zstd: Improve block encoding speed

zstd/bitwriter.go

@@ -38,14 +38,34 @@ func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
  b.nBits += bits
 }
 
-// addBits32NC will add up to 32 bits.
+// addBits32NC will add up to 31 bits.
 // It will not check if there is space for them,
 // so the caller must ensure that it has flushed recently.
 func (b *bitWriter) addBits32NC(value uint32, bits uint8) {
  b.bitContainer |= uint64(value&bitMask32[bits&31]) << (b.nBits & 63)
  b.nBits += bits
 }
 
+// addBits64NC will add up to 64 bits.
+// There must be space for 32 bits.
+func (b *bitWriter) addBits64NC(value uint64, bits uint8) {
+ if bits <= 31 {
+ b.addBits32Clean(uint32(value), bits)
+ return
+ }
+ b.addBits32Clean(uint32(value), 32)
+ b.flush32()
+ b.addBits32Clean(uint32(value>>32), bits-32)
+}
+
+// addBits32Clean will add up to 32 bits.
+// It will not check if there is space for them.
+// The input must not contain more bits than specified.
+func (b *bitWriter) addBits32Clean(value uint32, bits uint8) {
+ b.bitContainer |= uint64(value) << (b.nBits & 63)
+ b.nBits += bits
+}
+
 // addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
 // It will not check if there is space for them, so the caller must ensure that it has flushed recently.
 func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {

zstd/blockenc.go

@@ -722,52 +722,53 @@ func (b *blockEnc) encode(org []byte, raw, rawAllLits bool) error {
  println("Encoded seq", seq, s, "codes:", s.llCode, s.mlCode, s.ofCode, "states:", ll.state, ml.state, of.state, "bits:", llB, mlB, ofB)
  }
  seq--
- if llEnc.maxBits+mlEnc.maxBits+ofEnc.maxBits <= 32 {
- // No need to flush (common)
- for seq >= 0 {
- s = b.sequences[seq]
- wr.flush32()
- llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
- // tabelog max is 8 for all.
- of.encode(ofB)
- ml.encode(mlB)
- ll.encode(llB)
- wr.flush32()
-
- // We checked that all can stay within 32 bits
- wr.addBits32NC(s.litLen, llB.outBits)
- wr.addBits32NC(s.matchLen, mlB.outBits)
- wr.addBits32NC(s.offset, ofB.outBits)
-
- if debugSequences {
- println("Encoded seq", seq, s)
- }
-
- seq--
- }
- } else {
- for seq >= 0 {
- s = b.sequences[seq]
- wr.flush32()
- llB, ofB, mlB := llTT[s.llCode], ofTT[s.ofCode], mlTT[s.mlCode]
- // tabelog max is below 8 for each.
- of.encode(ofB)
- ml.encode(mlB)
- ll.encode(llB)
- wr.flush32()
-
- // ml+ll = max 32 bits total
- wr.addBits32NC(s.litLen, llB.outBits)
- wr.addBits32NC(s.matchLen, mlB.outBits)
- wr.flush32()
- wr.addBits32NC(s.offset, ofB.outBits)
-
- if debugSequences {
- println("Encoded seq", seq, s)
- }
-
- seq--
- }
+ // Store sequences in reverse...
+ for seq >= 0 {
+ s = b.sequences[seq]
+
+ ofB := ofTT[s.ofCode]
+ wr.flush32() // tablelog max is below 8 for each, so it will fill max 24 bits.
+ //of.encode(ofB)
+ nbBitsOut := (uint32(of.state) + ofB.deltaNbBits) >> 16
+ dstState := int32(of.state>>(nbBitsOut&15)) + int32(ofB.deltaFindState)
+ wr.addBits16NC(of.state, uint8(nbBitsOut))
+ of.state = of.stateTable[dstState]
+
+ // Accumulate extra bits.
+ outBits := ofB.outBits & 31
+ extraBits := uint64(s.offset & bitMask32[outBits])
+ extraBitsN := outBits
+
+ mlB := mlTT[s.mlCode]
+ //ml.encode(mlB)
+ nbBitsOut = (uint32(ml.state) + mlB.deltaNbBits) >> 16
+ dstState = int32(ml.state>>(nbBitsOut&15)) + int32(mlB.deltaFindState)
+ wr.addBits16NC(ml.state, uint8(nbBitsOut))
+ ml.state = ml.stateTable[dstState]
+
+ outBits = mlB.outBits & 31
+ extraBits = extraBits<<outBits | uint64(s.matchLen&bitMask32[outBits])
+ extraBitsN += outBits
+
+ llB := llTT[s.llCode]
+ //ll.encode(llB)
+ nbBitsOut = (uint32(ll.state) + llB.deltaNbBits) >> 16
+ dstState = int32(ll.state>>(nbBitsOut&15)) + int32(llB.deltaFindState)
+ wr.addBits16NC(ll.state, uint8(nbBitsOut))
+ ll.state = ll.stateTable[dstState]
+
+ outBits = llB.outBits & 31
+ extraBits = extraBits<<outBits | uint64(s.litLen&bitMask32[outBits])
+ extraBitsN += outBits
+
+ wr.flush32()
+ wr.addBits64NC(extraBits, extraBitsN)
+
+ if debugSequences {
+ println("Encoded seq", seq, s)
+ }
+
+ seq--
  }
  ml.flush(mlEnc.actualTableLog)
  of.flush(ofEnc.actualTableLog)
@@ -820,7 +821,8 @@ func (b *blockEnc) genCodes() {
  }
 
  var llMax, ofMax, mlMax uint8
- for i, seq := range b.sequences {
+ for i := range b.sequences {
+ seq := &b.sequences[i]
  v := llCode(seq.litLen)
  seq.llCode = v
  llH[v]++
@@ -844,7 +846,6 @@ func (b *blockEnc) genCodes() {
  panic(fmt.Errorf("mlMax > maxMatchLengthSymbol (%d), matchlen: %d", mlMax, seq.matchLen))
  }
  }
- b.sequences[i] = seq
  }
  maxCount := func(a []uint32) int {
  var max uint32