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-rw-r--r--vendor/github.com/klauspost/compress/fse/compress.go683
1 files changed, 683 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/fse/compress.go b/vendor/github.com/klauspost/compress/fse/compress.go
new file mode 100644
index 00000000..6f341914
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/fse/compress.go
@@ -0,0 +1,683 @@
+// Copyright 2018 Klaus Post. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
+
+package fse
+
+import (
+ "errors"
+ "fmt"
+)
+
+// Compress the input bytes. Input must be < 2GB.
+// Provide a Scratch buffer to avoid memory allocations.
+// Note that the output is also kept in the scratch buffer.
+// If input is too hard to compress, ErrIncompressible is returned.
+// If input is a single byte value repeated ErrUseRLE is returned.
+func Compress(in []byte, s *Scratch) ([]byte, error) {
+ if len(in) <= 1 {
+ return nil, ErrIncompressible
+ }
+ if len(in) > (2<<30)-1 {
+ return nil, errors.New("input too big, must be < 2GB")
+ }
+ s, err := s.prepare(in)
+ if err != nil {
+ return nil, err
+ }
+
+ // Create histogram, if none was provided.
+ maxCount := s.maxCount
+ if maxCount == 0 {
+ maxCount = s.countSimple(in)
+ }
+ // Reset for next run.
+ s.clearCount = true
+ s.maxCount = 0
+ if maxCount == len(in) {
+ // One symbol, use RLE
+ return nil, ErrUseRLE
+ }
+ if maxCount == 1 || maxCount < (len(in)>>7) {
+ // Each symbol present maximum once or too well distributed.
+ return nil, ErrIncompressible
+ }
+ s.optimalTableLog()
+ err = s.normalizeCount()
+ if err != nil {
+ return nil, err
+ }
+ err = s.writeCount()
+ if err != nil {
+ return nil, err
+ }
+
+ if false {
+ err = s.validateNorm()
+ if err != nil {
+ return nil, err
+ }
+ }
+
+ err = s.buildCTable()
+ if err != nil {
+ return nil, err
+ }
+ err = s.compress(in)
+ if err != nil {
+ return nil, err
+ }
+ s.Out = s.bw.out
+ // Check if we compressed.
+ if len(s.Out) >= len(in) {
+ return nil, ErrIncompressible
+ }
+ return s.Out, nil
+}
+
+// cState contains the compression state of a stream.
+type cState struct {
+ bw *bitWriter
+ stateTable []uint16
+ state uint16
+}
+
+// init will initialize the compression state to the first symbol of the stream.
+func (c *cState) init(bw *bitWriter, ct *cTable, tableLog uint8, first symbolTransform) {
+ c.bw = bw
+ c.stateTable = ct.stateTable
+
+ nbBitsOut := (first.deltaNbBits + (1 << 15)) >> 16
+ im := int32((nbBitsOut << 16) - first.deltaNbBits)
+ lu := (im >> nbBitsOut) + first.deltaFindState
+ c.state = c.stateTable[lu]
+}
+
+// encode the output symbol provided and write it to the bitstream.
+func (c *cState) encode(symbolTT symbolTransform) {
+ nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
+ dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
+ c.bw.addBits16NC(c.state, uint8(nbBitsOut))
+ c.state = c.stateTable[dstState]
+}
+
+// encode the output symbol provided and write it to the bitstream.
+func (c *cState) encodeZero(symbolTT symbolTransform) {
+ nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
+ dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
+ c.bw.addBits16ZeroNC(c.state, uint8(nbBitsOut))
+ c.state = c.stateTable[dstState]
+}
+
+// flush will write the tablelog to the output and flush the remaining full bytes.
+func (c *cState) flush(tableLog uint8) {
+ c.bw.flush32()
+ c.bw.addBits16NC(c.state, tableLog)
+ c.bw.flush()
+}
+
+// compress is the main compression loop that will encode the input from the last byte to the first.
+func (s *Scratch) compress(src []byte) error {
+ if len(src) <= 2 {
+ return errors.New("compress: src too small")
+ }
+ tt := s.ct.symbolTT[:256]
+ s.bw.reset(s.Out)
+
+ // Our two states each encodes every second byte.
+ // Last byte encoded (first byte decoded) will always be encoded by c1.
+ var c1, c2 cState
+
+ // Encode so remaining size is divisible by 4.
+ ip := len(src)
+ if ip&1 == 1 {
+ c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
+ c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
+ c1.encodeZero(tt[src[ip-3]])
+ ip -= 3
+ } else {
+ c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
+ c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
+ ip -= 2
+ }
+ if ip&2 != 0 {
+ c2.encodeZero(tt[src[ip-1]])
+ c1.encodeZero(tt[src[ip-2]])
+ ip -= 2
+ }
+
+ // Main compression loop.
+ switch {
+ case !s.zeroBits && s.actualTableLog <= 8:
+ // We can encode 4 symbols without requiring a flush.
+ // We do not need to check if any output is 0 bits.
+ for ip >= 4 {
+ s.bw.flush32()
+ v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
+ c2.encode(tt[v0])
+ c1.encode(tt[v1])
+ c2.encode(tt[v2])
+ c1.encode(tt[v3])
+ ip -= 4
+ }
+ case !s.zeroBits:
+ // We do not need to check if any output is 0 bits.
+ for ip >= 4 {
+ s.bw.flush32()
+ v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
+ c2.encode(tt[v0])
+ c1.encode(tt[v1])
+ s.bw.flush32()
+ c2.encode(tt[v2])
+ c1.encode(tt[v3])
+ ip -= 4
+ }
+ case s.actualTableLog <= 8:
+ // We can encode 4 symbols without requiring a flush
+ for ip >= 4 {
+ s.bw.flush32()
+ v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
+ c2.encodeZero(tt[v0])
+ c1.encodeZero(tt[v1])
+ c2.encodeZero(tt[v2])
+ c1.encodeZero(tt[v3])
+ ip -= 4
+ }
+ default:
+ for ip >= 4 {
+ s.bw.flush32()
+ v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
+ c2.encodeZero(tt[v0])
+ c1.encodeZero(tt[v1])
+ s.bw.flush32()
+ c2.encodeZero(tt[v2])
+ c1.encodeZero(tt[v3])
+ ip -= 4
+ }
+ }
+
+ // Flush final state.
+ // Used to initialize state when decoding.
+ c2.flush(s.actualTableLog)
+ c1.flush(s.actualTableLog)
+
+ return s.bw.close()
+}
+
+// writeCount will write the normalized histogram count to header.
+// This is read back by readNCount.
+func (s *Scratch) writeCount() error {
+ var (
+ tableLog = s.actualTableLog
+ tableSize = 1 << tableLog
+ previous0 bool
+ charnum uint16
+
+ maxHeaderSize = ((int(s.symbolLen) * int(tableLog)) >> 3) + 3
+
+ // Write Table Size
+ bitStream = uint32(tableLog - minTablelog)
+ bitCount = uint(4)
+ remaining = int16(tableSize + 1) /* +1 for extra accuracy */
+ threshold = int16(tableSize)
+ nbBits = uint(tableLog + 1)
+ )
+ if cap(s.Out) < maxHeaderSize {
+ s.Out = make([]byte, 0, s.br.remain()+maxHeaderSize)
+ }
+ outP := uint(0)
+ out := s.Out[:maxHeaderSize]
+
+ // stops at 1
+ for remaining > 1 {
+ if previous0 {
+ start := charnum
+ for s.norm[charnum] == 0 {
+ charnum++
+ }
+ for charnum >= start+24 {
+ start += 24
+ bitStream += uint32(0xFFFF) << bitCount
+ out[outP] = byte(bitStream)
+ out[outP+1] = byte(bitStream >> 8)
+ outP += 2
+ bitStream >>= 16
+ }
+ for charnum >= start+3 {
+ start += 3
+ bitStream += 3 << bitCount
+ bitCount += 2
+ }
+ bitStream += uint32(charnum-start) << bitCount
+ bitCount += 2
+ if bitCount > 16 {
+ out[outP] = byte(bitStream)
+ out[outP+1] = byte(bitStream >> 8)
+ outP += 2
+ bitStream >>= 16
+ bitCount -= 16
+ }
+ }
+
+ count := s.norm[charnum]
+ charnum++
+ max := (2*threshold - 1) - remaining
+ if count < 0 {
+ remaining += count
+ } else {
+ remaining -= count
+ }
+ count++ // +1 for extra accuracy
+ if count >= threshold {
+ count += max // [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[
+ }
+ bitStream += uint32(count) << bitCount
+ bitCount += nbBits
+ if count < max {
+ bitCount--
+ }
+
+ previous0 = count == 1
+ if remaining < 1 {
+ return errors.New("internal error: remaining<1")
+ }
+ for remaining < threshold {
+ nbBits--
+ threshold >>= 1
+ }
+
+ if bitCount > 16 {
+ out[outP] = byte(bitStream)
+ out[outP+1] = byte(bitStream >> 8)
+ outP += 2
+ bitStream >>= 16
+ bitCount -= 16
+ }
+ }
+
+ out[outP] = byte(bitStream)
+ out[outP+1] = byte(bitStream >> 8)
+ outP += (bitCount + 7) / 8
+
+ if charnum > s.symbolLen {
+ return errors.New("internal error: charnum > s.symbolLen")
+ }
+ s.Out = out[:outP]
+ return nil
+}
+
+// symbolTransform contains the state transform for a symbol.
+type symbolTransform struct {
+ deltaFindState int32
+ deltaNbBits uint32
+}
+
+// String prints values as a human readable string.
+func (s symbolTransform) String() string {
+ return fmt.Sprintf("dnbits: %08x, fs:%d", s.deltaNbBits, s.deltaFindState)
+}
+
+// cTable contains tables used for compression.
+type cTable struct {
+ tableSymbol []byte
+ stateTable []uint16
+ symbolTT []symbolTransform
+}
+
+// allocCtable will allocate tables needed for compression.
+// If existing tables a re big enough, they are simply re-used.
+func (s *Scratch) allocCtable() {
+ tableSize := 1 << s.actualTableLog
+ // get tableSymbol that is big enough.
+ if cap(s.ct.tableSymbol) < tableSize {
+ s.ct.tableSymbol = make([]byte, tableSize)
+ }
+ s.ct.tableSymbol = s.ct.tableSymbol[:tableSize]
+
+ ctSize := tableSize
+ if cap(s.ct.stateTable) < ctSize {
+ s.ct.stateTable = make([]uint16, ctSize)
+ }
+ s.ct.stateTable = s.ct.stateTable[:ctSize]
+
+ if cap(s.ct.symbolTT) < 256 {
+ s.ct.symbolTT = make([]symbolTransform, 256)
+ }
+ s.ct.symbolTT = s.ct.symbolTT[:256]
+}
+
+// buildCTable will populate the compression table so it is ready to be used.
+func (s *Scratch) buildCTable() error {
+ tableSize := uint32(1 << s.actualTableLog)
+ highThreshold := tableSize - 1
+ var cumul [maxSymbolValue + 2]int16
+
+ s.allocCtable()
+ tableSymbol := s.ct.tableSymbol[:tableSize]
+ // symbol start positions
+ {
+ cumul[0] = 0
+ for ui, v := range s.norm[:s.symbolLen-1] {
+ u := byte(ui) // one less than reference
+ if v == -1 {
+ // Low proba symbol
+ cumul[u+1] = cumul[u] + 1
+ tableSymbol[highThreshold] = u
+ highThreshold--
+ } else {
+ cumul[u+1] = cumul[u] + v
+ }
+ }
+ // Encode last symbol separately to avoid overflowing u
+ u := int(s.symbolLen - 1)
+ v := s.norm[s.symbolLen-1]
+ if v == -1 {
+ // Low proba symbol
+ cumul[u+1] = cumul[u] + 1
+ tableSymbol[highThreshold] = byte(u)
+ highThreshold--
+ } else {
+ cumul[u+1] = cumul[u] + v
+ }
+ if uint32(cumul[s.symbolLen]) != tableSize {
+ return fmt.Errorf("internal error: expected cumul[s.symbolLen] (%d) == tableSize (%d)", cumul[s.symbolLen], tableSize)
+ }
+ cumul[s.symbolLen] = int16(tableSize) + 1
+ }
+ // Spread symbols
+ s.zeroBits = false
+ {
+ step := tableStep(tableSize)
+ tableMask := tableSize - 1
+ var position uint32
+ // if any symbol > largeLimit, we may have 0 bits output.
+ largeLimit := int16(1 << (s.actualTableLog - 1))
+ for ui, v := range s.norm[:s.symbolLen] {
+ symbol := byte(ui)
+ if v > largeLimit {
+ s.zeroBits = true
+ }
+ for nbOccurrences := int16(0); nbOccurrences < v; nbOccurrences++ {
+ tableSymbol[position] = symbol
+ position = (position + step) & tableMask
+ for position > highThreshold {
+ position = (position + step) & tableMask
+ } /* Low proba area */
+ }
+ }
+
+ // Check if we have gone through all positions
+ if position != 0 {
+ return errors.New("position!=0")
+ }
+ }
+
+ // Build table
+ table := s.ct.stateTable
+ {
+ tsi := int(tableSize)
+ for u, v := range tableSymbol {
+ // TableU16 : sorted by symbol order; gives next state value
+ table[cumul[v]] = uint16(tsi + u)
+ cumul[v]++
+ }
+ }
+
+ // Build Symbol Transformation Table
+ {
+ total := int16(0)
+ symbolTT := s.ct.symbolTT[:s.symbolLen]
+ tableLog := s.actualTableLog
+ tl := (uint32(tableLog) << 16) - (1 << tableLog)
+ for i, v := range s.norm[:s.symbolLen] {
+ switch v {
+ case 0:
+ case -1, 1:
+ symbolTT[i].deltaNbBits = tl
+ symbolTT[i].deltaFindState = int32(total - 1)
+ total++
+ default:
+ maxBitsOut := uint32(tableLog) - highBits(uint32(v-1))
+ minStatePlus := uint32(v) << maxBitsOut
+ symbolTT[i].deltaNbBits = (maxBitsOut << 16) - minStatePlus
+ symbolTT[i].deltaFindState = int32(total - v)
+ total += v
+ }
+ }
+ if total != int16(tableSize) {
+ return fmt.Errorf("total mismatch %d (got) != %d (want)", total, tableSize)
+ }
+ }
+ return nil
+}
+
+// countSimple will create a simple histogram in s.count.
+// Returns the biggest count.
+// Does not update s.clearCount.
+func (s *Scratch) countSimple(in []byte) (max int) {
+ for _, v := range in {
+ s.count[v]++
+ }
+ m := uint32(0)
+ for i, v := range s.count[:] {
+ if v > m {
+ m = v
+ }
+ if v > 0 {
+ s.symbolLen = uint16(i) + 1
+ }
+ }
+ return int(m)
+}
+
+// minTableLog provides the minimum logSize to safely represent a distribution.
+func (s *Scratch) minTableLog() uint8 {
+ minBitsSrc := highBits(uint32(s.br.remain()-1)) + 1
+ minBitsSymbols := highBits(uint32(s.symbolLen-1)) + 2
+ if minBitsSrc < minBitsSymbols {
+ return uint8(minBitsSrc)
+ }
+ return uint8(minBitsSymbols)
+}
+
+// optimalTableLog calculates and sets the optimal tableLog in s.actualTableLog
+func (s *Scratch) optimalTableLog() {
+ tableLog := s.TableLog
+ minBits := s.minTableLog()
+ maxBitsSrc := uint8(highBits(uint32(s.br.remain()-1))) - 2
+ if maxBitsSrc < tableLog {
+ // Accuracy can be reduced
+ tableLog = maxBitsSrc
+ }
+ if minBits > tableLog {
+ tableLog = minBits
+ }
+ // Need a minimum to safely represent all symbol values
+ if tableLog < minTablelog {
+ tableLog = minTablelog
+ }
+ if tableLog > maxTableLog {
+ tableLog = maxTableLog
+ }
+ s.actualTableLog = tableLog
+}
+
+var rtbTable = [...]uint32{0, 473195, 504333, 520860, 550000, 700000, 750000, 830000}
+
+// normalizeCount will normalize the count of the symbols so
+// the total is equal to the table size.
+func (s *Scratch) normalizeCount() error {
+ var (
+ tableLog = s.actualTableLog
+ scale = 62 - uint64(tableLog)
+ step = (1 << 62) / uint64(s.br.remain())
+ vStep = uint64(1) << (scale - 20)
+ stillToDistribute = int16(1 << tableLog)
+ largest int
+ largestP int16
+ lowThreshold = (uint32)(s.br.remain() >> tableLog)
+ )
+
+ for i, cnt := range s.count[:s.symbolLen] {
+ // already handled
+ // if (count[s] == s.length) return 0; /* rle special case */
+
+ if cnt == 0 {
+ s.norm[i] = 0
+ continue
+ }
+ if cnt <= lowThreshold {
+ s.norm[i] = -1
+ stillToDistribute--
+ } else {
+ proba := (int16)((uint64(cnt) * step) >> scale)
+ if proba < 8 {
+ restToBeat := vStep * uint64(rtbTable[proba])
+ v := uint64(cnt)*step - (uint64(proba) << scale)
+ if v > restToBeat {
+ proba++
+ }
+ }
+ if proba > largestP {
+ largestP = proba
+ largest = i
+ }
+ s.norm[i] = proba
+ stillToDistribute -= proba
+ }
+ }
+
+ if -stillToDistribute >= (s.norm[largest] >> 1) {
+ // corner case, need another normalization method
+ return s.normalizeCount2()
+ }
+ s.norm[largest] += stillToDistribute
+ return nil
+}
+
+// Secondary normalization method.
+// To be used when primary method fails.
+func (s *Scratch) normalizeCount2() error {
+ const notYetAssigned = -2
+ var (
+ distributed uint32
+ total = uint32(s.br.remain())
+ tableLog = s.actualTableLog
+ lowThreshold = total >> tableLog
+ lowOne = (total * 3) >> (tableLog + 1)
+ )
+ for i, cnt := range s.count[:s.symbolLen] {
+ if cnt == 0 {
+ s.norm[i] = 0
+ continue
+ }
+ if cnt <= lowThreshold {
+ s.norm[i] = -1
+ distributed++
+ total -= cnt
+ continue
+ }
+ if cnt <= lowOne {
+ s.norm[i] = 1
+ distributed++
+ total -= cnt
+ continue
+ }
+ s.norm[i] = notYetAssigned
+ }
+ toDistribute := (1 << tableLog) - distributed
+
+ if (total / toDistribute) > lowOne {
+ // risk of rounding to zero
+ lowOne = (total * 3) / (toDistribute * 2)
+ for i, cnt := range s.count[:s.symbolLen] {
+ if (s.norm[i] == notYetAssigned) && (cnt <= lowOne) {
+ s.norm[i] = 1
+ distributed++
+ total -= cnt
+ continue
+ }
+ }
+ toDistribute = (1 << tableLog) - distributed
+ }
+ if distributed == uint32(s.symbolLen)+1 {
+ // all values are pretty poor;
+ // probably incompressible data (should have already been detected);
+ // find max, then give all remaining points to max
+ var maxV int
+ var maxC uint32
+ for i, cnt := range s.count[:s.symbolLen] {
+ if cnt > maxC {
+ maxV = i
+ maxC = cnt
+ }
+ }
+ s.norm[maxV] += int16(toDistribute)
+ return nil
+ }
+
+ if total == 0 {
+ // all of the symbols were low enough for the lowOne or lowThreshold
+ for i := uint32(0); toDistribute > 0; i = (i + 1) % (uint32(s.symbolLen)) {
+ if s.norm[i] > 0 {
+ toDistribute--
+ s.norm[i]++
+ }
+ }
+ return nil
+ }
+
+ var (
+ vStepLog = 62 - uint64(tableLog)
+ mid = uint64((1 << (vStepLog - 1)) - 1)
+ rStep = (((1 << vStepLog) * uint64(toDistribute)) + mid) / uint64(total) // scale on remaining
+ tmpTotal = mid
+ )
+ for i, cnt := range s.count[:s.symbolLen] {
+ if s.norm[i] == notYetAssigned {
+ var (
+ end = tmpTotal + uint64(cnt)*rStep
+ sStart = uint32(tmpTotal >> vStepLog)
+ sEnd = uint32(end >> vStepLog)
+ weight = sEnd - sStart
+ )
+ if weight < 1 {
+ return errors.New("weight < 1")
+ }
+ s.norm[i] = int16(weight)
+ tmpTotal = end
+ }
+ }
+ return nil
+}
+
+// validateNorm validates the normalized histogram table.
+func (s *Scratch) validateNorm() (err error) {
+ var total int
+ for _, v := range s.norm[:s.symbolLen] {
+ if v >= 0 {
+ total += int(v)
+ } else {
+ total -= int(v)
+ }
+ }
+ defer func() {
+ if err == nil {
+ return
+ }
+ fmt.Printf("selected TableLog: %d, Symbol length: %d\n", s.actualTableLog, s.symbolLen)
+ for i, v := range s.norm[:s.symbolLen] {
+ fmt.Printf("%3d: %5d -> %4d \n", i, s.count[i], v)
+ }
+ }()
+ if total != (1 << s.actualTableLog) {
+ return fmt.Errorf("warning: Total == %d != %d", total, 1<<s.actualTableLog)
+ }
+ for i, v := range s.count[s.symbolLen:] {
+ if v != 0 {
+ return fmt.Errorf("warning: Found symbol out of range, %d after cut", i)
+ }
+ }
+ return nil
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 08:07:45 +0000