summaryrefslogtreecommitdiffstats
path: root/vendor/github.com/klauspost/compress/huff0/compress.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/github.com/klauspost/compress/huff0/compress.go')
-rw-r--r--vendor/github.com/klauspost/compress/huff0/compress.go720
1 files changed, 720 insertions, 0 deletions
diff --git a/vendor/github.com/klauspost/compress/huff0/compress.go b/vendor/github.com/klauspost/compress/huff0/compress.go
new file mode 100644
index 00000000..8323dc05
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/huff0/compress.go
@@ -0,0 +1,720 @@
+package huff0
+
+import (
+ "fmt"
+ "runtime"
+ "sync"
+)
+
+// Compress1X will compress the input.
+// The output can be decoded using Decompress1X.
+// Supply a Scratch object. The scratch object contains state about re-use,
+// So when sharing across independent encodes, be sure to set the re-use policy.
+func Compress1X(in []byte, s *Scratch) (out []byte, reUsed bool, err error) {
+ s, err = s.prepare(in)
+ if err != nil {
+ return nil, false, err
+ }
+ return compress(in, s, s.compress1X)
+}
+
+// Compress4X will compress the input. The input is split into 4 independent blocks
+// and compressed similar to Compress1X.
+// The output can be decoded using Decompress4X.
+// Supply a Scratch object. The scratch object contains state about re-use,
+// So when sharing across independent encodes, be sure to set the re-use policy.
+func Compress4X(in []byte, s *Scratch) (out []byte, reUsed bool, err error) {
+ s, err = s.prepare(in)
+ if err != nil {
+ return nil, false, err
+ }
+ if false {
+ // TODO: compress4Xp only slightly faster.
+ const parallelThreshold = 8 << 10
+ if len(in) < parallelThreshold || runtime.GOMAXPROCS(0) == 1 {
+ return compress(in, s, s.compress4X)
+ }
+ return compress(in, s, s.compress4Xp)
+ }
+ return compress(in, s, s.compress4X)
+}
+
+func compress(in []byte, s *Scratch, compressor func(src []byte) ([]byte, error)) (out []byte, reUsed bool, err error) {
+ // Nuke previous table if we cannot reuse anyway.
+ if s.Reuse == ReusePolicyNone {
+ s.prevTable = s.prevTable[:0]
+ }
+
+ // Create histogram, if none was provided.
+ maxCount := s.maxCount
+ var canReuse = false
+ if maxCount == 0 {
+ maxCount, canReuse = s.countSimple(in)
+ } else {
+ canReuse = s.canUseTable(s.prevTable)
+ }
+
+ // We want the output size to be less than this:
+ wantSize := len(in)
+ if s.WantLogLess > 0 {
+ wantSize -= wantSize >> s.WantLogLess
+ }
+
+ // Reset for next run.
+ s.clearCount = true
+ s.maxCount = 0
+ if maxCount >= len(in) {
+ if maxCount > len(in) {
+ return nil, false, fmt.Errorf("maxCount (%d) > length (%d)", maxCount, len(in))
+ }
+ if len(in) == 1 {
+ return nil, false, ErrIncompressible
+ }
+ // One symbol, use RLE
+ return nil, false, ErrUseRLE
+ }
+ if maxCount == 1 || maxCount < (len(in)>>7) {
+ // Each symbol present maximum once or too well distributed.
+ return nil, false, ErrIncompressible
+ }
+ if s.Reuse == ReusePolicyMust && !canReuse {
+ // We must reuse, but we can't.
+ return nil, false, ErrIncompressible
+ }
+ if (s.Reuse == ReusePolicyPrefer || s.Reuse == ReusePolicyMust) && canReuse {
+ keepTable := s.cTable
+ keepTL := s.actualTableLog
+ s.cTable = s.prevTable
+ s.actualTableLog = s.prevTableLog
+ s.Out, err = compressor(in)
+ s.cTable = keepTable
+ s.actualTableLog = keepTL
+ if err == nil && len(s.Out) < wantSize {
+ s.OutData = s.Out
+ return s.Out, true, nil
+ }
+ if s.Reuse == ReusePolicyMust {
+ return nil, false, ErrIncompressible
+ }
+ // Do not attempt to re-use later.
+ s.prevTable = s.prevTable[:0]
+ }
+
+ // Calculate new table.
+ err = s.buildCTable()
+ if err != nil {
+ return nil, false, err
+ }
+
+ if false && !s.canUseTable(s.cTable) {
+ panic("invalid table generated")
+ }
+
+ if s.Reuse == ReusePolicyAllow && canReuse {
+ hSize := len(s.Out)
+ oldSize := s.prevTable.estimateSize(s.count[:s.symbolLen])
+ newSize := s.cTable.estimateSize(s.count[:s.symbolLen])
+ if oldSize <= hSize+newSize || hSize+12 >= wantSize {
+ // Retain cTable even if we re-use.
+ keepTable := s.cTable
+ keepTL := s.actualTableLog
+
+ s.cTable = s.prevTable
+ s.actualTableLog = s.prevTableLog
+ s.Out, err = compressor(in)
+
+ // Restore ctable.
+ s.cTable = keepTable
+ s.actualTableLog = keepTL
+ if err != nil {
+ return nil, false, err
+ }
+ if len(s.Out) >= wantSize {
+ return nil, false, ErrIncompressible
+ }
+ s.OutData = s.Out
+ return s.Out, true, nil
+ }
+ }
+
+ // Use new table
+ err = s.cTable.write(s)
+ if err != nil {
+ s.OutTable = nil
+ return nil, false, err
+ }
+ s.OutTable = s.Out
+
+ // Compress using new table
+ s.Out, err = compressor(in)
+ if err != nil {
+ s.OutTable = nil
+ return nil, false, err
+ }
+ if len(s.Out) >= wantSize {
+ s.OutTable = nil
+ return nil, false, ErrIncompressible
+ }
+ // Move current table into previous.
+ s.prevTable, s.prevTableLog, s.cTable = s.cTable, s.actualTableLog, s.prevTable[:0]
+ s.OutData = s.Out[len(s.OutTable):]
+ return s.Out, false, nil
+}
+
+// EstimateSizes will estimate the data sizes
+func EstimateSizes(in []byte, s *Scratch) (tableSz, dataSz, reuseSz int, err error) {
+ s, err = s.prepare(in)
+ if err != nil {
+ return 0, 0, 0, err
+ }
+
+ // Create histogram, if none was provided.
+ tableSz, dataSz, reuseSz = -1, -1, -1
+ maxCount := s.maxCount
+ var canReuse = false
+ if maxCount == 0 {
+ maxCount, canReuse = s.countSimple(in)
+ } else {
+ canReuse = s.canUseTable(s.prevTable)
+ }
+
+ // We want the output size to be less than this:
+ wantSize := len(in)
+ if s.WantLogLess > 0 {
+ wantSize -= wantSize >> s.WantLogLess
+ }
+
+ // Reset for next run.
+ s.clearCount = true
+ s.maxCount = 0
+ if maxCount >= len(in) {
+ if maxCount > len(in) {
+ return 0, 0, 0, fmt.Errorf("maxCount (%d) > length (%d)", maxCount, len(in))
+ }
+ if len(in) == 1 {
+ return 0, 0, 0, ErrIncompressible
+ }
+ // One symbol, use RLE
+ return 0, 0, 0, ErrUseRLE
+ }
+ if maxCount == 1 || maxCount < (len(in)>>7) {
+ // Each symbol present maximum once or too well distributed.
+ return 0, 0, 0, ErrIncompressible
+ }
+
+ // Calculate new table.
+ err = s.buildCTable()
+ if err != nil {
+ return 0, 0, 0, err
+ }
+
+ if false && !s.canUseTable(s.cTable) {
+ panic("invalid table generated")
+ }
+
+ tableSz, err = s.cTable.estTableSize(s)
+ if err != nil {
+ return 0, 0, 0, err
+ }
+ if canReuse {
+ reuseSz = s.prevTable.estimateSize(s.count[:s.symbolLen])
+ }
+ dataSz = s.cTable.estimateSize(s.count[:s.symbolLen])
+
+ // Restore
+ return tableSz, dataSz, reuseSz, nil
+}
+
+func (s *Scratch) compress1X(src []byte) ([]byte, error) {
+ return s.compress1xDo(s.Out, src)
+}
+
+func (s *Scratch) compress1xDo(dst, src []byte) ([]byte, error) {
+ var bw = bitWriter{out: dst}
+
+ // N is length divisible by 4.
+ n := len(src)
+ n -= n & 3
+ cTable := s.cTable[:256]
+
+ // Encode last bytes.
+ for i := len(src) & 3; i > 0; i-- {
+ bw.encSymbol(cTable, src[n+i-1])
+ }
+ n -= 4
+ if s.actualTableLog <= 8 {
+ for ; n >= 0; n -= 4 {
+ tmp := src[n : n+4]
+ // tmp should be len 4
+ bw.flush32()
+ bw.encTwoSymbols(cTable, tmp[3], tmp[2])
+ bw.encTwoSymbols(cTable, tmp[1], tmp[0])
+ }
+ } else {
+ for ; n >= 0; n -= 4 {
+ tmp := src[n : n+4]
+ // tmp should be len 4
+ bw.flush32()
+ bw.encTwoSymbols(cTable, tmp[3], tmp[2])
+ bw.flush32()
+ bw.encTwoSymbols(cTable, tmp[1], tmp[0])
+ }
+ }
+ err := bw.close()
+ return bw.out, err
+}
+
+var sixZeros [6]byte
+
+func (s *Scratch) compress4X(src []byte) ([]byte, error) {
+ if len(src) < 12 {
+ return nil, ErrIncompressible
+ }
+ segmentSize := (len(src) + 3) / 4
+
+ // Add placeholder for output length
+ offsetIdx := len(s.Out)
+ s.Out = append(s.Out, sixZeros[:]...)
+
+ for i := 0; i < 4; i++ {
+ toDo := src
+ if len(toDo) > segmentSize {
+ toDo = toDo[:segmentSize]
+ }
+ src = src[len(toDo):]
+
+ var err error
+ idx := len(s.Out)
+ s.Out, err = s.compress1xDo(s.Out, toDo)
+ if err != nil {
+ return nil, err
+ }
+ // Write compressed length as little endian before block.
+ if i < 3 {
+ // Last length is not written.
+ length := len(s.Out) - idx
+ s.Out[i*2+offsetIdx] = byte(length)
+ s.Out[i*2+offsetIdx+1] = byte(length >> 8)
+ }
+ }
+
+ return s.Out, nil
+}
+
+// compress4Xp will compress 4 streams using separate goroutines.
+func (s *Scratch) compress4Xp(src []byte) ([]byte, error) {
+ if len(src) < 12 {
+ return nil, ErrIncompressible
+ }
+ // Add placeholder for output length
+ s.Out = s.Out[:6]
+
+ segmentSize := (len(src) + 3) / 4
+ var wg sync.WaitGroup
+ var errs [4]error
+ wg.Add(4)
+ for i := 0; i < 4; i++ {
+ toDo := src
+ if len(toDo) > segmentSize {
+ toDo = toDo[:segmentSize]
+ }
+ src = src[len(toDo):]
+
+ // Separate goroutine for each block.
+ go func(i int) {
+ s.tmpOut[i], errs[i] = s.compress1xDo(s.tmpOut[i][:0], toDo)
+ wg.Done()
+ }(i)
+ }
+ wg.Wait()
+ for i := 0; i < 4; i++ {
+ if errs[i] != nil {
+ return nil, errs[i]
+ }
+ o := s.tmpOut[i]
+ // Write compressed length as little endian before block.
+ if i < 3 {
+ // Last length is not written.
+ s.Out[i*2] = byte(len(o))
+ s.Out[i*2+1] = byte(len(o) >> 8)
+ }
+
+ // Write output.
+ s.Out = append(s.Out, o...)
+ }
+ return s.Out, 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, reuse bool) {
+ reuse = true
+ for _, v := range in {
+ s.count[v]++
+ }
+ m := uint32(0)
+ if len(s.prevTable) > 0 {
+ for i, v := range s.count[:] {
+ if v > m {
+ m = v
+ }
+ if v > 0 {
+ s.symbolLen = uint16(i) + 1
+ if i >= len(s.prevTable) {
+ reuse = false
+ } else {
+ if s.prevTable[i].nBits == 0 {
+ reuse = false
+ }
+ }
+ }
+ }
+ return int(m), reuse
+ }
+ for i, v := range s.count[:] {
+ if v > m {
+ m = v
+ }
+ if v > 0 {
+ s.symbolLen = uint16(i) + 1
+ }
+ }
+ return int(m), false
+}
+
+func (s *Scratch) canUseTable(c cTable) bool {
+ if len(c) < int(s.symbolLen) {
+ return false
+ }
+ for i, v := range s.count[:s.symbolLen] {
+ if v != 0 && c[i].nBits == 0 {
+ return false
+ }
+ }
+ return true
+}
+
+func (s *Scratch) validateTable(c cTable) bool {
+ if len(c) < int(s.symbolLen) {
+ return false
+ }
+ for i, v := range s.count[:s.symbolLen] {
+ if v != 0 {
+ if c[i].nBits == 0 {
+ return false
+ }
+ if c[i].nBits > s.actualTableLog {
+ return false
+ }
+ }
+ }
+ return true
+}
+
+// minTableLog provides the minimum logSize to safely represent a distribution.
+func (s *Scratch) minTableLog() uint8 {
+ minBitsSrc := highBit32(uint32(s.br.remain())) + 1
+ minBitsSymbols := highBit32(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(highBit32(uint32(s.br.remain()-1))) - 1
+ 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 > tableLogMax {
+ tableLog = tableLogMax
+ }
+ s.actualTableLog = tableLog
+}
+
+type cTableEntry struct {
+ val uint16
+ nBits uint8
+ // We have 8 bits extra
+}
+
+const huffNodesMask = huffNodesLen - 1
+
+func (s *Scratch) buildCTable() error {
+ s.optimalTableLog()
+ s.huffSort()
+ if cap(s.cTable) < maxSymbolValue+1 {
+ s.cTable = make([]cTableEntry, s.symbolLen, maxSymbolValue+1)
+ } else {
+ s.cTable = s.cTable[:s.symbolLen]
+ for i := range s.cTable {
+ s.cTable[i] = cTableEntry{}
+ }
+ }
+
+ var startNode = int16(s.symbolLen)
+ nonNullRank := s.symbolLen - 1
+
+ nodeNb := startNode
+ huffNode := s.nodes[1 : huffNodesLen+1]
+
+ // This overlays the slice above, but allows "-1" index lookups.
+ // Different from reference implementation.
+ huffNode0 := s.nodes[0 : huffNodesLen+1]
+
+ for huffNode[nonNullRank].count == 0 {
+ nonNullRank--
+ }
+
+ lowS := int16(nonNullRank)
+ nodeRoot := nodeNb + lowS - 1
+ lowN := nodeNb
+ huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS-1].count
+ huffNode[lowS].parent, huffNode[lowS-1].parent = uint16(nodeNb), uint16(nodeNb)
+ nodeNb++
+ lowS -= 2
+ for n := nodeNb; n <= nodeRoot; n++ {
+ huffNode[n].count = 1 << 30
+ }
+ // fake entry, strong barrier
+ huffNode0[0].count = 1 << 31
+
+ // create parents
+ for nodeNb <= nodeRoot {
+ var n1, n2 int16
+ if huffNode0[lowS+1].count < huffNode0[lowN+1].count {
+ n1 = lowS
+ lowS--
+ } else {
+ n1 = lowN
+ lowN++
+ }
+ if huffNode0[lowS+1].count < huffNode0[lowN+1].count {
+ n2 = lowS
+ lowS--
+ } else {
+ n2 = lowN
+ lowN++
+ }
+
+ huffNode[nodeNb].count = huffNode0[n1+1].count + huffNode0[n2+1].count
+ huffNode0[n1+1].parent, huffNode0[n2+1].parent = uint16(nodeNb), uint16(nodeNb)
+ nodeNb++
+ }
+
+ // distribute weights (unlimited tree height)
+ huffNode[nodeRoot].nbBits = 0
+ for n := nodeRoot - 1; n >= startNode; n-- {
+ huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1
+ }
+ for n := uint16(0); n <= nonNullRank; n++ {
+ huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1
+ }
+ s.actualTableLog = s.setMaxHeight(int(nonNullRank))
+ maxNbBits := s.actualTableLog
+
+ // fill result into tree (val, nbBits)
+ if maxNbBits > tableLogMax {
+ return fmt.Errorf("internal error: maxNbBits (%d) > tableLogMax (%d)", maxNbBits, tableLogMax)
+ }
+ var nbPerRank [tableLogMax + 1]uint16
+ var valPerRank [16]uint16
+ for _, v := range huffNode[:nonNullRank+1] {
+ nbPerRank[v.nbBits]++
+ }
+ // determine stating value per rank
+ {
+ min := uint16(0)
+ for n := maxNbBits; n > 0; n-- {
+ // get starting value within each rank
+ valPerRank[n] = min
+ min += nbPerRank[n]
+ min >>= 1
+ }
+ }
+
+ // push nbBits per symbol, symbol order
+ for _, v := range huffNode[:nonNullRank+1] {
+ s.cTable[v.symbol].nBits = v.nbBits
+ }
+
+ // assign value within rank, symbol order
+ t := s.cTable[:s.symbolLen]
+ for n, val := range t {
+ nbits := val.nBits & 15
+ v := valPerRank[nbits]
+ t[n].val = v
+ valPerRank[nbits] = v + 1
+ }
+
+ return nil
+}
+
+// huffSort will sort symbols, decreasing order.
+func (s *Scratch) huffSort() {
+ type rankPos struct {
+ base uint32
+ current uint32
+ }
+
+ // Clear nodes
+ nodes := s.nodes[:huffNodesLen+1]
+ s.nodes = nodes
+ nodes = nodes[1 : huffNodesLen+1]
+
+ // Sort into buckets based on length of symbol count.
+ var rank [32]rankPos
+ for _, v := range s.count[:s.symbolLen] {
+ r := highBit32(v+1) & 31
+ rank[r].base++
+ }
+ // maxBitLength is log2(BlockSizeMax) + 1
+ const maxBitLength = 18 + 1
+ for n := maxBitLength; n > 0; n-- {
+ rank[n-1].base += rank[n].base
+ }
+ for n := range rank[:maxBitLength] {
+ rank[n].current = rank[n].base
+ }
+ for n, c := range s.count[:s.symbolLen] {
+ r := (highBit32(c+1) + 1) & 31
+ pos := rank[r].current
+ rank[r].current++
+ prev := nodes[(pos-1)&huffNodesMask]
+ for pos > rank[r].base && c > prev.count {
+ nodes[pos&huffNodesMask] = prev
+ pos--
+ prev = nodes[(pos-1)&huffNodesMask]
+ }
+ nodes[pos&huffNodesMask] = nodeElt{count: c, symbol: byte(n)}
+ }
+}
+
+func (s *Scratch) setMaxHeight(lastNonNull int) uint8 {
+ maxNbBits := s.actualTableLog
+ huffNode := s.nodes[1 : huffNodesLen+1]
+ //huffNode = huffNode[: huffNodesLen]
+
+ largestBits := huffNode[lastNonNull].nbBits
+
+ // early exit : no elt > maxNbBits
+ if largestBits <= maxNbBits {
+ return largestBits
+ }
+ totalCost := int(0)
+ baseCost := int(1) << (largestBits - maxNbBits)
+ n := uint32(lastNonNull)
+
+ for huffNode[n].nbBits > maxNbBits {
+ totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits))
+ huffNode[n].nbBits = maxNbBits
+ n--
+ }
+ // n stops at huffNode[n].nbBits <= maxNbBits
+
+ for huffNode[n].nbBits == maxNbBits {
+ n--
+ }
+ // n end at index of smallest symbol using < maxNbBits
+
+ // renorm totalCost
+ totalCost >>= largestBits - maxNbBits /* note : totalCost is necessarily a multiple of baseCost */
+
+ // repay normalized cost
+ {
+ const noSymbol = 0xF0F0F0F0
+ var rankLast [tableLogMax + 2]uint32
+
+ for i := range rankLast[:] {
+ rankLast[i] = noSymbol
+ }
+
+ // Get pos of last (smallest) symbol per rank
+ {
+ currentNbBits := maxNbBits
+ for pos := int(n); pos >= 0; pos-- {
+ if huffNode[pos].nbBits >= currentNbBits {
+ continue
+ }
+ currentNbBits = huffNode[pos].nbBits // < maxNbBits
+ rankLast[maxNbBits-currentNbBits] = uint32(pos)
+ }
+ }
+
+ for totalCost > 0 {
+ nBitsToDecrease := uint8(highBit32(uint32(totalCost))) + 1
+
+ for ; nBitsToDecrease > 1; nBitsToDecrease-- {
+ highPos := rankLast[nBitsToDecrease]
+ lowPos := rankLast[nBitsToDecrease-1]
+ if highPos == noSymbol {
+ continue
+ }
+ if lowPos == noSymbol {
+ break
+ }
+ highTotal := huffNode[highPos].count
+ lowTotal := 2 * huffNode[lowPos].count
+ if highTotal <= lowTotal {
+ break
+ }
+ }
+ // only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !)
+ // HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary
+ // FIXME: try to remove
+ for (nBitsToDecrease <= tableLogMax) && (rankLast[nBitsToDecrease] == noSymbol) {
+ nBitsToDecrease++
+ }
+ totalCost -= 1 << (nBitsToDecrease - 1)
+ if rankLast[nBitsToDecrease-1] == noSymbol {
+ // this rank is no longer empty
+ rankLast[nBitsToDecrease-1] = rankLast[nBitsToDecrease]
+ }
+ huffNode[rankLast[nBitsToDecrease]].nbBits++
+ if rankLast[nBitsToDecrease] == 0 {
+ /* special case, reached largest symbol */
+ rankLast[nBitsToDecrease] = noSymbol
+ } else {
+ rankLast[nBitsToDecrease]--
+ if huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits-nBitsToDecrease {
+ rankLast[nBitsToDecrease] = noSymbol /* this rank is now empty */
+ }
+ }
+ }
+
+ for totalCost < 0 { /* Sometimes, cost correction overshoot */
+ if rankLast[1] == noSymbol { /* special case : no rank 1 symbol (using maxNbBits-1); let's create one from largest rank 0 (using maxNbBits) */
+ for huffNode[n].nbBits == maxNbBits {
+ n--
+ }
+ huffNode[n+1].nbBits--
+ rankLast[1] = n + 1
+ totalCost++
+ continue
+ }
+ huffNode[rankLast[1]+1].nbBits--
+ rankLast[1]++
+ totalCost++
+ }
+ }
+ return maxNbBits
+}
+
+type nodeElt struct {
+ count uint32
+ parent uint16
+ symbol byte
+ nbBits uint8
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 13:42:28 +0000