diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/flate/level5.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/flate/level5.go | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/level5.go b/vendor/github.com/klauspost/compress/flate/level5.go index 4b97576bd..83ef50ba4 100644 --- a/vendor/github.com/klauspost/compress/flate/level5.go +++ b/vendor/github.com/klauspost/compress/flate/level5.go @@ -12,6 +12,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { const ( inputMargin = 12 - 1 minNonLiteralBlockSize = 1 + 1 + inputMargin + hashShortBytes = 4 ) if debugDeflate && e.cur < 0 { panic(fmt.Sprint("e.cur < 0: ", e.cur)) @@ -88,7 +89,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { var l int32 var t int32 for { - nextHashS := hash4x64(cv, tableBits) + nextHashS := hashLen(cv, tableBits, hashShortBytes) nextHashL := hash7(cv, tableBits) s = nextS @@ -105,7 +106,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { eLong := &e.bTable[nextHashL] eLong.Cur, eLong.Prev = entry, eLong.Cur - nextHashS = hash4x64(next, tableBits) + nextHashS = hashLen(next, tableBits, hashShortBytes) nextHashL = hash7(next, tableBits) t = lCandidate.Cur.offset - e.cur @@ -191,14 +192,21 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { // Try to locate a better match by checking the end of best match... if sAt := s + l; l < 30 && sAt < sLimit { + // Allow some bytes at the beginning to mismatch. + // Sweet spot is 2/3 bytes depending on input. + // 3 is only a little better when it is but sometimes a lot worse. + // The skipped bytes are tested in Extend backwards, + // and still picked up as part of the match if they do. + const skipBeginning = 2 eLong := e.bTable[hash7(load6432(src, sAt), tableBits)].Cur.offset - // Test current - t2 := eLong - e.cur - l - off := s - t2 + t2 := eLong - e.cur - l + skipBeginning + s2 := s + skipBeginning + off := s2 - t2 if t2 >= 0 && off < maxMatchOffset && off > 0 { - if l2 := e.matchlenLong(s, t2, src); l2 > l { + if l2 := e.matchlenLong(s2, t2, src); l2 > l { t = t2 l = l2 + s = s2 } } } @@ -250,7 +258,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { if i < s-1 { cv := load6432(src, i) t := tableEntry{offset: i + e.cur} - e.table[hash4x64(cv, tableBits)] = t + e.table[hashLen(cv, tableBits, hashShortBytes)] = t eLong := &e.bTable[hash7(cv, tableBits)] eLong.Cur, eLong.Prev = t, eLong.Cur @@ -263,7 +271,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { // We only have enough bits for a short entry at i+2 cv >>= 8 t = tableEntry{offset: t.offset + 1} - e.table[hash4x64(cv, tableBits)] = t + e.table[hashLen(cv, tableBits, hashShortBytes)] = t // Skip one - otherwise we risk hitting 's' i += 4 @@ -273,7 +281,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { t2 := tableEntry{offset: t.offset + 1} eLong := &e.bTable[hash7(cv, tableBits)] eLong.Cur, eLong.Prev = t, eLong.Cur - e.table[hash4u(uint32(cv>>8), tableBits)] = t2 + e.table[hashLen(cv>>8, tableBits, hashShortBytes)] = t2 } } } @@ -282,7 +290,7 @@ func (e *fastEncL5) Encode(dst *tokens, src []byte) { // compression we first update the hash table at s-1 and at s. x := load6432(src, s-1) o := e.cur + s - 1 - prevHashS := hash4x64(x, tableBits) + prevHashS := hashLen(x, tableBits, hashShortBytes) prevHashL := hash7(x, tableBits) e.table[prevHashS] = tableEntry{offset: o} eLong := &e.bTable[prevHashL] |