summaryrefslogtreecommitdiff
path: root/src/pkg/compress/flate
diff options
context:
space:
mode:
Diffstat (limited to 'src/pkg/compress/flate')
-rw-r--r--src/pkg/compress/flate/Makefile17
-rw-r--r--src/pkg/compress/flate/deflate.go493
-rw-r--r--src/pkg/compress/flate/deflate_test.go321
-rw-r--r--src/pkg/compress/flate/flate_test.go139
-rw-r--r--src/pkg/compress/flate/huffman_bit_writer.go494
-rw-r--r--src/pkg/compress/flate/huffman_code.go378
-rw-r--r--src/pkg/compress/flate/inflate.go708
-rw-r--r--src/pkg/compress/flate/reverse_bits.go48
-rw-r--r--src/pkg/compress/flate/token.go103
-rw-r--r--src/pkg/compress/flate/util.go72
10 files changed, 2773 insertions, 0 deletions
diff --git a/src/pkg/compress/flate/Makefile b/src/pkg/compress/flate/Makefile
new file mode 100644
index 000000000..197828a92
--- /dev/null
+++ b/src/pkg/compress/flate/Makefile
@@ -0,0 +1,17 @@
+# 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.
+
+include ../../../Make.inc
+
+TARG=compress/flate
+GOFILES=\
+ deflate.go\
+ huffman_bit_writer.go\
+ huffman_code.go\
+ inflate.go\
+ reverse_bits.go\
+ token.go\
+ util.go\
+
+include ../../../Make.pkg
diff --git a/src/pkg/compress/flate/deflate.go b/src/pkg/compress/flate/deflate.go
new file mode 100644
index 000000000..b1cee0b2f
--- /dev/null
+++ b/src/pkg/compress/flate/deflate.go
@@ -0,0 +1,493 @@
+// 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"
+)
+
+const (
+ NoCompression = 0
+ BestSpeed = 1
+ fastCompression = 3
+ BestCompression = 9
+ DefaultCompression = -1
+ logWindowSize = 15
+ windowSize = 1 << logWindowSize
+ windowMask = windowSize - 1
+ logMaxOffsetSize = 15 // Standard DEFLATE
+ minMatchLength = 3 // The smallest match that the compressor looks for
+ maxMatchLength = 258 // The longest match for the compressor
+ minOffsetSize = 1 // The shortest offset that makes any sence
+
+ // The maximum number of tokens we put into a single flat block, just too
+ // stop things from getting too large.
+ maxFlateBlockTokens = 1 << 14
+ maxStoreBlockSize = 65535
+ hashBits = 15
+ hashSize = 1 << hashBits
+ hashMask = (1 << hashBits) - 1
+ hashShift = (hashBits + minMatchLength - 1) / minMatchLength
+)
+
+type compressionLevel struct {
+ good, lazy, nice, chain, fastSkipHashing int
+}
+
+var levels = []compressionLevel{
+ {}, // 0
+ // For levels 1-3 we don't bother trying with lazy matches
+ {3, 0, 8, 4, 4},
+ {3, 0, 16, 8, 5},
+ {3, 0, 32, 32, 6},
+ // Levels 4-9 use increasingly more lazy matching
+ // and increasingly stringent conditions for "good enough".
+ {4, 4, 16, 16, math.MaxInt32},
+ {8, 16, 32, 32, math.MaxInt32},
+ {8, 16, 128, 128, math.MaxInt32},
+ {8, 32, 128, 256, math.MaxInt32},
+ {32, 128, 258, 1024, math.MaxInt32},
+ {32, 258, 258, 4096, math.MaxInt32},
+}
+
+type compressor struct {
+ compressionLevel
+
+ w *huffmanBitWriter
+
+ // compression algorithm
+ fill func(*compressor, []byte) int // copy data to window
+ step func(*compressor) // process window
+ sync bool // requesting flush
+
+ // Input hash chains
+ // hashHead[hashValue] contains the largest inputIndex with the specified hash value
+ // If hashHead[hashValue] is within the current window, then
+ // hashPrev[hashHead[hashValue] & windowMask] contains the previous index
+ // with the same hash value.
+ chainHead int
+ hashHead []int
+ hashPrev []int
+
+ // input window: unprocessed data is window[index:windowEnd]
+ index int
+ window []byte
+ windowEnd int
+ blockStart int // window index where current tokens start
+ byteAvailable bool // if true, still need to process window[index-1].
+
+ // queued output tokens: tokens[:ti]
+ tokens []token
+ ti int
+
+ // deflate state
+ length int
+ offset int
+ hash int
+ maxInsertIndex int
+ err os.Error
+}
+
+func (d *compressor) fillDeflate(b []byte) int {
+ if d.index >= 2*windowSize-(minMatchLength+maxMatchLength) {
+ // shift the window by windowSize
+ copy(d.window, d.window[windowSize:2*windowSize])
+ d.index -= windowSize
+ d.windowEnd -= windowSize
+ if d.blockStart >= windowSize {
+ d.blockStart -= windowSize
+ } else {
+ d.blockStart = math.MaxInt32
+ }
+ for i, h := range d.hashHead {
+ v := h - windowSize
+ if v < -1 {
+ v = -1
+ }
+ d.hashHead[i] = v
+ }
+ for i, h := range d.hashPrev {
+ v := -h - windowSize
+ if v < -1 {
+ v = -1
+ }
+ d.hashPrev[i] = v
+ }
+ }
+ n := copy(d.window[d.windowEnd:], b)
+ d.windowEnd += n
+ return n
+}
+
+func (d *compressor) writeBlock(tokens []token, index int, eof bool) os.Error {
+ if index > 0 || eof {
+ var window []byte
+ if d.blockStart <= index {
+ window = d.window[d.blockStart:index]
+ }
+ d.blockStart = index
+ d.w.writeBlock(tokens, eof, window)
+ return d.w.err
+ }
+ return nil
+}
+
+// Try to find a match starting at index whose length is greater than prevSize.
+// We only look at chainCount possibilities before giving up.
+func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead int) (length, offset int, ok bool) {
+ minMatchLook := maxMatchLength
+ if lookahead < minMatchLook {
+ minMatchLook = lookahead
+ }
+
+ win := d.window[0 : pos+minMatchLook]
+
+ // We quit when we get a match that's at least nice long
+ nice := len(win) - pos
+ if d.nice < nice {
+ nice = d.nice
+ }
+
+ // If we've got a match that's good enough, only look in 1/4 the chain.
+ tries := d.chain
+ length = prevLength
+ if length >= d.good {
+ tries >>= 2
+ }
+
+ w0 := win[pos]
+ w1 := win[pos+1]
+ wEnd := win[pos+length]
+ minIndex := pos - windowSize
+
+ for i := prevHead; tries > 0; tries-- {
+ if w0 == win[i] && w1 == win[i+1] && wEnd == win[i+length] {
+ // The hash function ensures that if win[i] and win[i+1] match, win[i+2] matches
+
+ n := 3
+ for pos+n < len(win) && win[i+n] == win[pos+n] {
+ n++
+ }
+ if n > length && (n > 3 || pos-i <= 4096) {
+ length = n
+ offset = pos - i
+ ok = true
+ if n >= nice {
+ // The match is good enough that we don't try to find a better one.
+ break
+ }
+ wEnd = win[pos+n]
+ }
+ }
+ if i == minIndex {
+ // hashPrev[i & windowMask] has already been overwritten, so stop now.
+ break
+ }
+ if i = d.hashPrev[i&windowMask]; i < minIndex || i < 0 {
+ break
+ }
+ }
+ return
+}
+
+func (d *compressor) writeStoredBlock(buf []byte) os.Error {
+ if d.w.writeStoredHeader(len(buf), false); d.w.err != nil {
+ return d.w.err
+ }
+ d.w.writeBytes(buf)
+ return d.w.err
+}
+
+func (d *compressor) initDeflate() {
+ d.hashHead = make([]int, hashSize)
+ d.hashPrev = make([]int, windowSize)
+ d.window = make([]byte, 2*windowSize)
+ fillInts(d.hashHead, -1)
+ d.tokens = make([]token, maxFlateBlockTokens, maxFlateBlockTokens+1)
+ d.length = minMatchLength - 1
+ d.offset = 0
+ d.byteAvailable = false
+ d.index = 0
+ d.ti = 0
+ d.hash = 0
+ d.chainHead = -1
+}
+
+func (d *compressor) deflate() {
+ if d.windowEnd-d.index < minMatchLength+maxMatchLength && !d.sync {
+ return
+ }
+
+ d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+ if d.index < d.maxInsertIndex {
+ d.hash = int(d.window[d.index])<<hashShift + int(d.window[d.index+1])
+ }
+
+Loop:
+ for {
+ if d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ lookahead := d.windowEnd - d.index
+ if lookahead < minMatchLength+maxMatchLength {
+ if !d.sync {
+ break Loop
+ }
+ if d.index > d.windowEnd {
+ panic("index > windowEnd")
+ }
+ if lookahead == 0 {
+ // Flush current output block if any.
+ if d.byteAvailable {
+ // There is still one pending token that needs to be flushed
+ d.tokens[d.ti] = literalToken(uint32(d.window[d.index-1]))
+ d.ti++
+ d.byteAvailable = false
+ }
+ if d.ti > 0 {
+ if d.err = d.writeBlock(d.tokens[0:d.ti], d.index, false); d.err != nil {
+ return
+ }
+ d.ti = 0
+ }
+ break Loop
+ }
+ }
+ if d.index < d.maxInsertIndex {
+ // Update the hash
+ d.hash = (d.hash<<hashShift + int(d.window[d.index+2])) & hashMask
+ d.chainHead = d.hashHead[d.hash]
+ d.hashPrev[d.index&windowMask] = d.chainHead
+ d.hashHead[d.hash] = d.index
+ }
+ prevLength := d.length
+ prevOffset := d.offset
+ d.length = minMatchLength - 1
+ d.offset = 0
+ minIndex := d.index - windowSize
+ if minIndex < 0 {
+ minIndex = 0
+ }
+
+ if d.chainHead >= minIndex &&
+ (d.fastSkipHashing != 0 && lookahead > minMatchLength-1 ||
+ d.fastSkipHashing == 0 && lookahead > prevLength && prevLength < d.lazy) {
+ if newLength, newOffset, ok := d.findMatch(d.index, d.chainHead, minMatchLength-1, lookahead); ok {
+ d.length = newLength
+ d.offset = newOffset
+ }
+ }
+ if d.fastSkipHashing != 0 && d.length >= minMatchLength ||
+ d.fastSkipHashing == 0 && prevLength >= minMatchLength && d.length <= prevLength {
+ // There was a match at the previous step, and the current match is
+ // not better. Output the previous match.
+ if d.fastSkipHashing != 0 {
+ d.tokens[d.ti] = matchToken(uint32(d.length-minMatchLength), uint32(d.offset-minOffsetSize))
+ } else {
+ d.tokens[d.ti] = matchToken(uint32(prevLength-minMatchLength), uint32(prevOffset-minOffsetSize))
+ }
+ d.ti++
+ // Insert in the hash table all strings up to the end of the match.
+ // index and index-1 are already inserted. If there is not enough
+ // lookahead, the last two strings are not inserted into the hash
+ // table.
+ if d.length <= d.fastSkipHashing {
+ var newIndex int
+ if d.fastSkipHashing != 0 {
+ newIndex = d.index + d.length
+ } else {
+ newIndex = prevLength - 1
+ }
+ for d.index++; d.index < newIndex; d.index++ {
+ if d.index < d.maxInsertIndex {
+ d.hash = (d.hash<<hashShift + int(d.window[d.index+2])) & hashMask
+ // Get previous value with the same hash.
+ // Our chain should point to the previous value.
+ d.hashPrev[d.index&windowMask] = d.hashHead[d.hash]
+ // Set the head of the hash chain to us.
+ d.hashHead[d.hash] = d.index
+ }
+ }
+ if d.fastSkipHashing == 0 {
+ d.byteAvailable = false
+ d.length = minMatchLength - 1
+ }
+ } else {
+ // For matches this long, we don't bother inserting each individual
+ // item into the table.
+ d.index += d.length
+ d.hash = (int(d.window[d.index])<<hashShift + int(d.window[d.index+1]))
+ }
+ if d.ti == maxFlateBlockTokens {
+ // The block includes the current character
+ if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+ return
+ }
+ d.ti = 0
+ }
+ } else {
+ if d.fastSkipHashing != 0 || d.byteAvailable {
+ i := d.index - 1
+ if d.fastSkipHashing != 0 {
+ i = d.index
+ }
+ d.tokens[d.ti] = literalToken(uint32(d.window[i]))
+ d.ti++
+ if d.ti == maxFlateBlockTokens {
+ if d.err = d.writeBlock(d.tokens, i+1, false); d.err != nil {
+ return
+ }
+ d.ti = 0
+ }
+ }
+ d.index++
+ if d.fastSkipHashing == 0 {
+ d.byteAvailable = true
+ }
+ }
+ }
+}
+
+func (d *compressor) fillStore(b []byte) int {
+ n := copy(d.window[d.windowEnd:], b)
+ d.windowEnd += n
+ return n
+}
+
+func (d *compressor) store() {
+ if d.windowEnd > 0 {
+ d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+ }
+ d.windowEnd = 0
+}
+
+func (d *compressor) write(b []byte) (n int, err os.Error) {
+ n = len(b)
+ b = b[d.fill(d, b):]
+ for len(b) > 0 {
+ d.step(d)
+ b = b[d.fill(d, b):]
+ }
+ return n, d.err
+}
+
+func (d *compressor) syncFlush() os.Error {
+ d.sync = true
+ d.step(d)
+ if d.err == nil {
+ d.w.writeStoredHeader(0, false)
+ d.w.flush()
+ d.err = d.w.err
+ }
+ d.sync = false
+ return d.err
+}
+
+func (d *compressor) init(w io.Writer, level int) (err os.Error) {
+ d.w = newHuffmanBitWriter(w)
+
+ switch {
+ case level == NoCompression:
+ d.window = make([]byte, maxStoreBlockSize)
+ d.fill = (*compressor).fillStore
+ d.step = (*compressor).store
+ case level == DefaultCompression:
+ level = 6
+ fallthrough
+ case 1 <= level && level <= 9:
+ d.compressionLevel = levels[level]
+ d.initDeflate()
+ d.fill = (*compressor).fillDeflate
+ d.step = (*compressor).deflate
+ default:
+ return WrongValueError{"level", 0, 9, int32(level)}
+ }
+ return nil
+}
+
+func (d *compressor) close() os.Error {
+ d.sync = true
+ d.step(d)
+ if d.err != nil {
+ return d.err
+ }
+ if d.w.writeStoredHeader(0, true); d.w.err != nil {
+ return d.w.err
+ }
+ d.w.flush()
+ return d.w.err
+}
+
+// NewWriter returns a new Writer compressing
+// data at the given level. Following zlib, levels
+// range from 1 (BestSpeed) to 9 (BestCompression);
+// higher levels typically run slower but compress more.
+// Level 0 (NoCompression) does not attempt any
+// compression; it only adds the necessary DEFLATE framing.
+func NewWriter(w io.Writer, level int) *Writer {
+ const logWindowSize = logMaxOffsetSize
+ var dw Writer
+ dw.d.init(w, level)
+ return &dw
+}
+
+// NewWriterDict is like NewWriter but initializes the new
+// Writer with a preset dictionary. The returned Writer behaves
+// as if the dictionary had been written to it without producing
+// any compressed output. The compressed data written to w
+// can only be decompressed by a Reader initialized with the
+// same dictionary.
+func NewWriterDict(w io.Writer, level int, dict []byte) *Writer {
+ dw := &dictWriter{w, false}
+ zw := NewWriter(dw, level)
+ zw.Write(dict)
+ zw.Flush()
+ dw.enabled = true
+ return zw
+}
+
+type dictWriter struct {
+ w io.Writer
+ enabled bool
+}
+
+func (w *dictWriter) Write(b []byte) (n int, err os.Error) {
+ if w.enabled {
+ return w.w.Write(b)
+ }
+ return len(b), nil
+}
+
+// A Writer takes data written to it and writes the compressed
+// form of that data to an underlying writer (see NewWriter).
+type Writer struct {
+ d compressor
+}
+
+// Write writes data to w, which will eventually write the
+// compressed form of data to its underlying writer.
+func (w *Writer) Write(data []byte) (n int, err os.Error) {
+ return w.d.write(data)
+}
+
+// Flush flushes any pending compressed data to the underlying writer.
+// It is useful mainly in compressed network protocols, to ensure that
+// a remote reader has enough data to reconstruct a packet.
+// Flush does not return until the data has been written.
+// If the underlying writer returns an error, Flush returns that error.
+//
+// In the terminology of the zlib library, Flush is equivalent to Z_SYNC_FLUSH.
+func (w *Writer) Flush() os.Error {
+ // For more about flushing:
+ // http://www.bolet.org/~pornin/deflate-flush.html
+ return w.d.syncFlush()
+}
+
+// Close flushes and closes the writer.
+func (w *Writer) Close() os.Error {
+ return w.d.close()
+}
diff --git a/src/pkg/compress/flate/deflate_test.go b/src/pkg/compress/flate/deflate_test.go
new file mode 100644
index 000000000..930823685
--- /dev/null
+++ b/src/pkg/compress/flate/deflate_test.go
@@ -0,0 +1,321 @@
+// 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 (
+ "bytes"
+ "fmt"
+ "io"
+ "io/ioutil"
+ "os"
+ "sync"
+ "testing"
+)
+
+type deflateTest struct {
+ in []byte
+ level int
+ out []byte
+}
+
+type deflateInflateTest struct {
+ in []byte
+}
+
+type reverseBitsTest struct {
+ in uint16
+ bitCount uint8
+ out uint16
+}
+
+var deflateTests = []*deflateTest{
+ &deflateTest{[]byte{}, 0, []byte{1, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11}, -1, []byte{18, 4, 4, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11}, DefaultCompression, []byte{18, 4, 4, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11}, 4, []byte{18, 4, 4, 0, 0, 255, 255}},
+
+ &deflateTest{[]byte{0x11}, 0, []byte{0, 1, 0, 254, 255, 17, 1, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11, 0x12}, 0, []byte{0, 2, 0, 253, 255, 17, 18, 1, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 0,
+ []byte{0, 8, 0, 247, 255, 17, 17, 17, 17, 17, 17, 17, 17, 1, 0, 0, 255, 255},
+ },
+ &deflateTest{[]byte{}, 1, []byte{1, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11}, 1, []byte{18, 4, 4, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11, 0x12}, 1, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 1, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
+ &deflateTest{[]byte{}, 9, []byte{1, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11}, 9, []byte{18, 4, 4, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11, 0x12}, 9, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
+ &deflateTest{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 9, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
+}
+
+var deflateInflateTests = []*deflateInflateTest{
+ &deflateInflateTest{[]byte{}},
+ &deflateInflateTest{[]byte{0x11}},
+ &deflateInflateTest{[]byte{0x11, 0x12}},
+ &deflateInflateTest{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}},
+ &deflateInflateTest{[]byte{0x11, 0x10, 0x13, 0x41, 0x21, 0x21, 0x41, 0x13, 0x87, 0x78, 0x13}},
+ &deflateInflateTest{largeDataChunk()},
+}
+
+var reverseBitsTests = []*reverseBitsTest{
+ &reverseBitsTest{1, 1, 1},
+ &reverseBitsTest{1, 2, 2},
+ &reverseBitsTest{1, 3, 4},
+ &reverseBitsTest{1, 4, 8},
+ &reverseBitsTest{1, 5, 16},
+ &reverseBitsTest{17, 5, 17},
+ &reverseBitsTest{257, 9, 257},
+ &reverseBitsTest{29, 5, 23},
+}
+
+func largeDataChunk() []byte {
+ result := make([]byte, 100000)
+ for i := range result {
+ result[i] = byte(i * i & 0xFF)
+ }
+ return result
+}
+
+func TestDeflate(t *testing.T) {
+ for _, h := range deflateTests {
+ var buf bytes.Buffer
+ w := NewWriter(&buf, h.level)
+ w.Write(h.in)
+ w.Close()
+ if !bytes.Equal(buf.Bytes(), h.out) {
+ t.Errorf("Deflate(%d, %x) = %x, want %x", h.level, h.in, buf.Bytes(), h.out)
+ }
+ }
+}
+
+type syncBuffer struct {
+ buf bytes.Buffer
+ mu sync.RWMutex
+ closed bool
+ ready chan bool
+}
+
+func newSyncBuffer() *syncBuffer {
+ return &syncBuffer{ready: make(chan bool, 1)}
+}
+
+func (b *syncBuffer) Read(p []byte) (n int, err os.Error) {
+ for {
+ b.mu.RLock()
+ n, err = b.buf.Read(p)
+ b.mu.RUnlock()
+ if n > 0 || b.closed {
+ return
+ }
+ <-b.ready
+ }
+ panic("unreachable")
+}
+
+func (b *syncBuffer) signal() {
+ select {
+ case b.ready <- true:
+ default:
+ }
+}
+
+func (b *syncBuffer) Write(p []byte) (n int, err os.Error) {
+ n, err = b.buf.Write(p)
+ b.signal()
+ return
+}
+
+func (b *syncBuffer) WriteMode() {
+ b.mu.Lock()
+}
+
+func (b *syncBuffer) ReadMode() {
+ b.mu.Unlock()
+ b.signal()
+}
+
+func (b *syncBuffer) Close() os.Error {
+ b.closed = true
+ b.signal()
+ return nil
+}
+
+func testSync(t *testing.T, level int, input []byte, name string) {
+ if len(input) == 0 {
+ return
+ }
+
+ t.Logf("--testSync %d, %d, %s", level, len(input), name)
+ buf := newSyncBuffer()
+ buf1 := new(bytes.Buffer)
+ buf.WriteMode()
+ w := NewWriter(io.MultiWriter(buf, buf1), level)
+ r := NewReader(buf)
+
+ // Write half the input and read back.
+ for i := 0; i < 2; i++ {
+ var lo, hi int
+ if i == 0 {
+ lo, hi = 0, (len(input)+1)/2
+ } else {
+ lo, hi = (len(input)+1)/2, len(input)
+ }
+ t.Logf("#%d: write %d-%d", i, lo, hi)
+ if _, err := w.Write(input[lo:hi]); err != nil {
+ t.Errorf("testSync: write: %v", err)
+ return
+ }
+ if i == 0 {
+ if err := w.Flush(); err != nil {
+ t.Errorf("testSync: flush: %v", err)
+ return
+ }
+ } else {
+ if err := w.Close(); err != nil {
+ t.Errorf("testSync: close: %v", err)
+ }
+ }
+ buf.ReadMode()
+ out := make([]byte, hi-lo+1)
+ m, err := io.ReadAtLeast(r, out, hi-lo)
+ t.Logf("#%d: read %d", i, m)
+ if m != hi-lo || err != nil {
+ t.Errorf("testSync/%d (%d, %d, %s): read %d: %d, %v (%d left)", i, level, len(input), name, hi-lo, m, err, buf.buf.Len())
+ return
+ }
+ if !bytes.Equal(input[lo:hi], out[:hi-lo]) {
+ t.Errorf("testSync/%d: read wrong bytes: %x vs %x", i, input[lo:hi], out[:hi-lo])
+ return
+ }
+ // This test originally checked that after reading
+ // the first half of the input, there was nothing left
+ // in the read buffer (buf.buf.Len() != 0) but that is
+ // not necessarily the case: the write Flush may emit
+ // some extra framing bits that are not necessary
+ // to process to obtain the first half of the uncompressed
+ // data. The test ran correctly most of the time, because
+ // the background goroutine had usually read even
+ // those extra bits by now, but it's not a useful thing to
+ // check.
+ buf.WriteMode()
+ }
+ buf.ReadMode()
+ out := make([]byte, 10)
+ if n, err := r.Read(out); n > 0 || err != os.EOF {
+ t.Errorf("testSync (%d, %d, %s): final Read: %d, %v (hex: %x)", level, len(input), name, n, err, out[0:n])
+ }
+ if buf.buf.Len() != 0 {
+ t.Errorf("testSync (%d, %d, %s): extra data at end", level, len(input), name)
+ }
+ r.Close()
+
+ // stream should work for ordinary reader too
+ r = NewReader(buf1)
+ out, err := ioutil.ReadAll(r)
+ if err != nil {
+ t.Errorf("testSync: read: %s", err)
+ return
+ }
+ r.Close()
+ if !bytes.Equal(input, out) {
+ t.Errorf("testSync: decompress(compress(data)) != data: level=%d input=%s", level, name)
+ }
+}
+
+func testToFromWithLevel(t *testing.T, level int, input []byte, name string) os.Error {
+ buffer := bytes.NewBuffer(nil)
+ w := NewWriter(buffer, level)
+ w.Write(input)
+ w.Close()
+ r := NewReader(buffer)
+ out, err := ioutil.ReadAll(r)
+ if err != nil {
+ t.Errorf("read: %s", err)
+ return err
+ }
+ r.Close()
+ if !bytes.Equal(input, out) {
+ t.Errorf("decompress(compress(data)) != data: level=%d input=%s", level, name)
+ }
+
+ testSync(t, level, input, name)
+ return nil
+}
+
+func testToFrom(t *testing.T, input []byte, name string) {
+ for i := 0; i < 10; i++ {
+ testToFromWithLevel(t, i, input, name)
+ }
+}
+
+func TestDeflateInflate(t *testing.T) {
+ for i, h := range deflateInflateTests {
+ testToFrom(t, h.in, fmt.Sprintf("#%d", i))
+ }
+}
+
+func TestReverseBits(t *testing.T) {
+ for _, h := range reverseBitsTests {
+ if v := reverseBits(h.in, h.bitCount); v != h.out {
+ t.Errorf("reverseBits(%v,%v) = %v, want %v",
+ h.in, h.bitCount, v, h.out)
+ }
+ }
+}
+
+func TestDeflateInflateString(t *testing.T) {
+ gold, err := ioutil.ReadFile("../testdata/e.txt")
+ if err != nil {
+ t.Error(err)
+ }
+ testToFromWithLevel(t, 1, gold, "2.718281828...")
+}
+
+func TestReaderDict(t *testing.T) {
+ const (
+ dict = "hello world"
+ text = "hello again world"
+ )
+ var b bytes.Buffer
+ w := NewWriter(&b, 5)
+ w.Write([]byte(dict))
+ w.Flush()
+ b.Reset()
+ w.Write([]byte(text))
+ w.Close()
+
+ r := NewReaderDict(&b, []byte(dict))
+ data, err := ioutil.ReadAll(r)
+ if err != nil {
+ t.Fatal(err)
+ }
+ if string(data) != "hello again world" {
+ t.Fatalf("read returned %q want %q", string(data), text)
+ }
+}
+
+func TestWriterDict(t *testing.T) {
+ const (
+ dict = "hello world"
+ text = "hello again world"
+ )
+ var b bytes.Buffer
+ w := NewWriter(&b, 5)
+ w.Write([]byte(dict))
+ w.Flush()
+ b.Reset()
+ w.Write([]byte(text))
+ w.Close()
+
+ var b1 bytes.Buffer
+ w = NewWriterDict(&b1, 5, []byte(dict))
+ w.Write([]byte(text))
+ w.Close()
+
+ if !bytes.Equal(b1.Bytes(), b.Bytes()) {
+ t.Fatalf("writer wrote %q want %q", b1.Bytes(), b.Bytes())
+ }
+}
diff --git a/src/pkg/compress/flate/flate_test.go b/src/pkg/compress/flate/flate_test.go
new file mode 100644
index 000000000..bfd3b8381
--- /dev/null
+++ b/src/pkg/compress/flate/flate_test.go
@@ -0,0 +1,139 @@
+// 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.
+
+// This test tests some internals of the flate package.
+// The tests in package compress/gzip serve as the
+// end-to-end test of the decompressor.
+
+package flate
+
+import (
+ "bytes"
+ "reflect"
+ "testing"
+)
+
+// The Huffman code lengths used by the fixed-format Huffman blocks.
+var fixedHuffmanBits = [...]int{
+ // 0-143 length 8
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+
+ // 144-255 length 9
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+
+ // 256-279 length 7
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7,
+
+ // 280-287 length 8
+ 8, 8, 8, 8, 8, 8, 8, 8,
+}
+
+type InitDecoderTest struct {
+ in []int
+ out huffmanDecoder
+ ok bool
+}
+
+var initDecoderTests = []*InitDecoderTest{
+ // Example from Connell 1973,
+ &InitDecoderTest{
+ []int{3, 5, 2, 4, 3, 5, 5, 4, 4, 3, 4, 5},
+ huffmanDecoder{
+ 2, 5,
+ [maxCodeLen + 1]int{2: 0, 4, 13, 31},
+ [maxCodeLen + 1]int{2: 0, 1, 6, 20},
+ // Paper used different code assignment:
+ // 2, 9, 4, 0, 10, 8, 3, 7, 1, 5, 11, 6
+ // Reordered here so that codes of same length
+ // are assigned to increasing numbers.
+ []int{2, 0, 4, 9, 3, 7, 8, 10, 1, 5, 6, 11},
+ },
+ true,
+ },
+
+ // Example from RFC 1951 section 3.2.2
+ &InitDecoderTest{
+ []int{2, 1, 3, 3},
+ huffmanDecoder{
+ 1, 3,
+ [maxCodeLen + 1]int{1: 0, 2, 7},
+ [maxCodeLen + 1]int{1: 0, 1, 4},
+ []int{1, 0, 2, 3},
+ },
+ true,
+ },
+
+ // Second example from RFC 1951 section 3.2.2
+ &InitDecoderTest{
+ []int{3, 3, 3, 3, 3, 2, 4, 4},
+ huffmanDecoder{
+ 2, 4,
+ [maxCodeLen + 1]int{2: 0, 6, 15},
+ [maxCodeLen + 1]int{2: 0, 1, 8},
+ []int{5, 0, 1, 2, 3, 4, 6, 7},
+ },
+ true,
+ },
+
+ // Static Huffman codes (RFC 1951 section 3.2.6)
+ &InitDecoderTest{
+ fixedHuffmanBits[0:],
+ fixedHuffmanDecoder,
+ true,
+ },
+
+ // Illegal input.
+ &InitDecoderTest{
+ []int{},
+ huffmanDecoder{},
+ false,
+ },
+
+ // Illegal input.
+ &InitDecoderTest{
+ []int{0, 0, 0, 0, 0, 0, 0},
+ huffmanDecoder{},
+ false,
+ },
+}
+
+func TestInitDecoder(t *testing.T) {
+ for i, tt := range initDecoderTests {
+ var h huffmanDecoder
+ if h.init(tt.in) != tt.ok {
+ t.Errorf("test %d: init = %v", i, !tt.ok)
+ continue
+ }
+ if !reflect.DeepEqual(&h, &tt.out) {
+ t.Errorf("test %d:\nhave %v\nwant %v", i, h, tt.out)
+ }
+ }
+}
+
+func TestUncompressedSource(t *testing.T) {
+ decoder := NewReader(bytes.NewBuffer([]byte{0x01, 0x01, 0x00, 0xfe, 0xff, 0x11}))
+ output := make([]byte, 1)
+ n, error := decoder.Read(output)
+ if n != 1 || error != nil {
+ t.Fatalf("decoder.Read() = %d, %v, want 1, nil", n, error)
+ }
+ if output[0] != 0x11 {
+ t.Errorf("output[0] = %x, want 0x11", output[0])
+ }
+}
diff --git a/src/pkg/compress/flate/huffman_bit_writer.go b/src/pkg/compress/flate/huffman_bit_writer.go
new file mode 100644
index 000000000..3981df5cb
--- /dev/null
+++ b/src/pkg/compress/flate/huffman_bit_writer.go
@@ -0,0 +1,494 @@
+// 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 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, offsetCodeCount),
+ codegen: make([]uint8, maxLit+offsetCodeCount+1),
+ codegenFreq: make([]int32, codegenCodeCount),
+ literalEncoding: newHuffmanEncoder(maxLit),
+ offsetEncoding: newHuffmanEncoder(offsetCodeCount),
+ 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 specifying
+// 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 The 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)
+ 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
+
+ for _, t := range tokens {
+ switch t.typ() {
+ case literalType:
+ w.literalFreq[t.literal()]++
+ case matchType:
+ length := t.length()
+ offset := t.offset()
+ w.literalFreq[lengthCodesStart+lengthCode(length)]++
+ w.offsetFreq[offsetCode(offset)]++
+ }
+ }
+
+ // 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 > 0 && w.offsetFreq[numOffsets-1] == 0 {
+ numOffsets--
+ }
+ if numOffsets == 0 {
+ // We haven't found a single match. If we want to go with the dynamic encoding,
+ // we should count at least one offset to be sure that the offset huffman tree could be encoded.
+ w.offsetFreq[0] = 1
+ numOffsets = 1
+ }
+
+ w.literalEncoding.generate(w.literalFreq, 15)
+ w.offsetEncoding.generate(w.offsetFreq, 15)
+
+ storedBytes := 0
+ if input != nil {
+ storedBytes = len(input)
+ }
+ var extraBits int64
+ var storedSize int64 = math.MaxInt64
+ 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])
+ }
+ }
+
+ // Figure out smallest code.
+ // Fixed Huffman baseline.
+ var size = int64(3) +
+ fixedLiteralEncoding.bitLength(w.literalFreq) +
+ fixedOffsetEncoding.bitLength(w.offsetFreq) +
+ extraBits
+ var literalEncoding = fixedLiteralEncoding
+ var offsetEncoding = fixedOffsetEncoding
+
+ // Dynamic Huffman?
+ var numCodegens int
+
+ // 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--
+ }
+ dynamicHeader := int64(3+5+5+4+(3*numCodegens)) +
+ 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 dynamicSize < size {
+ size = dynamicSize
+ literalEncoding = w.literalEncoding
+ offsetEncoding = w.offsetEncoding
+ }
+
+ // Stored bytes?
+ if storedSize < size {
+ w.writeStoredHeader(storedBytes, eof)
+ w.writeBytes(input[0:storedBytes])
+ return
+ }
+
+ // Huffman.
+ if literalEncoding == fixedLiteralEncoding {
+ w.writeFixedHeader(eof)
+ } else {
+ w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+ }
+ 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))
+ }
+ }
+}
diff --git a/src/pkg/compress/flate/huffman_code.go b/src/pkg/compress/flate/huffman_code.go
new file mode 100644
index 000000000..7ed603a4f
--- /dev/null
+++ b/src/pkg/compress/flate/huffman_code.go
@@ -0,0 +1,378 @@
+// 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 (
+ "math"
+ "sort"
+)
+
+type huffmanEncoder struct {
+ codeBits []uint8
+ code []uint16
+}
+
+type literalNode struct {
+ literal uint16
+ freq int32
+}
+
+type chain struct {
+ // The sum of the leaves in this tree
+ freq int32
+
+ // The number of literals to the left of this item at this level
+ leafCount int32
+
+ // The right child of this chain in the previous level.
+ up *chain
+}
+
+type levelInfo struct {
+ // Our level. for better printing
+ level int32
+
+ // The most recent chain generated for this level
+ lastChain *chain
+
+ // The frequency of the next character to add to this level
+ nextCharFreq int32
+
+ // The frequency of the next pair (from level below) to add to this level.
+ // Only valid if the "needed" value of the next lower level is 0.
+ nextPairFreq int32
+
+ // The number of chains remaining to generate for this level before moving
+ // up to the next level
+ needed int32
+
+ // The levelInfo for level+1
+ up *levelInfo
+
+ // The levelInfo for level-1
+ down *levelInfo
+}
+
+func maxNode() literalNode { return literalNode{math.MaxUint16, math.MaxInt32} }
+
+func newHuffmanEncoder(size int) *huffmanEncoder {
+ return &huffmanEncoder{make([]uint8, size), make([]uint16, size)}
+}
+
+// Generates a HuffmanCode corresponding to the fixed literal table
+func generateFixedLiteralEncoding() *huffmanEncoder {
+ h := newHuffmanEncoder(maxLit)
+ codeBits := h.codeBits
+ code := h.code
+ var ch uint16
+ for ch = 0; ch < maxLit; ch++ {
+ var bits uint16
+ var size uint8
+ switch {
+ case ch < 144:
+ // size 8, 000110000 .. 10111111
+ bits = ch + 48
+ size = 8
+ break
+ case ch < 256:
+ // size 9, 110010000 .. 111111111
+ bits = ch + 400 - 144
+ size = 9
+ break
+ case ch < 280:
+ // size 7, 0000000 .. 0010111
+ bits = ch - 256
+ size = 7
+ break
+ default:
+ // size 8, 11000000 .. 11000111
+ bits = ch + 192 - 280
+ size = 8
+ }
+ codeBits[ch] = size
+ code[ch] = reverseBits(bits, size)
+ }
+ return h
+}
+
+func generateFixedOffsetEncoding() *huffmanEncoder {
+ h := newHuffmanEncoder(30)
+ codeBits := h.codeBits
+ code := h.code
+ for ch := uint16(0); ch < 30; ch++ {
+ codeBits[ch] = 5
+ code[ch] = reverseBits(ch, 5)
+ }
+ return h
+}
+
+var fixedLiteralEncoding *huffmanEncoder = generateFixedLiteralEncoding()
+var fixedOffsetEncoding *huffmanEncoder = generateFixedOffsetEncoding()
+
+func (h *huffmanEncoder) bitLength(freq []int32) int64 {
+ var total int64
+ for i, f := range freq {
+ if f != 0 {
+ total += int64(f) * int64(h.codeBits[i])
+ }
+ }
+ return total
+}
+
+// Generate elements in the chain using an iterative algorithm.
+func (h *huffmanEncoder) generateChains(top *levelInfo, list []literalNode) {
+ n := len(list)
+ list = list[0 : n+1]
+ list[n] = maxNode()
+
+ l := top
+ for {
+ if l.nextPairFreq == math.MaxInt32 && l.nextCharFreq == math.MaxInt32 {
+ // We've run out of both leafs and pairs.
+ // End all calculations for this level.
+ // To m sure we never come back to this level or any lower level,
+ // set nextPairFreq impossibly large.
+ l.lastChain = nil
+ l.needed = 0
+ l = l.up
+ l.nextPairFreq = math.MaxInt32
+ continue
+ }
+
+ prevFreq := l.lastChain.freq
+ if l.nextCharFreq < l.nextPairFreq {
+ // The next item on this row is a leaf node.
+ n := l.lastChain.leafCount + 1
+ l.lastChain = &chain{l.nextCharFreq, n, l.lastChain.up}
+ l.nextCharFreq = list[n].freq
+ } else {
+ // The next item on this row is a pair from the previous row.
+ // nextPairFreq isn't valid until we generate two
+ // more values in the level below
+ l.lastChain = &chain{l.nextPairFreq, l.lastChain.leafCount, l.down.lastChain}
+ l.down.needed = 2
+ }
+
+ if l.needed--; l.needed == 0 {
+ // We've done everything we need to do for this level.
+ // Continue calculating one level up. Fill in nextPairFreq
+ // of that level with the sum of the two nodes we've just calculated on
+ // this level.
+ up := l.up
+ if up == nil {
+ // All done!
+ return
+ }
+ up.nextPairFreq = prevFreq + l.lastChain.freq
+ l = up
+ } else {
+ // If we stole from below, move down temporarily to replenish it.
+ for l.down.needed > 0 {
+ l = l.down
+ }
+ }
+ }
+}
+
+// Return the number of literals assigned to each bit size in the Huffman encoding
+//
+// This method is only called when list.length >= 3
+// The cases of 0, 1, and 2 literals are handled by special case code.
+//
+// list An array of the literals with non-zero frequencies
+// and their associated frequencies. The array is in order of increasing
+// frequency, and has as its last element a special element with frequency
+// MaxInt32
+// maxBits The maximum number of bits that should be used to encode any literal.
+// return An integer array in which array[i] indicates the number of literals
+// that should be encoded in i bits.
+func (h *huffmanEncoder) bitCounts(list []literalNode, maxBits int32) []int32 {
+ n := int32(len(list))
+ list = list[0 : n+1]
+ list[n] = maxNode()
+
+ // The tree can't have greater depth than n - 1, no matter what. This
+ // saves a little bit of work in some small cases
+ maxBits = minInt32(maxBits, n-1)
+
+ // Create information about each of the levels.
+ // A bogus "Level 0" whose sole purpose is so that
+ // level1.prev.needed==0. This makes level1.nextPairFreq
+ // be a legitimate value that never gets chosen.
+ top := &levelInfo{needed: 0}
+ chain2 := &chain{list[1].freq, 2, new(chain)}
+ for level := int32(1); level <= maxBits; level++ {
+ // For every level, the first two items are the first two characters.
+ // We initialize the levels as if we had already figured this out.
+ top = &levelInfo{
+ level: level,
+ lastChain: chain2,
+ nextCharFreq: list[2].freq,
+ nextPairFreq: list[0].freq + list[1].freq,
+ down: top,
+ }
+ top.down.up = top
+ if level == 1 {
+ top.nextPairFreq = math.MaxInt32
+ }
+ }
+
+ // We need a total of 2*n - 2 items at top level and have already generated 2.
+ top.needed = 2*n - 4
+
+ l := top
+ for {
+ if l.nextPairFreq == math.MaxInt32 && l.nextCharFreq == math.MaxInt32 {
+ // We've run out of both leafs and pairs.
+ // End all calculations for this level.
+ // To m sure we never come back to this level or any lower level,
+ // set nextPairFreq impossibly large.
+ l.lastChain = nil
+ l.needed = 0
+ l = l.up
+ l.nextPairFreq = math.MaxInt32
+ continue
+ }
+
+ prevFreq := l.lastChain.freq
+ if l.nextCharFreq < l.nextPairFreq {
+ // The next item on this row is a leaf node.
+ n := l.lastChain.leafCount + 1
+ l.lastChain = &chain{l.nextCharFreq, n, l.lastChain.up}
+ l.nextCharFreq = list[n].freq
+ } else {
+ // The next item on this row is a pair from the previous row.
+ // nextPairFreq isn't valid until we generate two
+ // more values in the level below
+ l.lastChain = &chain{l.nextPairFreq, l.lastChain.leafCount, l.down.lastChain}
+ l.down.needed = 2
+ }
+
+ if l.needed--; l.needed == 0 {
+ // We've done everything we need to do for this level.
+ // Continue calculating one level up. Fill in nextPairFreq
+ // of that level with the sum of the two nodes we've just calculated on
+ // this level.
+ up := l.up
+ if up == nil {
+ // All done!
+ break
+ }
+ up.nextPairFreq = prevFreq + l.lastChain.freq
+ l = up
+ } else {
+ // If we stole from below, move down temporarily to replenish it.
+ for l.down.needed > 0 {
+ l = l.down
+ }
+ }
+ }
+
+ // Somethings is wrong if at the end, the top level is null or hasn't used
+ // all of the leaves.
+ if top.lastChain.leafCount != n {
+ panic("top.lastChain.leafCount != n")
+ }
+
+ bitCount := make([]int32, maxBits+1)
+ bits := 1
+ for chain := top.lastChain; chain.up != nil; chain = chain.up {
+ // chain.leafCount gives the number of literals requiring at least "bits"
+ // bits to encode.
+ bitCount[bits] = chain.leafCount - chain.up.leafCount
+ bits++
+ }
+ return bitCount
+}
+
+// Look at the leaves and assign them a bit count and an encoding as specified
+// in RFC 1951 3.2.2
+func (h *huffmanEncoder) assignEncodingAndSize(bitCount []int32, list []literalNode) {
+ code := uint16(0)
+ for n, bits := range bitCount {
+ code <<= 1
+ if n == 0 || bits == 0 {
+ continue
+ }
+ // The literals list[len(list)-bits] .. list[len(list)-bits]
+ // are encoded using "bits" bits, and get the values
+ // code, code + 1, .... The code values are
+ // assigned in literal order (not frequency order).
+ chunk := list[len(list)-int(bits):]
+ sortByLiteral(chunk)
+ for _, node := range chunk {
+ h.codeBits[node.literal] = uint8(n)
+ h.code[node.literal] = reverseBits(code, uint8(n))
+ code++
+ }
+ list = list[0 : len(list)-int(bits)]
+ }
+}
+
+// Update this Huffman Code object to be the minimum code for the specified frequency count.
+//
+// freq An array of frequencies, in which frequency[i] gives the frequency of literal i.
+// maxBits The maximum number of bits to use for any literal.
+func (h *huffmanEncoder) generate(freq []int32, maxBits int32) {
+ list := make([]literalNode, len(freq)+1)
+ // Number of non-zero literals
+ count := 0
+ // Set list to be the set of all non-zero literals and their frequencies
+ for i, f := range freq {
+ if f != 0 {
+ list[count] = literalNode{uint16(i), f}
+ count++
+ } else {
+ h.codeBits[i] = 0
+ }
+ }
+ // If freq[] is shorter than codeBits[], fill rest of codeBits[] with zeros
+ h.codeBits = h.codeBits[0:len(freq)]
+ list = list[0:count]
+ if count <= 2 {
+ // Handle the small cases here, because they are awkward for the general case code. With
+ // two or fewer literals, everything has bit length 1.
+ for i, node := range list {
+ // "list" is in order of increasing literal value.
+ h.codeBits[node.literal] = 1
+ h.code[node.literal] = uint16(i)
+ }
+ return
+ }
+ sortByFreq(list)
+
+ // Get the number of literals for each bit count
+ bitCount := h.bitCounts(list, maxBits)
+ // And do the assignment
+ h.assignEncodingAndSize(bitCount, list)
+}
+
+type literalNodeSorter struct {
+ a []literalNode
+ less func(i, j int) bool
+}
+
+func (s literalNodeSorter) Len() int { return len(s.a) }
+
+func (s literalNodeSorter) Less(i, j int) bool {
+ return s.less(i, j)
+}
+
+func (s literalNodeSorter) Swap(i, j int) { s.a[i], s.a[j] = s.a[j], s.a[i] }
+
+func sortByFreq(a []literalNode) {
+ s := &literalNodeSorter{a, func(i, j int) bool {
+ if a[i].freq == a[j].freq {
+ return a[i].literal < a[j].literal
+ }
+ return a[i].freq < a[j].freq
+ }}
+ sort.Sort(s)
+}
+
+func sortByLiteral(a []literalNode) {
+ s := &literalNodeSorter{a, func(i, j int) bool { return a[i].literal < a[j].literal }}
+ sort.Sort(s)
+}
diff --git a/src/pkg/compress/flate/inflate.go b/src/pkg/compress/flate/inflate.go
new file mode 100644
index 000000000..3845f1204
--- /dev/null
+++ b/src/pkg/compress/flate/inflate.go
@@ -0,0 +1,708 @@
+// 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 implements the DEFLATE compressed data format, described in
+// RFC 1951. The gzip and zlib packages implement access to DEFLATE-based file
+// formats.
+package flate
+
+import (
+ "bufio"
+ "io"
+ "os"
+ "strconv"
+)
+
+const (
+ maxCodeLen = 16 // max length of Huffman code
+ maxHist = 32768 // max history required
+ maxLit = 286
+ maxDist = 32
+ numCodes = 19 // number of codes in Huffman meta-code
+)
+
+// A CorruptInputError reports the presence of corrupt input at a given offset.
+type CorruptInputError int64
+
+func (e CorruptInputError) String() string {
+ return "flate: corrupt input before offset " + strconv.Itoa64(int64(e))
+}
+
+// An InternalError reports an error in the flate code itself.
+type InternalError string
+
+func (e InternalError) String() string { return "flate: internal error: " + string(e) }
+
+// A ReadError reports an error encountered while reading input.
+type ReadError struct {
+ Offset int64 // byte offset where error occurred
+ Error os.Error // error returned by underlying Read
+}
+
+func (e *ReadError) String() string {
+ return "flate: read error at offset " + strconv.Itoa64(e.Offset) + ": " + e.Error.String()
+}
+
+// A WriteError reports an error encountered while writing output.
+type WriteError struct {
+ Offset int64 // byte offset where error occurred
+ Error os.Error // error returned by underlying Write
+}
+
+func (e *WriteError) String() string {
+ return "flate: write error at offset " + strconv.Itoa64(e.Offset) + ": " + e.Error.String()
+}
+
+// Huffman decoder is based on
+// J. Brian Connell, ``A Huffman-Shannon-Fano Code,''
+// Proceedings of the IEEE, 61(7) (July 1973), pp 1046-1047.
+type huffmanDecoder struct {
+ // min, max code length
+ min, max int
+
+ // limit[i] = largest code word of length i
+ // Given code v of length n,
+ // need more bits if v > limit[n].
+ limit [maxCodeLen + 1]int
+
+ // base[i] = smallest code word of length i - seq number
+ base [maxCodeLen + 1]int
+
+ // codes[seq number] = output code.
+ // Given code v of length n, value is
+ // codes[v - base[n]].
+ codes []int
+}
+
+// Initialize Huffman decoding tables from array of code lengths.
+func (h *huffmanDecoder) init(bits []int) bool {
+ // Count number of codes of each length,
+ // compute min and max length.
+ var count [maxCodeLen + 1]int
+ var min, max int
+ for _, n := range bits {
+ if n == 0 {
+ continue
+ }
+ if min == 0 || n < min {
+ min = n
+ }
+ if n > max {
+ max = n
+ }
+ count[n]++
+ }
+ if max == 0 {
+ return false
+ }
+
+ h.min = min
+ h.max = max
+
+ // For each code range, compute
+ // nextcode (first code of that length),
+ // limit (last code of that length), and
+ // base (offset from first code to sequence number).
+ code := 0
+ seq := 0
+ var nextcode [maxCodeLen]int
+ for i := min; i <= max; i++ {
+ n := count[i]
+ nextcode[i] = code
+ h.base[i] = code - seq
+ code += n
+ seq += n
+ h.limit[i] = code - 1
+ code <<= 1
+ }
+
+ // Make array mapping sequence numbers to codes.
+ if len(h.codes) < len(bits) {
+ h.codes = make([]int, len(bits))
+ }
+ for i, n := range bits {
+ if n == 0 {
+ continue
+ }
+ code := nextcode[n]
+ nextcode[n]++
+ seq := code - h.base[n]
+ h.codes[seq] = i
+ }
+ return true
+}
+
+// Hard-coded Huffman tables for DEFLATE algorithm.
+// See RFC 1951, section 3.2.6.
+var fixedHuffmanDecoder = huffmanDecoder{
+ 7, 9,
+ [maxCodeLen + 1]int{7: 23, 199, 511},
+ [maxCodeLen + 1]int{7: 0, 24, 224},
+ []int{
+ // length 7: 256-279
+ 256, 257, 258, 259, 260, 261, 262,
+ 263, 264, 265, 266, 267, 268, 269,
+ 270, 271, 272, 273, 274, 275, 276,
+ 277, 278, 279,
+
+ // length 8: 0-143
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
+ 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,
+ 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+ 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
+ 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
+ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
+ 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
+ 72, 73, 74, 75, 76, 77, 78, 79, 80, 81,
+ 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,
+ 92, 93, 94, 95, 96, 97, 98, 99, 100,
+ 101, 102, 103, 104, 105, 106, 107, 108,
+ 109, 110, 111, 112, 113, 114, 115, 116,
+ 117, 118, 119, 120, 121, 122, 123, 124,
+ 125, 126, 127, 128, 129, 130, 131, 132,
+ 133, 134, 135, 136, 137, 138, 139, 140,
+ 141, 142, 143,
+
+ // length 8: 280-287
+ 280, 281, 282, 283, 284, 285, 286, 287,
+
+ // length 9: 144-255
+ 144, 145, 146, 147, 148, 149, 150, 151,
+ 152, 153, 154, 155, 156, 157, 158, 159,
+ 160, 161, 162, 163, 164, 165, 166, 167,
+ 168, 169, 170, 171, 172, 173, 174, 175,
+ 176, 177, 178, 179, 180, 181, 182, 183,
+ 184, 185, 186, 187, 188, 189, 190, 191,
+ 192, 193, 194, 195, 196, 197, 198, 199,
+ 200, 201, 202, 203, 204, 205, 206, 207,
+ 208, 209, 210, 211, 212, 213, 214, 215,
+ 216, 217, 218, 219, 220, 221, 222, 223,
+ 224, 225, 226, 227, 228, 229, 230, 231,
+ 232, 233, 234, 235, 236, 237, 238, 239,
+ 240, 241, 242, 243, 244, 245, 246, 247,
+ 248, 249, 250, 251, 252, 253, 254, 255,
+ },
+}
+
+// The actual read interface needed by NewReader.
+// If the passed in io.Reader does not also have ReadByte,
+// the NewReader will introduce its own buffering.
+type Reader interface {
+ io.Reader
+ ReadByte() (c byte, err os.Error)
+}
+
+// Decompress state.
+type decompressor struct {
+ // Input source.
+ r Reader
+ roffset int64
+ woffset int64
+
+ // Input bits, in top of b.
+ b uint32
+ nb uint
+
+ // Huffman decoders for literal/length, distance.
+ h1, h2 huffmanDecoder
+
+ // Length arrays used to define Huffman codes.
+ bits [maxLit + maxDist]int
+ codebits [numCodes]int
+
+ // Output history, buffer.
+ hist [maxHist]byte
+ hp int // current output position in buffer
+ hw int // have written hist[0:hw] already
+ hfull bool // buffer has filled at least once
+
+ // Temporary buffer (avoids repeated allocation).
+ buf [4]byte
+
+ // Next step in the decompression,
+ // and decompression state.
+ step func(*decompressor)
+ final bool
+ err os.Error
+ toRead []byte
+ hl, hd *huffmanDecoder
+ copyLen int
+ copyDist int
+}
+
+func (f *decompressor) nextBlock() {
+ if f.final {
+ if f.hw != f.hp {
+ f.flush((*decompressor).nextBlock)
+ return
+ }
+ f.err = os.EOF
+ return
+ }
+ for f.nb < 1+2 {
+ if f.err = f.moreBits(); f.err != nil {
+ return
+ }
+ }
+ f.final = f.b&1 == 1
+ f.b >>= 1
+ typ := f.b & 3
+ f.b >>= 2
+ f.nb -= 1 + 2
+ switch typ {
+ case 0:
+ f.dataBlock()
+ case 1:
+ // compressed, fixed Huffman tables
+ f.hl = &fixedHuffmanDecoder
+ f.hd = nil
+ f.huffmanBlock()
+ case 2:
+ // compressed, dynamic Huffman tables
+ if f.err = f.readHuffman(); f.err != nil {
+ break
+ }
+ f.hl = &f.h1
+ f.hd = &f.h2
+ f.huffmanBlock()
+ default:
+ // 3 is reserved.
+ f.err = CorruptInputError(f.roffset)
+ }
+}
+
+func (f *decompressor) Read(b []byte) (int, os.Error) {
+ for {
+ if len(f.toRead) > 0 {
+ n := copy(b, f.toRead)
+ f.toRead = f.toRead[n:]
+ return n, nil
+ }
+ if f.err != nil {
+ return 0, f.err
+ }
+ f.step(f)
+ }
+ panic("unreachable")
+}
+
+func (f *decompressor) Close() os.Error {
+ if f.err == os.EOF {
+ return nil
+ }
+ return f.err
+}
+
+// RFC 1951 section 3.2.7.
+// Compression with dynamic Huffman codes
+
+var codeOrder = [...]int{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}
+
+func (f *decompressor) readHuffman() os.Error {
+ // HLIT[5], HDIST[5], HCLEN[4].
+ for f.nb < 5+5+4 {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ nlit := int(f.b&0x1F) + 257
+ f.b >>= 5
+ ndist := int(f.b&0x1F) + 1
+ f.b >>= 5
+ nclen := int(f.b&0xF) + 4
+ f.b >>= 4
+ f.nb -= 5 + 5 + 4
+
+ // (HCLEN+4)*3 bits: code lengths in the magic codeOrder order.
+ for i := 0; i < nclen; i++ {
+ for f.nb < 3 {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ f.codebits[codeOrder[i]] = int(f.b & 0x7)
+ f.b >>= 3
+ f.nb -= 3
+ }
+ for i := nclen; i < len(codeOrder); i++ {
+ f.codebits[codeOrder[i]] = 0
+ }
+ if !f.h1.init(f.codebits[0:]) {
+ return CorruptInputError(f.roffset)
+ }
+
+ // HLIT + 257 code lengths, HDIST + 1 code lengths,
+ // using the code length Huffman code.
+ for i, n := 0, nlit+ndist; i < n; {
+ x, err := f.huffSym(&f.h1)
+ if err != nil {
+ return err
+ }
+ if x < 16 {
+ // Actual length.
+ f.bits[i] = x
+ i++
+ continue
+ }
+ // Repeat previous length or zero.
+ var rep int
+ var nb uint
+ var b int
+ switch x {
+ default:
+ return InternalError("unexpected length code")
+ case 16:
+ rep = 3
+ nb = 2
+ if i == 0 {
+ return CorruptInputError(f.roffset)
+ }
+ b = f.bits[i-1]
+ case 17:
+ rep = 3
+ nb = 3
+ b = 0
+ case 18:
+ rep = 11
+ nb = 7
+ b = 0
+ }
+ for f.nb < nb {
+ if err := f.moreBits(); err != nil {
+ return err
+ }
+ }
+ rep += int(f.b & uint32(1<<nb-1))
+ f.b >>= nb
+ f.nb -= nb
+ if i+rep > n {
+ return CorruptInputError(f.roffset)
+ }
+ for j := 0; j < rep; j++ {
+ f.bits[i] = b
+ i++
+ }
+ }
+
+ if !f.h1.init(f.bits[0:nlit]) || !f.h2.init(f.bits[nlit:nlit+ndist]) {
+ return CorruptInputError(f.roffset)
+ }
+
+ return nil
+}
+
+// Decode a single Huffman block from f.
+// hl and hd are the Huffman states for the lit/length values
+// and the distance values, respectively. If hd == nil, using the
+// fixed distance encoding associated with fixed Huffman blocks.
+func (f *decompressor) huffmanBlock() {
+ for {
+ v, err := f.huffSym(f.hl)
+ if err != nil {
+ f.err = err
+ return
+ }
+ var n uint // number of bits extra
+ var length int
+ switch {
+ case v < 256:
+ f.hist[f.hp] = byte(v)
+ f.hp++
+ if f.hp == len(f.hist) {
+ // After the flush, continue this loop.
+ f.flush((*decompressor).huffmanBlock)
+ return
+ }
+ continue
+ case v == 256:
+ // Done with huffman block; read next block.
+ f.step = (*decompressor).nextBlock
+ return
+ // otherwise, reference to older data
+ case v < 265:
+ length = v - (257 - 3)
+ n = 0
+ case v < 269:
+ length = v*2 - (265*2 - 11)
+ n = 1
+ case v < 273:
+ length = v*4 - (269*4 - 19)
+ n = 2
+ case v < 277:
+ length = v*8 - (273*8 - 35)
+ n = 3
+ case v < 281:
+ length = v*16 - (277*16 - 67)
+ n = 4
+ case v < 285:
+ length = v*32 - (281*32 - 131)
+ n = 5
+ default:
+ length = 258
+ n = 0
+ }
+ if n > 0 {
+ for f.nb < n {
+ if err = f.moreBits(); err != nil {
+ f.err = err
+ return
+ }
+ }
+ length += int(f.b & uint32(1<<n-1))
+ f.b >>= n
+ f.nb -= n
+ }
+
+ var dist int
+ if f.hd == nil {
+ for f.nb < 5 {
+ if err = f.moreBits(); err != nil {
+ f.err = err
+ return
+ }
+ }
+ dist = int(reverseByte[(f.b&0x1F)<<3])
+ f.b >>= 5
+ f.nb -= 5
+ } else {
+ if dist, err = f.huffSym(f.hd); err != nil {
+ f.err = err
+ return
+ }
+ }
+
+ switch {
+ case dist < 4:
+ dist++
+ case dist >= 30:
+ f.err = CorruptInputError(f.roffset)
+ return
+ default:
+ nb := uint(dist-2) >> 1
+ // have 1 bit in bottom of dist, need nb more.
+ extra := (dist & 1) << nb
+ for f.nb < nb {
+ if err = f.moreBits(); err != nil {
+ f.err = err
+ return
+ }
+ }
+ extra |= int(f.b & uint32(1<<nb-1))
+ f.b >>= nb
+ f.nb -= nb
+ dist = 1<<(nb+1) + 1 + extra
+ }
+
+ // Copy history[-dist:-dist+length] into output.
+ if dist > len(f.hist) {
+ f.err = InternalError("bad history distance")
+ return
+ }
+
+ // No check on length; encoding can be prescient.
+ if !f.hfull && dist > f.hp {
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+
+ p := f.hp - dist
+ if p < 0 {
+ p += len(f.hist)
+ }
+ for i := 0; i < length; i++ {
+ f.hist[f.hp] = f.hist[p]
+ f.hp++
+ p++
+ if f.hp == len(f.hist) {
+ // After flush continue copying out of history.
+ f.copyLen = length - (i + 1)
+ f.copyDist = dist
+ f.flush((*decompressor).copyHuff)
+ return
+ }
+ if p == len(f.hist) {
+ p = 0
+ }
+ }
+ }
+ panic("unreached")
+}
+
+func (f *decompressor) copyHuff() {
+ length := f.copyLen
+ dist := f.copyDist
+ p := f.hp - dist
+ if p < 0 {
+ p += len(f.hist)
+ }
+ for i := 0; i < length; i++ {
+ f.hist[f.hp] = f.hist[p]
+ f.hp++
+ p++
+ if f.hp == len(f.hist) {
+ f.copyLen = length - (i + 1)
+ f.flush((*decompressor).copyHuff)
+ return
+ }
+ if p == len(f.hist) {
+ p = 0
+ }
+ }
+
+ // Continue processing Huffman block.
+ f.huffmanBlock()
+}
+
+// Copy a single uncompressed data block from input to output.
+func (f *decompressor) dataBlock() {
+ // Uncompressed.
+ // Discard current half-byte.
+ f.nb = 0
+ f.b = 0
+
+ // Length then ones-complement of length.
+ nr, err := io.ReadFull(f.r, f.buf[0:4])
+ f.roffset += int64(nr)
+ if err != nil {
+ f.err = &ReadError{f.roffset, err}
+ return
+ }
+ n := int(f.buf[0]) | int(f.buf[1])<<8
+ nn := int(f.buf[2]) | int(f.buf[3])<<8
+ if uint16(nn) != uint16(^n) {
+ f.err = CorruptInputError(f.roffset)
+ return
+ }
+
+ if n == 0 {
+ // 0-length block means sync
+ f.flush((*decompressor).nextBlock)
+ return
+ }
+
+ f.copyLen = n
+ f.copyData()
+}
+
+func (f *decompressor) copyData() {
+ // Read f.dataLen bytes into history,
+ // pausing for reads as history fills.
+ n := f.copyLen
+ for n > 0 {
+ m := len(f.hist) - f.hp
+ if m > n {
+ m = n
+ }
+ m, err := io.ReadFull(f.r, f.hist[f.hp:f.hp+m])
+ f.roffset += int64(m)
+ if err != nil {
+ f.err = &ReadError{f.roffset, err}
+ return
+ }
+ n -= m
+ f.hp += m
+ if f.hp == len(f.hist) {
+ f.copyLen = n
+ f.flush((*decompressor).copyData)
+ return
+ }
+ }
+ f.step = (*decompressor).nextBlock
+}
+
+func (f *decompressor) setDict(dict []byte) {
+ if len(dict) > len(f.hist) {
+ // Will only remember the tail.
+ dict = dict[len(dict)-len(f.hist):]
+ }
+
+ f.hp = copy(f.hist[:], dict)
+ if f.hp == len(f.hist) {
+ f.hp = 0
+ f.hfull = true
+ }
+ f.hw = f.hp
+}
+
+func (f *decompressor) moreBits() os.Error {
+ c, err := f.r.ReadByte()
+ if err != nil {
+ if err == os.EOF {
+ err = io.ErrUnexpectedEOF
+ }
+ return err
+ }
+ f.roffset++
+ f.b |= uint32(c) << f.nb
+ f.nb += 8
+ return nil
+}
+
+// Read the next Huffman-encoded symbol from f according to h.
+func (f *decompressor) huffSym(h *huffmanDecoder) (int, os.Error) {
+ for n := uint(h.min); n <= uint(h.max); n++ {
+ lim := h.limit[n]
+ if lim == -1 {
+ continue
+ }
+ for f.nb < n {
+ if err := f.moreBits(); err != nil {
+ return 0, err
+ }
+ }
+ v := int(f.b & uint32(1<<n-1))
+ v <<= 16 - n
+ v = int(reverseByte[v>>8]) | int(reverseByte[v&0xFF])<<8 // reverse bits
+ if v <= lim {
+ f.b >>= n
+ f.nb -= n
+ return h.codes[v-h.base[n]], nil
+ }
+ }
+ return 0, CorruptInputError(f.roffset)
+}
+
+// Flush any buffered output to the underlying writer.
+func (f *decompressor) flush(step func(*decompressor)) {
+ f.toRead = f.hist[f.hw:f.hp]
+ f.woffset += int64(f.hp - f.hw)
+ f.hw = f.hp
+ if f.hp == len(f.hist) {
+ f.hp = 0
+ f.hw = 0
+ f.hfull = true
+ }
+ f.step = step
+}
+
+func makeReader(r io.Reader) Reader {
+ if rr, ok := r.(Reader); ok {
+ return rr
+ }
+ return bufio.NewReader(r)
+}
+
+// NewReader returns a new ReadCloser that can be used
+// to read the uncompressed version of r. It is the caller's
+// responsibility to call Close on the ReadCloser when
+// finished reading.
+func NewReader(r io.Reader) io.ReadCloser {
+ var f decompressor
+ f.r = makeReader(r)
+ f.step = (*decompressor).nextBlock
+ return &f
+}
+
+// NewReaderDict is like NewReader but initializes the reader
+// with a preset dictionary. The returned Reader behaves as if
+// the uncompressed data stream started with the given dictionary,
+// which has already been read. NewReaderDict is typically used
+// to read data compressed by NewWriterDict.
+func NewReaderDict(r io.Reader, dict []byte) io.ReadCloser {
+ var f decompressor
+ f.setDict(dict)
+ f.r = makeReader(r)
+ f.step = (*decompressor).nextBlock
+ return &f
+}
diff --git a/src/pkg/compress/flate/reverse_bits.go b/src/pkg/compress/flate/reverse_bits.go
new file mode 100644
index 000000000..c1a02720d
--- /dev/null
+++ b/src/pkg/compress/flate/reverse_bits.go
@@ -0,0 +1,48 @@
+// 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
+
+var reverseByte = [256]byte{
+ 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
+ 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
+ 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
+ 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
+ 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
+ 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
+ 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
+ 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
+ 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
+ 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
+ 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
+ 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
+ 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
+ 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
+ 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
+ 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
+ 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
+ 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
+ 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
+ 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
+ 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
+ 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
+ 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
+ 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
+ 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
+ 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
+ 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
+ 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
+ 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
+ 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
+ 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
+ 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
+}
+
+func reverseUint16(v uint16) uint16 {
+ return uint16(reverseByte[v>>8]) | uint16(reverseByte[v&0xFF])<<8
+}
+
+func reverseBits(number uint16, bitLength byte) uint16 {
+ return reverseUint16(number << uint8(16-bitLength))
+}
diff --git a/src/pkg/compress/flate/token.go b/src/pkg/compress/flate/token.go
new file mode 100644
index 000000000..38aea5fa6
--- /dev/null
+++ b/src/pkg/compress/flate/token.go
@@ -0,0 +1,103 @@
+// 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
+
+const (
+ // 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
+)
+
+// The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH)
+// is lengthCodes[length - MIN_MATCH_LENGTH]
+var lengthCodes = [...]uint32{
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
+ 9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
+ 13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
+ 15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
+ 17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
+ 18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
+ 19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
+ 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
+ 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
+ 21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
+ 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
+ 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
+ 23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
+ 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+ 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+ 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
+ 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+ 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+ 25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
+ 25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
+ 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+ 26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
+ 26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
+ 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+ 27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
+ 27, 27, 27, 27, 27, 28,
+}
+
+var offsetCodes = [...]uint32{
+ 0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
+ 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
+ 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
+ 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
+ 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+ 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
+ 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+ 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+ 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
+}
+
+type token uint32
+
+// Convert a literal into a literal token.
+func literalToken(literal uint32) token { return token(literalType + literal) }
+
+// Convert a < xlength, xoffset > pair into a match token.
+func matchToken(xlength uint32, xoffset uint32) token {
+ return token(matchType + xlength<<lengthShift + xoffset)
+}
+
+// Returns the type of a token
+func (t token) typ() uint32 { return uint32(t) & typeMask }
+
+// Returns the literal of a literal token
+func (t token) literal() uint32 { return uint32(t - literalType) }
+
+// Returns the extra offset of a match token
+func (t token) offset() uint32 { return uint32(t) & offsetMask }
+
+func (t token) length() uint32 { return uint32((t - matchType) >> lengthShift) }
+
+func lengthCode(len uint32) uint32 { return lengthCodes[len] }
+
+// Returns the offset code corresponding to a specific offset
+func offsetCode(off uint32) uint32 {
+ const n = uint32(len(offsetCodes))
+ switch {
+ case off < n:
+ return offsetCodes[off]
+ case off>>7 < n:
+ return offsetCodes[off>>7] + 14
+ default:
+ return offsetCodes[off>>14] + 28
+ }
+ panic("unreachable")
+}
diff --git a/src/pkg/compress/flate/util.go b/src/pkg/compress/flate/util.go
new file mode 100644
index 000000000..aca5c78b2
--- /dev/null
+++ b/src/pkg/compress/flate/util.go
@@ -0,0 +1,72 @@
+// 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
+
+func min(left int, right int) int {
+ if left < right {
+ return left
+ }
+ return right
+}
+
+func minInt32(left int32, right int32) int32 {
+ if left < right {
+ return left
+ }
+ return right
+}
+
+func max(left int, right int) int {
+ if left > right {
+ return left
+ }
+ return right
+}
+
+func fillInts(a []int, value int) {
+ for i := range a {
+ a[i] = value
+ }
+}
+
+func fillInt32s(a []int32, value int32) {
+ for i := range a {
+ a[i] = value
+ }
+}
+
+func fillBytes(a []byte, value byte) {
+ for i := range a {
+ a[i] = value
+ }
+}
+
+func fillInt8s(a []int8, value int8) {
+ for i := range a {
+ a[i] = value
+ }
+}
+
+func fillUint8s(a []uint8, value uint8) {
+ for i := range a {
+ a[i] = value
+ }
+}
+
+func copyInt8s(dst []int8, src []int8) int {
+ cnt := min(len(dst), len(src))
+ for i := 0; i < cnt; i++ {
+ dst[i] = src[i]
+ }
+ return cnt
+}
+
+func copyUint8s(dst []uint8, src []uint8) int {
+ cnt := min(len(dst), len(src))
+ for i := 0; i < cnt; i++ {
+ dst[i] = src[i]
+ }
+ return cnt
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-21 20:21:54 +0000