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verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.

downloading a git-generated archive based on the 'upstream' tag
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if you have obtained the source via the command 'git clone',
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1 files changed, 506 insertions, 0 deletions

diff --git a/libgo/go/compress/flate/huffman_bit_writer.go b/libgo/go/compress/flate/huffman_bit_writer.go
new file mode 100644
index 000000000..abff82dd6
--- /dev/null
+++ b/libgo/go/compress/flate/huffman_bit_writer.go
@@ -0,0 +1,506 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"io"
+	"math"
+	"os"
+	"strconv"
+)
+
+const (
+	// The largest offset code.
+	offsetCodeCount = 30
+
+	// The largest offset code in the extensions.
+	extendedOffsetCodeCount = 42
+
+	// The special code used to mark the end of a block.
+	endBlockMarker = 256
+
+	// The first length code.
+	lengthCodesStart = 257
+
+	// The number of codegen codes.
+	codegenCodeCount = 19
+	badCode          = 255
+)
+
+// The number of extra bits needed by length code X - LENGTH_CODES_START.
+var lengthExtraBits = []int8{
+	/* 257 */ 0, 0, 0,
+	/* 260 */ 0, 0, 0, 0, 0, 1, 1, 1, 1, 2,
+	/* 270 */ 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
+	/* 280 */ 4, 5, 5, 5, 5, 0,
+}
+
+// The length indicated by length code X - LENGTH_CODES_START.
+var lengthBase = []uint32{
+	0, 1, 2, 3, 4, 5, 6, 7, 8, 10,
+	12, 14, 16, 20, 24, 28, 32, 40, 48, 56,
+	64, 80, 96, 112, 128, 160, 192, 224, 255,
+}
+
+// offset code word extra bits.
+var offsetExtraBits = []int8{
+	0, 0, 0, 0, 1, 1, 2, 2, 3, 3,
+	4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
+	9, 9, 10, 10, 11, 11, 12, 12, 13, 13,
+	/* extended window */
+	14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20,
+}
+
+var offsetBase = []uint32{
+	/* normal deflate */
+	0x000000, 0x000001, 0x000002, 0x000003, 0x000004,
+	0x000006, 0x000008, 0x00000c, 0x000010, 0x000018,
+	0x000020, 0x000030, 0x000040, 0x000060, 0x000080,
+	0x0000c0, 0x000100, 0x000180, 0x000200, 0x000300,
+	0x000400, 0x000600, 0x000800, 0x000c00, 0x001000,
+	0x001800, 0x002000, 0x003000, 0x004000, 0x006000,
+
+	/* extended window */
+	0x008000, 0x00c000, 0x010000, 0x018000, 0x020000,
+	0x030000, 0x040000, 0x060000, 0x080000, 0x0c0000,
+	0x100000, 0x180000, 0x200000, 0x300000,
+}
+
+// The odd order in which the codegen code sizes are written.
+var codegenOrder = []uint32{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+type huffmanBitWriter struct {
+	w io.Writer
+	// Data waiting to be written is bytes[0:nbytes]
+	// and then the low nbits of bits.
+	bits            uint32
+	nbits           uint32
+	bytes           [64]byte
+	nbytes          int
+	literalFreq     []int32
+	offsetFreq      []int32
+	codegen         []uint8
+	codegenFreq     []int32
+	literalEncoding *huffmanEncoder
+	offsetEncoding  *huffmanEncoder
+	codegenEncoding *huffmanEncoder
+	err             os.Error
+}
+
+type WrongValueError struct {
+	name  string
+	from  int32
+	to    int32
+	value int32
+}
+
+func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
+	return &huffmanBitWriter{
+		w:               w,
+		literalFreq:     make([]int32, maxLit),
+		offsetFreq:      make([]int32, extendedOffsetCodeCount),
+		codegen:         make([]uint8, maxLit+extendedOffsetCodeCount+1),
+		codegenFreq:     make([]int32, codegenCodeCount),
+		literalEncoding: newHuffmanEncoder(maxLit),
+		offsetEncoding:  newHuffmanEncoder(extendedOffsetCodeCount),
+		codegenEncoding: newHuffmanEncoder(codegenCodeCount),
+	}
+}
+
+func (err WrongValueError) String() string {
+	return "huffmanBitWriter: " + err.name + " should belong to [" + strconv.Itoa64(int64(err.from)) + ";" +
+		strconv.Itoa64(int64(err.to)) + "] but actual value is " + strconv.Itoa64(int64(err.value))
+}
+
+func (w *huffmanBitWriter) flushBits() {
+	if w.err != nil {
+		w.nbits = 0
+		return
+	}
+	bits := w.bits
+	w.bits >>= 16
+	w.nbits -= 16
+	n := w.nbytes
+	w.bytes[n] = byte(bits)
+	w.bytes[n+1] = byte(bits >> 8)
+	if n += 2; n >= len(w.bytes) {
+		_, w.err = w.w.Write(w.bytes[0:])
+		n = 0
+	}
+	w.nbytes = n
+}
+
+func (w *huffmanBitWriter) flush() {
+	if w.err != nil {
+		w.nbits = 0
+		return
+	}
+	n := w.nbytes
+	if w.nbits > 8 {
+		w.bytes[n] = byte(w.bits)
+		w.bits >>= 8
+		w.nbits -= 8
+		n++
+	}
+	if w.nbits > 0 {
+		w.bytes[n] = byte(w.bits)
+		w.nbits = 0
+		n++
+	}
+	w.bits = 0
+	_, w.err = w.w.Write(w.bytes[0:n])
+	w.nbytes = 0
+}
+
+func (w *huffmanBitWriter) writeBits(b, nb int32) {
+	w.bits |= uint32(b) << w.nbits
+	if w.nbits += uint32(nb); w.nbits >= 16 {
+		w.flushBits()
+	}
+}
+
+func (w *huffmanBitWriter) writeBytes(bytes []byte) {
+	if w.err != nil {
+		return
+	}
+	n := w.nbytes
+	if w.nbits == 8 {
+		w.bytes[n] = byte(w.bits)
+		w.nbits = 0
+		n++
+	}
+	if w.nbits != 0 {
+		w.err = InternalError("writeBytes with unfinished bits")
+		return
+	}
+	if n != 0 {
+		_, w.err = w.w.Write(w.bytes[0:n])
+		if w.err != nil {
+			return
+		}
+	}
+	w.nbytes = 0
+	_, w.err = w.w.Write(bytes)
+}
+
+// RFC 1951 3.2.7 specifies a special run-length encoding for specifiying
+// the literal and offset lengths arrays (which are concatenated into a single
+// array).  This method generates that run-length encoding.
+//
+// The result is written into the codegen array, and the frequencies
+// of each code is written into the codegenFreq array.
+// Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
+// information.  Code badCode is an end marker
+//
+//  numLiterals      The number of literals in literalEncoding
+//  numOffsets       The number of offsets in offsetEncoding
+func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int) {
+	fillInt32s(w.codegenFreq, 0)
+	// Note that we are using codegen both as a temporary variable for holding
+	// a copy of the frequencies, and as the place where we put the result.
+	// This is fine because the output is always shorter than the input used
+	// so far.
+	codegen := w.codegen // cache
+	// Copy the concatenated code sizes to codegen.  Put a marker at the end.
+	copyUint8s(codegen[0:numLiterals], w.literalEncoding.codeBits)
+	copyUint8s(codegen[numLiterals:numLiterals+numOffsets], w.offsetEncoding.codeBits)
+	codegen[numLiterals+numOffsets] = badCode
+
+	size := codegen[0]
+	count := 1
+	outIndex := 0
+	for inIndex := 1; size != badCode; inIndex++ {
+		// INVARIANT: We have seen "count" copies of size that have not yet
+		// had output generated for them.
+		nextSize := codegen[inIndex]
+		if nextSize == size {
+			count++
+			continue
+		}
+		// We need to generate codegen indicating "count" of size.
+		if size != 0 {
+			codegen[outIndex] = size
+			outIndex++
+			w.codegenFreq[size]++
+			count--
+			for count >= 3 {
+				n := min(count, 6)
+				codegen[outIndex] = 16
+				outIndex++
+				codegen[outIndex] = uint8(n - 3)
+				outIndex++
+				w.codegenFreq[16]++
+				count -= n
+			}
+		} else {
+			for count >= 11 {
+				n := min(count, 138)
+				codegen[outIndex] = 18
+				outIndex++
+				codegen[outIndex] = uint8(n - 11)
+				outIndex++
+				w.codegenFreq[18]++
+				count -= n
+			}
+			if count >= 3 {
+				// count >= 3 && count <= 10
+				codegen[outIndex] = 17
+				outIndex++
+				codegen[outIndex] = uint8(count - 3)
+				outIndex++
+				w.codegenFreq[17]++
+				count = 0
+			}
+		}
+		count--
+		for ; count >= 0; count-- {
+			codegen[outIndex] = size
+			outIndex++
+			w.codegenFreq[size]++
+		}
+		// Set up invariant for next time through the loop.
+		size = nextSize
+		count = 1
+	}
+	// Marker indicating the end of the codegen.
+	codegen[outIndex] = badCode
+}
+
+func (w *huffmanBitWriter) writeCode(code *huffmanEncoder, literal uint32) {
+	if w.err != nil {
+		return
+	}
+	w.writeBits(int32(code.code[literal]), int32(code.codeBits[literal]))
+}
+
+// Write the header of a dynamic Huffman block to the output stream.
+//
+//  numLiterals  The number of literals specified in codegen
+//  numOffsets   The number of offsets specified in codegen
+//  numCodegens  Tne number of codegens used in codegen
+func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, numCodegens int, isEof bool) {
+	if w.err != nil {
+		return
+	}
+	var firstBits int32 = 4
+	if isEof {
+		firstBits = 5
+	}
+	w.writeBits(firstBits, 3)
+	w.writeBits(int32(numLiterals-257), 5)
+	if numOffsets > offsetCodeCount {
+		// Extended version of decompressor
+		w.writeBits(int32(offsetCodeCount+((numOffsets-(1+offsetCodeCount))>>3)), 5)
+		w.writeBits(int32((numOffsets-(1+offsetCodeCount))&0x7), 3)
+	} else {
+		w.writeBits(int32(numOffsets-1), 5)
+	}
+	w.writeBits(int32(numCodegens-4), 4)
+
+	for i := 0; i < numCodegens; i++ {
+		value := w.codegenEncoding.codeBits[codegenOrder[i]]
+		w.writeBits(int32(value), 3)
+	}
+
+	i := 0
+	for {
+		var codeWord int = int(w.codegen[i])
+		i++
+		if codeWord == badCode {
+			break
+		}
+		// The low byte contains the actual code to generate.
+		w.writeCode(w.codegenEncoding, uint32(codeWord))
+
+		switch codeWord {
+		case 16:
+			w.writeBits(int32(w.codegen[i]), 2)
+			i++
+			break
+		case 17:
+			w.writeBits(int32(w.codegen[i]), 3)
+			i++
+			break
+		case 18:
+			w.writeBits(int32(w.codegen[i]), 7)
+			i++
+			break
+		}
+	}
+}
+
+func (w *huffmanBitWriter) writeStoredHeader(length int, isEof bool) {
+	if w.err != nil {
+		return
+	}
+	var flag int32
+	if isEof {
+		flag = 1
+	}
+	w.writeBits(flag, 3)
+	w.flush()
+	w.writeBits(int32(length), 16)
+	w.writeBits(int32(^uint16(length)), 16)
+}
+
+func (w *huffmanBitWriter) writeFixedHeader(isEof bool) {
+	if w.err != nil {
+		return
+	}
+	// Indicate that we are a fixed Huffman block
+	var value int32 = 2
+	if isEof {
+		value = 3
+	}
+	w.writeBits(value, 3)
+}
+
+func (w *huffmanBitWriter) writeBlock(tokens []token, eof bool, input []byte) {
+	if w.err != nil {
+		return
+	}
+	fillInt32s(w.literalFreq, 0)
+	fillInt32s(w.offsetFreq, 0)
+
+	n := len(tokens)
+	tokens = tokens[0 : n+1]
+	tokens[n] = endBlockMarker
+
+	totalLength := -1 // Subtract 1 for endBlock.
+	for _, t := range tokens {
+		switch t.typ() {
+		case literalType:
+			w.literalFreq[t.literal()]++
+			totalLength++
+			break
+		case matchType:
+			length := t.length()
+			offset := t.offset()
+			totalLength += int(length + 3)
+			w.literalFreq[lengthCodesStart+lengthCode(length)]++
+			w.offsetFreq[offsetCode(offset)]++
+			break
+		}
+	}
+	w.literalEncoding.generate(w.literalFreq, 15)
+	w.offsetEncoding.generate(w.offsetFreq, 15)
+
+	// get the number of literals
+	numLiterals := len(w.literalFreq)
+	for w.literalFreq[numLiterals-1] == 0 {
+		numLiterals--
+	}
+	// get the number of offsets
+	numOffsets := len(w.offsetFreq)
+	for numOffsets > 1 && w.offsetFreq[numOffsets-1] == 0 {
+		numOffsets--
+	}
+	storedBytes := 0
+	if input != nil {
+		storedBytes = len(input)
+	}
+	var extraBits int64
+	var storedSize int64
+	if storedBytes <= maxStoreBlockSize && input != nil {
+		storedSize = int64((storedBytes + 5) * 8)
+		// We only bother calculating the costs of the extra bits required by
+		// the length of offset fields (which will be the same for both fixed
+		// and dynamic encoding), if we need to compare those two encodings
+		// against stored encoding.
+		for lengthCode := lengthCodesStart + 8; lengthCode < numLiterals; lengthCode++ {
+			// First eight length codes have extra size = 0.
+			extraBits += int64(w.literalFreq[lengthCode]) * int64(lengthExtraBits[lengthCode-lengthCodesStart])
+		}
+		for offsetCode := 4; offsetCode < numOffsets; offsetCode++ {
+			// First four offset codes have extra size = 0.
+			extraBits += int64(w.offsetFreq[offsetCode]) * int64(offsetExtraBits[offsetCode])
+		}
+	} else {
+		storedSize = math.MaxInt32
+	}
+
+	// Figure out which generates smaller code, fixed Huffman, dynamic
+	// Huffman, or just storing the data.
+	var fixedSize int64 = math.MaxInt64
+	if numOffsets <= offsetCodeCount {
+		fixedSize = int64(3) +
+			fixedLiteralEncoding.bitLength(w.literalFreq) +
+			fixedOffsetEncoding.bitLength(w.offsetFreq) +
+			extraBits
+	}
+	// Generate codegen and codegenFrequencies, which indicates how to encode
+	// the literalEncoding and the offsetEncoding.
+	w.generateCodegen(numLiterals, numOffsets)
+	w.codegenEncoding.generate(w.codegenFreq, 7)
+	numCodegens := len(w.codegenFreq)
+	for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
+		numCodegens--
+	}
+	extensionSummand := 0
+	if numOffsets > offsetCodeCount {
+		extensionSummand = 3
+	}
+	dynamicHeader := int64(3+5+5+4+(3*numCodegens)) +
+		// Following line is an extension.
+		int64(extensionSummand) +
+		w.codegenEncoding.bitLength(w.codegenFreq) +
+		int64(extraBits) +
+		int64(w.codegenFreq[16]*2) +
+		int64(w.codegenFreq[17]*3) +
+		int64(w.codegenFreq[18]*7)
+	dynamicSize := dynamicHeader +
+		w.literalEncoding.bitLength(w.literalFreq) +
+		w.offsetEncoding.bitLength(w.offsetFreq)
+
+	if storedSize < fixedSize && storedSize < dynamicSize {
+		w.writeStoredHeader(storedBytes, eof)
+		w.writeBytes(input[0:storedBytes])
+		return
+	}
+	var literalEncoding *huffmanEncoder
+	var offsetEncoding *huffmanEncoder
+
+	if fixedSize <= dynamicSize {
+		w.writeFixedHeader(eof)
+		literalEncoding = fixedLiteralEncoding
+		offsetEncoding = fixedOffsetEncoding
+	} else {
+		// Write the header.
+		w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+		literalEncoding = w.literalEncoding
+		offsetEncoding = w.offsetEncoding
+	}
+
+	// Write the tokens.
+	for _, t := range tokens {
+		switch t.typ() {
+		case literalType:
+			w.writeCode(literalEncoding, t.literal())
+			break
+		case matchType:
+			// Write the length
+			length := t.length()
+			lengthCode := lengthCode(length)
+			w.writeCode(literalEncoding, lengthCode+lengthCodesStart)
+			extraLengthBits := int32(lengthExtraBits[lengthCode])
+			if extraLengthBits > 0 {
+				extraLength := int32(length - lengthBase[lengthCode])
+				w.writeBits(extraLength, extraLengthBits)
+			}
+			// Write the offset
+			offset := t.offset()
+			offsetCode := offsetCode(offset)
+			w.writeCode(offsetEncoding, offsetCode)
+			extraOffsetBits := int32(offsetExtraBits[offsetCode])
+			if extraOffsetBits > 0 {
+				extraOffset := int32(offset - offsetBase[offsetCode])
+				w.writeBits(extraOffset, extraOffsetBits)
+			}
+			break
+		default:
+			panic("unknown token type: " + string(t))
+		}
+	}
+}