diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/flate/token.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/flate/token.go | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/token.go b/vendor/github.com/klauspost/compress/flate/token.go index f9abf606d..eb862d7a9 100644 --- a/vendor/github.com/klauspost/compress/flate/token.go +++ b/vendor/github.com/klauspost/compress/flate/token.go @@ -13,14 +13,17 @@ import ( ) const ( + // From top // 2 bits: type 0 = literal 1=EOF 2=Match 3=Unused // 8 bits: xlength = length - MIN_MATCH_LENGTH - // 22 bits xoffset = offset - MIN_OFFSET_SIZE, or literal - lengthShift = 22 - offsetMask = 1<<lengthShift - 1 - typeMask = 3 << 30 - literalType = 0 << 30 - matchType = 1 << 30 + // 5 bits offsetcode + // 16 bits xoffset = offset - MIN_OFFSET_SIZE, or literal + lengthShift = 22 + offsetMask = 1<<lengthShift - 1 + typeMask = 3 << 30 + literalType = 0 << 30 + matchType = 1 << 30 + matchOffsetOnlyMask = 0xffff ) // The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH) @@ -187,7 +190,7 @@ func (t *tokens) indexTokens(in []token) { t.AddLiteral(tok.literal()) continue } - t.AddMatch(uint32(tok.length()), tok.offset()) + t.AddMatch(uint32(tok.length()), tok.offset()&matchOffsetOnlyMask) } } @@ -232,7 +235,7 @@ func (t *tokens) EstimatedBits() int { for _, v := range t.litHist[:] { if v > 0 { n := float32(v) - shannon += -mFastLog2(n*invTotal) * n + shannon += atLeastOne(-mFastLog2(n*invTotal)) * n } } // Just add 15 for EOB @@ -240,7 +243,7 @@ func (t *tokens) EstimatedBits() int { for i, v := range t.extraHist[1 : literalCount-256] { if v > 0 { n := float32(v) - shannon += -mFastLog2(n*invTotal) * n + shannon += atLeastOne(-mFastLog2(n*invTotal)) * n bits += int(lengthExtraBits[i&31]) * int(v) nMatches += int(v) } @@ -251,7 +254,7 @@ func (t *tokens) EstimatedBits() int { for i, v := range t.offHist[:offsetCodeCount] { if v > 0 { n := float32(v) - shannon += -mFastLog2(n*invTotal) * n + shannon += atLeastOne(-mFastLog2(n*invTotal)) * n bits += int(offsetExtraBits[i&31]) * int(v) } } @@ -270,11 +273,13 @@ func (t *tokens) AddMatch(xlength uint32, xoffset uint32) { panic(fmt.Errorf("invalid offset: %v", xoffset)) } } + oCode := offsetCode(xoffset) + xoffset |= oCode << 16 t.nLits++ - lengthCode := lengthCodes1[uint8(xlength)] & 31 + + t.extraHist[lengthCodes1[uint8(xlength)]]++ + t.offHist[oCode]++ t.tokens[t.n] = token(matchType | xlength<<lengthShift | xoffset) - t.extraHist[lengthCode]++ - t.offHist[offsetCode(xoffset)&31]++ t.n++ } @@ -286,7 +291,8 @@ func (t *tokens) AddMatchLong(xlength int32, xoffset uint32) { panic(fmt.Errorf("invalid offset: %v", xoffset)) } } - oc := offsetCode(xoffset) & 31 + oc := offsetCode(xoffset) + xoffset |= oc << 16 for xlength > 0 { xl := xlength if xl > 258 { @@ -294,12 +300,11 @@ func (t *tokens) AddMatchLong(xlength int32, xoffset uint32) { xl = 258 - baseMatchLength } xlength -= xl - xl -= 3 + xl -= baseMatchLength t.nLits++ - lengthCode := lengthCodes1[uint8(xl)] & 31 - t.tokens[t.n] = token(matchType | uint32(xl)<<lengthShift | xoffset) - t.extraHist[lengthCode]++ + t.extraHist[lengthCodes1[uint8(xl)]]++ t.offHist[oc]++ + t.tokens[t.n] = token(matchType | uint32(xl)<<lengthShift | xoffset) t.n++ } } |