4:]
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| 				b := src[o2+4:]
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| 				endI := len(a) & (math.MaxInt32 - 7)
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| 				l = int32(endI) + 4
 | |
| 				for i := 0; i < endI; i += 8 {
 | |
| 					if diff := load64(a, i) ^ load64(b, i); diff != 0 {
 | |
| 						l = int32(i+bits.TrailingZeros64(diff)>>3) + 4
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| 						break
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| 					}
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| 				}
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| 			}
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| 
 | |
| 			// Store this, since we have it.
 | |
| 			nextHash := hash6(cv, hashLog)
 | |
| 			e.table[nextHash] = 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 {
 | |
| 				break encodeLoop
 | |
| 			}
 | |
| 			// Prepare next loop.
 | |
| 			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 debug {
 | |
| 		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 *fastEncoder) EncodeNoHist(blk *blockEnc, src []byte) {
 | |
| 	const (
 | |
| 		inputMargin            = 8
 | |
| 		minNonLiteralBlockSize = 1 + 1 + inputMargin
 | |
| 	)
 | |
| 	if debug {
 | |
| 		if len(src) > maxBlockSize {
 | |
| 			panic("src too big")
 | |
| 		}
 | |
| 	}
 | |
| 
 | |
| 	// Protect against e.cur wraparound.
 | |
| 	if e.cur >= bufferReset {
 | |
| 		for i := range e.table[:] {
 | |
| 			e.table[i] = tableEntry{}
 | |
| 		}
 | |
| 		e.cur = e.maxMatchOff
 | |
| 	}
 | |
| 
 | |
| 	s := int32(0)
 | |
| 	blk.size = len(src)
 | |
| 	if len(src) < minNonLiteralBlockSize {
 | |
| 		blk.extraLits = len(src)
 | |
| 		blk.literals = blk.literals[:len(src)]
 | |
| 		copy(blk.literals, src)
 | |
| 		return
 | |
| 	}
 | |
| 
 | |
| 	sLimit := int32(len(src)) - inputMargin
 | |
| 	// stepSize is the number of bytes to skip on every main loop iteration.
 | |
| 	// It should be >= 2.
 | |
| 	const stepSize = 2
 | |
| 
 | |
| 	// TEMPLATE
 | |
| 	const hashLog = tableBits
 | |
| 	// seems global, but would be nice to tweak.
 | |
| 	const kSearchStrength = 8
 | |
| 
 | |
| 	// 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 debug {
 | |
| 		println("recent offsets:", blk.recentOffsets)
 | |
| 	}
 | |
| 
 | |
| encodeLoop:
 | |
| 	for {
 | |
| 		// t will contain the match offset when we find one.
 | |
| 		// When existing the search loop, we have already checked 4 bytes.
 | |
| 		var t int32
 | |
| 
 | |
| 		// We will not use repeat offsets across blocks.
 | |
| 		// By not using them for the first 3 matches
 | |
| 
 | |
| 		for {
 | |
| 			nextHash := hash6(cv, hashLog)
 | |
| 			nextHash2 := hash6(cv>>8, hashLog)
 | |
| 			candidate := e.table[nextHash]
 | |
| 			candidate2 := e.table[nextHash2]
 | |
| 			repIndex := s - offset1 + 2
 | |
| 
 | |
| 			e.table[nextHash] = tableEntry{offset: s + e.cur, val: uint32(cv)}
 | |
| 			e.table[nextHash2] = tableEntry{offset: s + e.cur + 1, val: uint32(cv >> 8)}
 | |
| 
 | |
| 			if len(blk.sequences) > 2 && load3232(src, repIndex) == uint32(cv>>16) {
 | |
| 				// Consider history as well.
 | |
| 				var seq seq
 | |
| 				// length := 4 + e.matchlen(s+6, repIndex+4, src)
 | |
| 				// length := 4 + int32(matchLen(src[s+6:], src[repIndex+4:]))
 | |
| 				var length int32
 | |
| 				{
 | |
| 					a := src[s+6:]
 | |
| 					b := src[repIndex+4:]
 | |
| 					endI := len(a) & (math.MaxInt32 - 7)
 | |
| 					length = int32(endI) + 4
 | |
| 					for i := 0; i < endI; i += 8 {
 | |
| 						if diff := load64(a, i) ^ load64(b, i); diff != 0 {
 | |
| 							length = int32(i+bits.TrailingZeros64(diff)>>3) + 4
 | |
| 							break
 | |
| 						}
 | |
| 					}
 | |
| 				}
 | |
| 
 | |
| 				seq.matchLen = uint32(length - zstdMinMatch)
 | |
| 
 | |
| 				// We might be able to match backwards.
 | |
| 				// Extend as long as we can.
 | |
| 				start := s + 2
 | |
| 				// We end the search early, so we don't risk 0 literals
 | |
| 				// and have to do special offset treatment.
 | |
| 				startLimit := nextEmit + 1
 | |
| 
 | |
| 				sMin := s - e.maxMatchOff
 | |
| 				if sMin < 0 {
 | |
| 					sMin = 0
 | |
| 				}
 | |
| 				for repIndex > sMin && start > startLimit && src[repIndex-1] == src[start-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)
 | |
| 				s += length + 2
 | |
| 				nextEmit = s
 | |
| 				if s >= sLimit {
 | |
| 					if debug {
 | |
| 						println("repeat ended", s, length)
 | |
| 
 | |
| 					}
 | |
| 					break encodeLoop
 | |
| 				}
 | |
| 				cv = load6432(src, s)
 | |
| 				continue
 | |
| 			}
 | |
| 			coffset0 := s - (candidate.offset - e.cur)
 | |
| 			coffset1 := s - (candidate2.offset - e.cur) + 1
 | |
| 			if coffset0 < e.maxMatchOff && uint32(cv) == candidate.val {
 | |
| 				// found a regular match
 | |
| 				t = candidate.offset - e.cur
 | |
| 				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(fmt.Sprintf("t (%d) < 0, candidate.offset: %d, e.cur: %d, coffset0: %d, e.maxMatchOff: %d", t, candidate.offset, e.cur, coffset0, e.maxMatchOff))
 | |
| 				}
 | |
| 				break
 | |
| 			}
 | |
| 
 | |
| 			if coffset1 < e.maxMatchOff && uint32(cv>>8) == candidate2.val {
 | |
| 				// found a regular match
 | |
| 				t = candidate2.offset - e.cur
 | |
| 				s++
 | |
| 				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")
 | |
| 				}
 | |
| 				break
 | |
| 			}
 | |
| 			s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
 | |
| 			if s >= sLimit {
 | |
| 				break encodeLoop
 | |
| 			}
 | |
| 			cv = load6432(src, s)
 | |
| 		}
 | |
| 		// A 4-byte match has been found. We'll later see if more than 4 bytes.
 | |
| 		offset2 = offset1
 | |
| 		offset1 = s - t
 | |
| 
 | |
| 		if debugAsserts && s <= t {
 | |
| 			panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
 | |
| 		}
 | |
| 
 | |
| 		if debugAsserts && t < 0 {
 | |
| 			panic(fmt.Sprintf("t (%d) < 0 ", t))
 | |
| 		}
 | |
| 		// Extend the 4-byte match as long as possible.
 | |
| 		//l := e.matchlenNoHist(s+4, t+4, src) + 4
 | |
| 		// l := int32(matchLen(src[s+4:], src[t+4:])) + 4
 | |
| 		var l int32
 | |
| 		{
 | |
| 			a := src[s+4:]
 | |
| 			b := src[t+4:]
 | |
| 			endI := len(a) & (math.MaxInt32 - 7)
 | |
| 			l = int32(endI) + 4
 | |
| 			for i := 0; i < endI; i += 8 {
 | |
| 				if diff := load64(a, i) ^ load64(b, i); diff != 0 {
 | |
| 					l = int32(i+bits.TrailingZeros64(diff)>>3) + 4
 | |
| 					break
 | |
| 				}
 | |
| 			}
 | |
| 		}
 | |
| 
 | |
| 		// Extend backwards
 | |
| 		tMin := s - e.maxMatchOff
 | |
| 		if tMin < 0 {
 | |
| 			tMin = 0
 | |
| 		}
 | |
| 		for t > tMin && s > nextEmit && src[t-1] == src[s-1] {
 | |
| 			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]...)
 | |
| 		}
 | |
| 		// Don't use repeat offsets
 | |
| 		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
 | |
| 		}
 | |
| 		cv = load6432(src, s)
 | |
| 
 | |
| 		// Check offset 2
 | |
| 		if o2 := s - offset2; len(blk.sequences) > 2 && load3232(src, o2) == uint32(cv) {
 | |
| 			// We have at least 4 byte match.
 | |
| 			// No need to check backwards. We come straight from a match
 | |
| 			//l := 4 + e.matchlenNoHist(s+4, o2+4, src)
 | |
| 			// l := 4 + int32(matchLen(src[s+4:], src[o2+4:]))
 | |
| 			var l int32
 | |
| 			{
 | |
| 				a := src[s+4:]
 | |
| 				b := src[o2+4:]
 | |
| 				endI := len(a) & (math.MaxInt32 - 7)
 | |
| 				l = int32(endI) + 4
 | |
| 				for i := 0; i < endI; i += 8 {
 | |
| 					if diff := load64(a, i) ^ load64(b, i); diff != 0 {
 | |
| 						l = int32(i+bits.TrailingZeros64(diff)>>3) + 4
 | |
| 						break
 | |
| 					}
 | |
| 				}
 | |
| 			}
 | |
| 
 | |
| 			// Store this, since we have it.
 | |
| 			nextHash := hash6(cv, hashLog)
 | |
| 			e.table[nextHash] = 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 {
 | |
| 				break encodeLoop
 | |
| 			}
 | |
| 			// Prepare next loop.
 | |
| 			cv = load6432(src, s)
 | |
| 		}
 | |
| 	}
 | |
| 
 | |
| 	if int(nextEmit) < len(src) {
 | |
| 		blk.literals = append(blk.literals, src[nextEmit:]...)
 | |
| 		blk.extraLits = len(src) - int(nextEmit)
 | |
| 	}
 | |
| 	if debug {
 | |
| 		println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
 | |
| 	}
 | |
| 	// We do not store history, so we must offset e.cur to avoid false matches for next user.
 | |
| 	if e.cur < bufferReset {
 | |
| 		e.cur += int32(len(src))
 | |
| 	}
 | |
| }
 | |
| 
 | |
| // ResetDict will reset and set a dictionary if not nil
 | |
| func (e *fastEncoder) 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))
 | |
| 		}
 | |
| 		if true {
 | |
| 			end := e.maxMatchOff + int32(len(d.content)) - 8
 | |
| 			for i := e.maxMatchOff; i < end; i += 3 {
 | |
| 				const hashLog = tableBits
 | |
| 
 | |
| 				cv := load6432(d.content, i-e.maxMatchOff)
 | |
| 				nextHash := hash6(cv, hashLog)      // 0 -> 5
 | |
| 				nextHash1 := hash6(cv>>8, hashLog)  // 1 -> 6
 | |
| 				nextHash2 := hash6(cv>>16, hashLog) // 2 -> 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.lastDictID = d.id
 | |
| 	}
 | |
| 
 | |
| 	e.cur = e.maxMatchOff
 | |
| 	// Reset table to initial state
 | |
| 	copy(e.table[:], e.dictTable)
 | |
| }
 |