[VOL-4291] Rw-core updates for gRPC migration
Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/klauspost/compress/zstd/fse_decoder.go b/vendor/github.com/klauspost/compress/zstd/fse_decoder.go
new file mode 100644
index 0000000..e6d3d49
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/zstd/fse_decoder.go
@@ -0,0 +1,385 @@
+// 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.
+
+package zstd
+
+import (
+ "errors"
+ "fmt"
+)
+
+const (
+ tablelogAbsoluteMax = 9
+)
+
+const (
+ /*!MEMORY_USAGE :
+ * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
+ * Increasing memory usage improves compression ratio
+ * Reduced memory usage can improve speed, due to cache effect
+ * Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
+ maxMemoryUsage = tablelogAbsoluteMax + 2
+
+ maxTableLog = maxMemoryUsage - 2
+ maxTablesize = 1 << maxTableLog
+ maxTableMask = (1 << maxTableLog) - 1
+ minTablelog = 5
+ maxSymbolValue = 255
+)
+
+// fseDecoder provides temporary storage for compression and decompression.
+type fseDecoder struct {
+ dt [maxTablesize]decSymbol // Decompression table.
+ symbolLen uint16 // Length of active part of the symbol table.
+ actualTableLog uint8 // Selected tablelog.
+ maxBits uint8 // Maximum number of additional bits
+
+ // used for table creation to avoid allocations.
+ stateTable [256]uint16
+ norm [maxSymbolValue + 1]int16
+ preDefined bool
+}
+
+// tableStep returns the next table index.
+func tableStep(tableSize uint32) uint32 {
+ return (tableSize >> 1) + (tableSize >> 3) + 3
+}
+
+// readNCount will read the symbol distribution so decoding tables can be constructed.
+func (s *fseDecoder) readNCount(b *byteReader, maxSymbol uint16) error {
+ var (
+ charnum uint16
+ previous0 bool
+ )
+ if b.remain() < 4 {
+ return errors.New("input too small")
+ }
+ bitStream := b.Uint32NC()
+ nbBits := uint((bitStream & 0xF) + minTablelog) // extract tableLog
+ if nbBits > tablelogAbsoluteMax {
+ println("Invalid tablelog:", nbBits)
+ return errors.New("tableLog too large")
+ }
+ bitStream >>= 4
+ bitCount := uint(4)
+
+ s.actualTableLog = uint8(nbBits)
+ remaining := int32((1 << nbBits) + 1)
+ threshold := int32(1 << nbBits)
+ gotTotal := int32(0)
+ nbBits++
+
+ for remaining > 1 && charnum <= maxSymbol {
+ if previous0 {
+ //println("prev0")
+ n0 := charnum
+ for (bitStream & 0xFFFF) == 0xFFFF {
+ //println("24 x 0")
+ n0 += 24
+ if r := b.remain(); r > 5 {
+ b.advance(2)
+ // The check above should make sure we can read 32 bits
+ bitStream = b.Uint32NC() >> bitCount
+ } else {
+ // end of bit stream
+ bitStream >>= 16
+ bitCount += 16
+ }
+ }
+ //printf("bitstream: %d, 0b%b", bitStream&3, bitStream)
+ for (bitStream & 3) == 3 {
+ n0 += 3
+ bitStream >>= 2
+ bitCount += 2
+ }
+ n0 += uint16(bitStream & 3)
+ bitCount += 2
+
+ if n0 > maxSymbolValue {
+ return errors.New("maxSymbolValue too small")
+ }
+ //println("inserting ", n0-charnum, "zeroes from idx", charnum, "ending before", n0)
+ for charnum < n0 {
+ s.norm[uint8(charnum)] = 0
+ charnum++
+ }
+
+ if r := b.remain(); r >= 7 || r-int(bitCount>>3) >= 4 {
+ b.advance(bitCount >> 3)
+ bitCount &= 7
+ // The check above should make sure we can read 32 bits
+ bitStream = b.Uint32NC() >> bitCount
+ } else {
+ bitStream >>= 2
+ }
+ }
+
+ max := (2*threshold - 1) - remaining
+ var count int32
+
+ if int32(bitStream)&(threshold-1) < max {
+ count = int32(bitStream) & (threshold - 1)
+ if debugAsserts && nbBits < 1 {
+ panic("nbBits underflow")
+ }
+ bitCount += nbBits - 1
+ } else {
+ count = int32(bitStream) & (2*threshold - 1)
+ if count >= threshold {
+ count -= max
+ }
+ bitCount += nbBits
+ }
+
+ // extra accuracy
+ count--
+ if count < 0 {
+ // -1 means +1
+ remaining += count
+ gotTotal -= count
+ } else {
+ remaining -= count
+ gotTotal += count
+ }
+ s.norm[charnum&0xff] = int16(count)
+ charnum++
+ previous0 = count == 0
+ for remaining < threshold {
+ nbBits--
+ threshold >>= 1
+ }
+
+ if r := b.remain(); r >= 7 || r-int(bitCount>>3) >= 4 {
+ b.advance(bitCount >> 3)
+ bitCount &= 7
+ // The check above should make sure we can read 32 bits
+ bitStream = b.Uint32NC() >> (bitCount & 31)
+ } else {
+ bitCount -= (uint)(8 * (len(b.b) - 4 - b.off))
+ b.off = len(b.b) - 4
+ bitStream = b.Uint32() >> (bitCount & 31)
+ }
+ }
+ s.symbolLen = charnum
+ if s.symbolLen <= 1 {
+ return fmt.Errorf("symbolLen (%d) too small", s.symbolLen)
+ }
+ if s.symbolLen > maxSymbolValue+1 {
+ return fmt.Errorf("symbolLen (%d) too big", s.symbolLen)
+ }
+ if remaining != 1 {
+ return fmt.Errorf("corruption detected (remaining %d != 1)", remaining)
+ }
+ if bitCount > 32 {
+ return fmt.Errorf("corruption detected (bitCount %d > 32)", bitCount)
+ }
+ if gotTotal != 1<<s.actualTableLog {
+ return fmt.Errorf("corruption detected (total %d != %d)", gotTotal, 1<<s.actualTableLog)
+ }
+ b.advance((bitCount + 7) >> 3)
+ // println(s.norm[:s.symbolLen], s.symbolLen)
+ return s.buildDtable()
+}
+
+// decSymbol contains information about a state entry,
+// Including the state offset base, the output symbol and
+// the number of bits to read for the low part of the destination state.
+// Using a composite uint64 is faster than a struct with separate members.
+type decSymbol uint64
+
+func newDecSymbol(nbits, addBits uint8, newState uint16, baseline uint32) decSymbol {
+ return decSymbol(nbits) | (decSymbol(addBits) << 8) | (decSymbol(newState) << 16) | (decSymbol(baseline) << 32)
+}
+
+func (d decSymbol) nbBits() uint8 {
+ return uint8(d)
+}
+
+func (d decSymbol) addBits() uint8 {
+ return uint8(d >> 8)
+}
+
+func (d decSymbol) newState() uint16 {
+ return uint16(d >> 16)
+}
+
+func (d decSymbol) baseline() uint32 {
+ return uint32(d >> 32)
+}
+
+func (d decSymbol) baselineInt() int {
+ return int(d >> 32)
+}
+
+func (d *decSymbol) set(nbits, addBits uint8, newState uint16, baseline uint32) {
+ *d = decSymbol(nbits) | (decSymbol(addBits) << 8) | (decSymbol(newState) << 16) | (decSymbol(baseline) << 32)
+}
+
+func (d *decSymbol) setNBits(nBits uint8) {
+ const mask = 0xffffffffffffff00
+ *d = (*d & mask) | decSymbol(nBits)
+}
+
+func (d *decSymbol) setAddBits(addBits uint8) {
+ const mask = 0xffffffffffff00ff
+ *d = (*d & mask) | (decSymbol(addBits) << 8)
+}
+
+func (d *decSymbol) setNewState(state uint16) {
+ const mask = 0xffffffff0000ffff
+ *d = (*d & mask) | decSymbol(state)<<16
+}
+
+func (d *decSymbol) setBaseline(baseline uint32) {
+ const mask = 0xffffffff
+ *d = (*d & mask) | decSymbol(baseline)<<32
+}
+
+func (d *decSymbol) setExt(addBits uint8, baseline uint32) {
+ const mask = 0xffff00ff
+ *d = (*d & mask) | (decSymbol(addBits) << 8) | (decSymbol(baseline) << 32)
+}
+
+// decSymbolValue returns the transformed decSymbol for the given symbol.
+func decSymbolValue(symb uint8, t []baseOffset) (decSymbol, error) {
+ if int(symb) >= len(t) {
+ return 0, fmt.Errorf("rle symbol %d >= max %d", symb, len(t))
+ }
+ lu := t[symb]
+ return newDecSymbol(0, lu.addBits, 0, lu.baseLine), nil
+}
+
+// setRLE will set the decoder til RLE mode.
+func (s *fseDecoder) setRLE(symbol decSymbol) {
+ s.actualTableLog = 0
+ s.maxBits = symbol.addBits()
+ s.dt[0] = symbol
+}
+
+// buildDtable will build the decoding table.
+func (s *fseDecoder) buildDtable() error {
+ tableSize := uint32(1 << s.actualTableLog)
+ highThreshold := tableSize - 1
+ symbolNext := s.stateTable[:256]
+
+ // Init, lay down lowprob symbols
+ {
+ for i, v := range s.norm[:s.symbolLen] {
+ if v == -1 {
+ s.dt[highThreshold].setAddBits(uint8(i))
+ highThreshold--
+ symbolNext[i] = 1
+ } else {
+ symbolNext[i] = uint16(v)
+ }
+ }
+ }
+ // Spread symbols
+ {
+ tableMask := tableSize - 1
+ step := tableStep(tableSize)
+ position := uint32(0)
+ for ss, v := range s.norm[:s.symbolLen] {
+ for i := 0; i < int(v); i++ {
+ s.dt[position].setAddBits(uint8(ss))
+ position = (position + step) & tableMask
+ for position > highThreshold {
+ // lowprob area
+ position = (position + step) & tableMask
+ }
+ }
+ }
+ if position != 0 {
+ // position must reach all cells once, otherwise normalizedCounter is incorrect
+ return errors.New("corrupted input (position != 0)")
+ }
+ }
+
+ // Build Decoding table
+ {
+ tableSize := uint16(1 << s.actualTableLog)
+ for u, v := range s.dt[:tableSize] {
+ symbol := v.addBits()
+ nextState := symbolNext[symbol]
+ symbolNext[symbol] = nextState + 1
+ nBits := s.actualTableLog - byte(highBits(uint32(nextState)))
+ s.dt[u&maxTableMask].setNBits(nBits)
+ newState := (nextState << nBits) - tableSize
+ if newState > tableSize {
+ return fmt.Errorf("newState (%d) outside table size (%d)", newState, tableSize)
+ }
+ if newState == uint16(u) && nBits == 0 {
+ // Seems weird that this is possible with nbits > 0.
+ return fmt.Errorf("newState (%d) == oldState (%d) and no bits", newState, u)
+ }
+ s.dt[u&maxTableMask].setNewState(newState)
+ }
+ }
+ return nil
+}
+
+// transform will transform the decoder table into a table usable for
+// decoding without having to apply the transformation while decoding.
+// The state will contain the base value and the number of bits to read.
+func (s *fseDecoder) transform(t []baseOffset) error {
+ tableSize := uint16(1 << s.actualTableLog)
+ s.maxBits = 0
+ for i, v := range s.dt[:tableSize] {
+ add := v.addBits()
+ if int(add) >= len(t) {
+ return fmt.Errorf("invalid decoding table entry %d, symbol %d >= max (%d)", i, v.addBits(), len(t))
+ }
+ lu := t[add]
+ if lu.addBits > s.maxBits {
+ s.maxBits = lu.addBits
+ }
+ v.setExt(lu.addBits, lu.baseLine)
+ s.dt[i] = v
+ }
+ return nil
+}
+
+type fseState struct {
+ dt []decSymbol
+ state decSymbol
+}
+
+// Initialize and decodeAsync first state and symbol.
+func (s *fseState) init(br *bitReader, tableLog uint8, dt []decSymbol) {
+ s.dt = dt
+ br.fill()
+ s.state = dt[br.getBits(tableLog)]
+}
+
+// next returns the current symbol and sets the next state.
+// At least tablelog bits must be available in the bit reader.
+func (s *fseState) next(br *bitReader) {
+ lowBits := uint16(br.getBits(s.state.nbBits()))
+ s.state = s.dt[s.state.newState()+lowBits]
+}
+
+// finished returns true if all bits have been read from the bitstream
+// and the next state would require reading bits from the input.
+func (s *fseState) finished(br *bitReader) bool {
+ return br.finished() && s.state.nbBits() > 0
+}
+
+// final returns the current state symbol without decoding the next.
+func (s *fseState) final() (int, uint8) {
+ return s.state.baselineInt(), s.state.addBits()
+}
+
+// final returns the current state symbol without decoding the next.
+func (s decSymbol) final() (int, uint8) {
+ return s.baselineInt(), s.addBits()
+}
+
+// nextFast returns the next symbol and sets the next state.
+// This can only be used if no symbols are 0 bits.
+// At least tablelog bits must be available in the bit reader.
+func (s *fseState) nextFast(br *bitReader) (uint32, uint8) {
+ lowBits := uint16(br.getBitsFast(s.state.nbBits()))
+ s.state = s.dt[s.state.newState()+lowBits]
+ return s.state.baseline(), s.state.addBits()
+}