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huff0: Faster 1X Decompression #435

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merged 3 commits into from Sep 2, 2021
Merged

huff0: Faster 1X Decompression #435

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491e51e
huff0: Faster decompression
klauspost Sep 2, 2021
0046fa2
Combine shifts in 4X
klauspost Sep 2, 2021
e7f5e41
Revert "Combine shifts in 4X"
klauspost Sep 2, 2021
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275 changes: 241 additions & 34 deletions huff0/decompress.go
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Expand Up @@ -344,35 +344,241 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {
var buf [256]byte
var off uint8

shift := (8 - d.actualTableLog) & 7

//fmt.Printf("mask: %b, tl:%d\n", mask, d.actualTableLog)
for br.off >= 4 {
br.fillFast()
v := dt[br.peekByteFast()>>shift]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[br.peekByteFast()>>shift]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[br.peekByteFast()>>shift]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[br.peekByteFast()>>shift]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
switch d.actualTableLog {
case 8:
const shift = 8 - 8
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 7:
const shift = 8 - 7
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 6:
const shift = 8 - 6
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 5:
const shift = 8 - 5
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 4:
const shift = 8 - 4
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 3:
const shift = 8 - 3
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 2:
const shift = 8 - 2
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
}
case 1:
const shift = 8 - 1
for br.off >= 4 {
br.fillFast()
v := dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[uint8(br.value>>(56+shift))]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

off += 4
if off == 0 {
if len(dst)+256 > maxDecodedSize {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
dst = append(dst, buf[:]...)
}
dst = append(dst, buf[:]...)
}
default:
return nil, fmt.Errorf("invalid tablelog: %d", d.actualTableLog)
}

if len(dst)+int(off) > maxDecodedSize {
Expand All @@ -383,6 +589,8 @@ func (d *Decoder) decompress1X8Bit(dst, src []byte) ([]byte, error) {

// br < 4, so uint8 is fine
bitsLeft := int8(uint8(br.off)*8 + (64 - br.bitsRead))
shift := (8 - d.actualTableLog) & 7

for bitsLeft > 0 {
if br.bitsRead >= 64-8 {
for br.off > 0 {
Expand Down Expand Up @@ -423,24 +631,24 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
var buf [256]byte
var off uint8

const shift = 0
const shift = 56

//fmt.Printf("mask: %b, tl:%d\n", mask, d.actualTableLog)
for br.off >= 4 {
br.fillFast()
v := dt[br.peekByteFast()>>shift]
v := dt[uint8(br.value>>shift)]
br.advance(uint8(v.entry))
buf[off+0] = uint8(v.entry >> 8)

v = dt[br.peekByteFast()>>shift]
v = dt[uint8(br.value>>shift)]
br.advance(uint8(v.entry))
buf[off+1] = uint8(v.entry >> 8)

v = dt[br.peekByteFast()>>shift]
v = dt[uint8(br.value>>shift)]
br.advance(uint8(v.entry))
buf[off+2] = uint8(v.entry >> 8)

v = dt[br.peekByteFast()>>shift]
v = dt[uint8(br.value>>shift)]
br.advance(uint8(v.entry))
buf[off+3] = uint8(v.entry >> 8)

Expand Down Expand Up @@ -474,7 +682,7 @@ func (d *Decoder) decompress1X8BitExactly(dst, src []byte) ([]byte, error) {
br.close()
return nil, ErrMaxDecodedSizeExceeded
}
v := dt[br.peekByteFast()>>shift]
v := dt[br.peekByteFast()]
nBits := uint8(v.entry)
br.advance(nBits)
bitsLeft -= int8(nBits)
Expand Down Expand Up @@ -709,7 +917,6 @@ func (d *Decoder) decompress4X8bit(dst, src []byte) ([]byte, error) {
shift := (8 - d.actualTableLog) & 7

const tlSize = 1 << 8
const tlMask = tlSize - 1
single := d.dt.single[:tlSize]

// Use temp table to avoid bound checks/append penalty.
Expand Down