switch to packaged lzma package

2026-05-30 04:20:53 +00:00 · 2018-06-22 11:58:10 -04:00
parent 9000446663
commit 7dfc12d138
19 changed files with 4 additions and 4 deletions
@@ -0,0 +1,128 @@
+// Copyright (c) 2010, Andrei Vieru. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lzma
+
+type litSubCoder struct {
+	coders []uint16
+}
+
+func newLitSubCoder() *litSubCoder {
+	return &litSubCoder{
+		coders: initBitModels(0x300),
+	}
+}
+
+
+func (lsc *litSubCoder) decodeNormal(rd *rangeDecoder) byte {
+	symbol := uint32(1)
+	for symbol < 0x100 {
+		i := rd.decodeBit(lsc.coders, symbol)
+		symbol = symbol<<1 | i
+	}
+	return byte(symbol)
+}
+
+func (lsc *litSubCoder) decodeWithMatchByte(rd *rangeDecoder, matchByte byte) byte {
+	uMatchByte := uint32(matchByte)
+	symbol := uint32(1)
+	for symbol < 0x100 {
+		matchBit := (uMatchByte >> 7) & 1
+		uMatchByte <<= 1
+		bit := rd.decodeBit(lsc.coders, ((1+matchBit)<<8)+symbol)
+		symbol = (symbol << 1) | bit
+		if matchBit != bit {
+			for symbol < 0x100 {
+				i := rd.decodeBit(lsc.coders, symbol)
+				symbol = (symbol << 1) | i
+			}
+			break
+		}
+	}
+	return byte(symbol)
+}
+
+
+func (lsc *litSubCoder) encode(re *rangeEncoder, symbol byte) {
+	uSymbol := uint32(symbol)
+	context := uint32(1)
+	for i := uint32(7); int32(i) >= 0; i-- {
+		bit := (uSymbol >> i) & 1
+		re.encode(lsc.coders, context, bit)
+		context = context<<1 | bit
+	}
+}
+
+func (lsc *litSubCoder) encodeMatched(re *rangeEncoder, matchByte, symbol byte) {
+	uMatchByte := uint32(matchByte)
+	uSymbol := uint32(symbol)
+	context := uint32(1)
+	same := true
+	for i := uint32(7); int32(i) >= 0; i-- {
+		bit := (uSymbol >> i) & 1
+		state := context
+		if same == true {
+			matchBit := (uMatchByte >> i) & 1
+			state += (1 + matchBit) << 8
+			same = false
+			if matchBit == bit {
+				same = true
+			}
+		}
+		re.encode(lsc.coders, state, bit)
+		context = context<<1 | bit
+	}
+}
+
+func (lsc *litSubCoder) getPrice(matchMode bool, matchByte, symbol byte) uint32 {
+	uMatchByte := uint32(matchByte)
+	uSymbol := uint32(symbol)
+	price := uint32(0)
+	context := uint32(1)
+	i := uint32(7)
+	if matchMode == true {
+		for ; int32(i) >= 0; i-- {
+			matchBit := (uMatchByte >> i) & 1
+			bit := (uSymbol >> i) & 1
+			price += getPrice(lsc.coders[(1+matchBit)<<8+context], bit)
+			context = context<<1 | bit
+			if matchBit != bit {
+				i--
+				break
+			}
+		}
+	}
+	for ; int32(i) >= 0; i-- {
+		bit := (uSymbol >> i) & 1
+		price += getPrice(lsc.coders[context], bit)
+		context = context<<1 | bit
+	}
+	return price
+}
+
+
+type litCoder struct {
+	coders      []*litSubCoder
+	numPrevBits uint32 // literal context bits // lc
+	// numPosBits  uint32 // literal position state bits // lp
+	posMask uint32
+}
+
+func newLitCoder(numPosBits, numPrevBits uint32) *litCoder {
+	numStates := uint32(1) << (numPrevBits + numPosBits)
+	lc := &litCoder{
+		coders:      make([]*litSubCoder, numStates),
+		numPrevBits: numPrevBits,
+		// numPosBits:  numPosBits,
+		posMask: (1 << numPosBits) - 1,
+	}
+	for i := uint32(0); i < numStates; i++ {
+		lc.coders[i] = newLitSubCoder()
+	}
+	return lc
+}
+
+func (lc *litCoder) getSubCoder(pos uint32, prevByte byte) *litSubCoder {
+	return lc.coders[((pos&lc.posMask)<<lc.numPrevBits)+uint32(prevByte>>(8-lc.numPrevBits))]
+}