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Performance improvements
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@flanglet
flanglet committed Jan 6, 2024
1 parent ef29239 commit f6df2ca
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Showing 2 changed files with 38 additions and 32 deletions.
63 changes: 31 additions & 32 deletions v2/entropy/ANSRangeCodec.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -334,16 +334,15 @@ func (this *ANSRangeEncoder) Write(block []byte) (int, error) {
return end, nil
}

func (this *ANSRangeEncoder) encodeSymbol(n int, st *int, sym encSymbol) int {
if *st >= sym.xMax {
this.buffer[n] = byte(*st)
this.buffer[n-1] = byte(*st >> 8)
*st >>= 16
func (this *ANSRangeEncoder) encodeSymbol(n int, st int, sym encSymbol) (int, int) {
if st >= sym.xMax {
this.buffer[n] = byte(st)
this.buffer[n-1] = byte(st >> 8)
st >>= 16
n -= 2
}

*st = *st + sym.bias + int((uint64(*st)*sym.invFreq)>>sym.invShift)*sym.cmplFreq
return n
return n, st + sym.bias + int((uint64(st)*sym.invFreq)>>sym.invShift)*sym.cmplFreq
}

func (this *ANSRangeEncoder) encodeChunk(block []byte) {
Expand All @@ -363,10 +362,10 @@ func (this *ANSRangeEncoder) encodeChunk(block []byte) {
symb := this.symbols[0:256]

for i := end4 - 1; i > 0; i -= 4 {
n = this.encodeSymbol(n, &st0, symb[block[i]])
n = this.encodeSymbol(n, &st1, symb[block[i-1]])
n = this.encodeSymbol(n, &st2, symb[block[i-2]])
n = this.encodeSymbol(n, &st3, symb[block[i-3]])
n, st0 = this.encodeSymbol(n, st0, symb[block[i]])
n, st1 = this.encodeSymbol(n, st1, symb[block[i-1]])
n, st2 = this.encodeSymbol(n, st2, symb[block[i-2]])
n, st3 = this.encodeSymbol(n, st3, symb[block[i-3]])
}
} else if len(block) > 1 { // order 1
quarter := end4 >> 2
Expand All @@ -381,13 +380,13 @@ func (this *ANSRangeEncoder) encodeChunk(block []byte) {

for i0 >= 0 {
cur0 := int(block[i0])
n = this.encodeSymbol(n, &st0, this.symbols[(cur0<<8)|prv0])
n, st0 = this.encodeSymbol(n, st0, this.symbols[(cur0<<8)|prv0])
cur1 := int(block[i1])
n = this.encodeSymbol(n, &st1, this.symbols[(cur1<<8)|prv1])
n, st1 = this.encodeSymbol(n, st1, this.symbols[(cur1<<8)|prv1])
cur2 := int(block[i2])
n = this.encodeSymbol(n, &st2, this.symbols[(cur2<<8)|prv2])
n, st2 = this.encodeSymbol(n, st2, this.symbols[(cur2<<8)|prv2])
cur3 := int(block[i3])
n = this.encodeSymbol(n, &st3, this.symbols[(cur3<<8)|prv3])
n, st3 = this.encodeSymbol(n, st3, this.symbols[(cur3<<8)|prv3])
prv0 = cur0
prv1 = cur1
prv2 = cur2
Expand All @@ -399,10 +398,10 @@ func (this *ANSRangeEncoder) encodeChunk(block []byte) {
}

// Last symbols
n = this.encodeSymbol(n, &st0, this.symbols[prv0])
n = this.encodeSymbol(n, &st1, this.symbols[prv1])
n = this.encodeSymbol(n, &st2, this.symbols[prv2])
n = this.encodeSymbol(n, &st3, this.symbols[prv3])
n, st0 = this.encodeSymbol(n, st0, this.symbols[prv0])
n, st1 = this.encodeSymbol(n, st1, this.symbols[prv1])
n, st2 = this.encodeSymbol(n, st2, this.symbols[prv2])
n, st3 = this.encodeSymbol(n, st3, this.symbols[prv3])
}

n++
Expand Down Expand Up @@ -871,18 +870,18 @@ func (this *ANSRangeDecoder) decodeChunkV1(block []byte) {
}
}

func (this *ANSRangeDecoder) decodeSymbol(n int, st *int, sym decSymbol, mask int) int {
func (this *ANSRangeDecoder) decodeSymbol(n int, st int, sym decSymbol, mask int) (int, int) {
// Compute next ANS state
// D(x) = (s, q_s (x/M) + mod(x,M) - b_s) where s is such b_s <= x mod M < b_{s+1}
*st = sym.freq*(*st>>this.logRange) + (*st & mask) - sym.cumFreq
st = sym.freq*(st>>this.logRange) + (st & mask) - sym.cumFreq

// Normalize
if *st < _ANS_TOP {
*st = (*st << 16) | (int(this.buffer[n]) << 8) | int(this.buffer[n+1])
if st < _ANS_TOP {
st = (st << 16) | (int(this.buffer[n]) << 8) | int(this.buffer[n+1])
n += 2
}

return n
return n, st
}

func (this *ANSRangeDecoder) decodeChunkV2(block []byte) {
Expand Down Expand Up @@ -917,16 +916,16 @@ func (this *ANSRangeDecoder) decodeChunkV2(block []byte) {
for i := 0; i < end4; i += 4 {
cur3 := freq2sym[st3&mask]
block[i] = byte(cur3)
n = this.decodeSymbol(n, &st3, symb[cur3], mask)
n, st3 = this.decodeSymbol(n, st3, symb[cur3], mask)
cur2 := freq2sym[st2&mask]
block[i+1] = byte(cur2)
n = this.decodeSymbol(n, &st2, symb[cur2], mask)
n, st2 = this.decodeSymbol(n, st2, symb[cur2], mask)
cur1 := freq2sym[st1&mask]
block[i+2] = byte(cur1)
n = this.decodeSymbol(n, &st1, symb[cur1], mask)
n, st1 = this.decodeSymbol(n, st1, symb[cur1], mask)
cur0 := freq2sym[st0&mask]
block[i+3] = byte(cur0)
n = this.decodeSymbol(n, &st0, symb[cur0], mask)
n, st0 = this.decodeSymbol(n, st0, symb[cur0], mask)
}
} else { // order 1
quarter := end4 >> 2
Expand All @@ -943,16 +942,16 @@ func (this *ANSRangeDecoder) decodeChunkV2(block []byte) {
symbols0 := this.symbols[prv0<<8:]
cur3 := int(this.f2s[(prv3<<this.logRange)+(st3&mask)])
block[i3] = byte(cur3)
n = this.decodeSymbol(n, &st3, symbols3[cur3], mask)
n, st3 = this.decodeSymbol(n, st3, symbols3[cur3], mask)
cur2 := int(this.f2s[(prv2<<this.logRange)+(st2&mask)])
block[i2] = byte(cur2)
n = this.decodeSymbol(n, &st2, symbols2[cur2], mask)
n, st2 = this.decodeSymbol(n, st2, symbols2[cur2], mask)
cur1 := int(this.f2s[(prv1<<this.logRange)+(st1&mask)])
block[i1] = byte(cur1)
n = this.decodeSymbol(n, &st1, symbols1[cur1], mask)
n, st1 = this.decodeSymbol(n, st1, symbols1[cur1], mask)
cur0 := int(this.f2s[(prv0<<this.logRange)+(st0&mask)])
block[i0] = byte(cur0)
n = this.decodeSymbol(n, &st0, symbols0[cur0], mask)
n, st0 = this.decodeSymbol(n, st0, symbols0[cur0], mask)
prv3 = cur3
prv2 = cur2
prv1 = cur1
Expand Down
7 changes: 7 additions & 0 deletions v2/transform/ROLZCodec.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -253,6 +253,13 @@ func (this *rolzCodec1) findMatch(buf []byte, pos int, hash32 uint32, counter in
}
}

if this.posChecks == 0 {
// Ahem terrible hack ...
// This impossible branch improves performance by a few percents
// (due to speculative memory fetch in the other branch probably)
return -1, -1
}

maxMatch -= 4
bestLen := 0
bestIdx := -1
Expand Down

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