Add test/data/artificial GIF data
diff --git a/script/make-artificial.go b/script/make-artificial.go
new file mode 100644
index 0000000..623de2e
--- /dev/null
+++ b/script/make-artificial.go
@@ -0,0 +1,665 @@
+// Copyright 2018 The Wuffs Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build ignore
+
+package main
+
+// make-artificial.go makes test data in various formats.
+//
+// See test/data/artificial/*.make.txt for examples.
+//
+// Usage: go run make-artificial.go < foo.make.txt
+
+import (
+ "bytes"
+ "compress/lzw"
+ "fmt"
+ "io/ioutil"
+ "os"
+ "strconv"
+ "strings"
+)
+
+type stateFunc func(line string) (stateFunc, error)
+
+type repeat struct {
+ count uint32
+ remaining string
+}
+
+var (
+ state stateFunc
+ repeats []repeat
+ out []byte
+ formats = map[string]stateFunc{}
+)
+
+func main() {
+ if err := main1(); err != nil {
+ os.Stderr.WriteString(err.Error() + "\n")
+ os.Exit(1)
+ }
+}
+
+func main1() error {
+ stdin, err := ioutil.ReadAll(os.Stdin)
+ if err != nil {
+ return err
+ }
+ s := string(stdin)
+ for remaining := ""; len(s) > 0; s, remaining = remaining, "" {
+ if i := strings.IndexByte(s, '\n'); i >= 0 {
+ s, remaining = s[:i], s[i+1:]
+ }
+ s = strings.TrimSpace(s)
+ if s == "" || s[0] == '#' {
+ continue
+ }
+
+ if state == nil {
+ const m = "make "
+ if !strings.HasPrefix(s, m) {
+ return fmt.Errorf(`input must start with "make foo"`)
+ }
+ s = s[len(m):]
+ state = formats[s]
+ if state == nil {
+ return fmt.Errorf("unsupported format %q", s)
+ }
+ continue
+ }
+
+ const rep = "repeat "
+ if strings.HasPrefix(s, rep) {
+ args := s[len(rep):]
+ count, args, ok := parseNum(args)
+ if !ok || count <= 0 || args != "[" {
+ return fmt.Errorf("bad repeat command: %q", s)
+ }
+ repeats = append(repeats, repeat{
+ count: count,
+ remaining: remaining,
+ })
+ continue
+ }
+
+ if s == "]" {
+ if len(repeats) <= 0 {
+ return fmt.Errorf(`unbalanced close-repeat command: "]"`)
+ }
+ i := len(repeats) - 1
+ repeats[i].count--
+ if repeats[i].count == 0 {
+ repeats = repeats[:i]
+ } else {
+ remaining = repeats[i].remaining
+ }
+ continue
+ }
+
+ state, err = state(s)
+ if err != nil {
+ return err
+ }
+ if state == nil {
+ return fmt.Errorf("bad state transition")
+ }
+ }
+
+ _, err = os.Stdout.Write(out)
+ return err
+}
+
+// ----
+
+func appendU16LE(b []byte, u uint16) []byte {
+ return append(b, uint8(u), uint8(u>>8))
+}
+
+func log2(u uint32) (i int32) {
+ for i, pow := uint32(0), uint32(1); i < 32; i, pow = i+1, pow<<1 {
+ if u == pow {
+ return int32(i)
+ }
+ if u < pow {
+ break
+ }
+ }
+ return -1
+}
+
+func parseHex(s string) (num uint32, remaining string, ok bool) {
+ if i := strings.IndexByte(s, ' '); i >= 0 {
+ s, remaining = s[:i], s[i+1:]
+ for len(remaining) > 0 && remaining[0] == ' ' {
+ remaining = remaining[1:]
+ }
+ }
+
+ if len(s) < 2 || s[0] != '0' || s[1] != 'x' {
+ return 0, "", false
+ }
+ s = s[2:]
+
+ u, err := strconv.ParseUint(s, 16, 32)
+ if err != nil {
+ return 0, "", false
+ }
+ return uint32(u), remaining, true
+}
+
+func parseNum(s string) (num uint32, remaining string, ok bool) {
+ if i := strings.IndexByte(s, ' '); i >= 0 {
+ s, remaining = s[:i], s[i+1:]
+ for len(remaining) > 0 && remaining[0] == ' ' {
+ remaining = remaining[1:]
+ }
+ }
+
+ u, err := strconv.ParseUint(s, 10, 32)
+ if err != nil {
+ return 0, "", false
+ }
+ return uint32(u), remaining, true
+}
+
+func reverse(x uint32, n uint32) uint32 {
+ x = uint32(reverse8[0xFF&(x>>0)])<<24 |
+ uint32(reverse8[0xFF&(x>>8)])<<16 |
+ uint32(reverse8[0xFF&(x>>16)])<<8 |
+ uint32(reverse8[0xFF&(x>>24)])<<0
+ return x >> (32 - n)
+}
+
+var reverse8 = [256]byte{
+ 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, // 0x00 - 0x07
+ 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, // 0x08 - 0x0F
+ 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, // 0x10 - 0x17
+ 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, // 0x18 - 0x1F
+ 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, // 0x20 - 0x27
+ 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, // 0x28 - 0x2F
+ 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, // 0x30 - 0x37
+ 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, // 0x38 - 0x3F
+ 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, // 0x40 - 0x47
+ 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, // 0x48 - 0x4F
+ 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, // 0x50 - 0x57
+ 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, // 0x58 - 0x5F
+ 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, // 0x60 - 0x67
+ 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, // 0x68 - 0x6F
+ 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, // 0x70 - 0x77
+ 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, // 0x78 - 0x7F
+ 0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, // 0x80 - 0x87
+ 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1, // 0x88 - 0x8F
+ 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, // 0x90 - 0x97
+ 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, // 0x98 - 0x9F
+ 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, // 0xA0 - 0xA7
+ 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, // 0xA8 - 0xAF
+ 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, // 0xB0 - 0xB7
+ 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, // 0xB8 - 0xBF
+ 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, // 0xC0 - 0xC7
+ 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, // 0xC8 - 0xCF
+ 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, // 0xD0 - 0xD7
+ 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, // 0xD8 - 0xDF
+ 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, // 0xE0 - 0xE7
+ 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, // 0xE8 - 0xEF
+ 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, // 0xF0 - 0xF7
+ 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF, // 0xF8 - 0xFF
+}
+
+// ----
+
+func init() {
+ formats["deflate"] = stateDeflate
+}
+
+var deflateGlobals struct {
+ bncData []byte
+ stream deflateBitStream
+}
+
+func stateDeflate(line string) (stateFunc, error) {
+ g := &deflateGlobals
+ const (
+ cmdBNC = "blockNoCompression "
+ cmdBFH = "blockFixedHuffman "
+ )
+ bits := uint32(0)
+ s := ""
+
+ retState := stateFunc(nil)
+ switch {
+ case strings.HasPrefix(line, cmdBNC):
+ s = line[len(cmdBNC):]
+ retState = stateDeflateNoCompression
+ bits |= 0 << 1
+ case strings.HasPrefix(line, cmdBFH):
+ s = line[len(cmdBFH):]
+ retState = stateDeflateFixedHuffman
+ bits |= 1 << 1
+ default:
+ return nil, fmt.Errorf("bad stateDeflate command: %q", line)
+ }
+
+ switch s {
+ case "(final) {":
+ bits |= 1
+ case "(nonFinal) {":
+ // No-op.
+ default:
+ return nil, fmt.Errorf("bad stateDeflate command: %q", line)
+ }
+
+ g.stream.writeBits(bits, 3)
+ return retState, nil
+}
+
+func stateDeflateNoCompression(line string) (stateFunc, error) {
+ g := &deflateGlobals
+ if line == "}" {
+ if len(g.bncData) > 0xFFFF {
+ return nil, fmt.Errorf("bncData is too long")
+ }
+ n := uint32(len(g.bncData))
+ g.stream.flush()
+ g.stream.writeBits(n, 16)
+ g.stream.writeBits(0xFFFF-n, 16)
+ g.stream.writeBytes(g.bncData)
+ g.bncData = g.bncData[:0]
+ return stateDeflate, nil
+ }
+
+ if lit, ok := deflateParseLiteral(line); ok {
+ g.bncData = append(g.bncData, lit...)
+ return stateDeflateNoCompression, nil
+ }
+
+ return nil, fmt.Errorf("bad blockNoCompression command: %q", line)
+}
+
+func stateDeflateFixedHuffman(line string) (stateFunc, error) {
+ g := &deflateGlobals
+ if line == "}" {
+ g.stream.flush()
+ return stateDeflate, nil
+ }
+
+ if line == "endOfBlock" {
+ g.stream.writeBits(0, 7)
+ return stateDeflateFixedHuffman, nil
+ }
+
+ if lit, ok := deflateParseLiteral(line); ok {
+ // TODO: support "\xAB" escape codes in the script?
+ for i := 0; i < len(lit); i++ {
+ g.stream.writeLCode(uint32(lit[i]))
+ }
+ return stateDeflateFixedHuffman, nil
+ }
+
+ if l, d, ok := deflateParseLenDist(line); ok {
+ lCode, lExtra, lNExtra := deflateEncodeLength(l)
+ g.stream.writeLCode(lCode)
+ g.stream.writeBits(lExtra, lNExtra)
+ dCode, dExtra, dNExtra := deflateEncodeDistance(d)
+ g.stream.writeBits(reverse(dCode, 5), 5)
+ g.stream.writeBits(dExtra, dNExtra)
+ return stateDeflateFixedHuffman, nil
+ }
+
+ return nil, fmt.Errorf("bad stateDeflateFixedHuffman command: %q", line)
+}
+
+type deflateBitStream struct {
+ bits uint32
+ nBits uint32 // Always within [0, 7].
+}
+
+// writeBits writes the low n bits of b to z.
+func (z *deflateBitStream) writeBits(b uint32, n uint32) {
+ if n > 24 {
+ panic("writeBits: n is too large")
+ }
+ z.bits |= b << z.nBits
+ z.nBits += n
+ for z.nBits >= 8 {
+ out = append(out, uint8(z.bits))
+ z.bits >>= 8
+ z.nBits -= 8
+ }
+}
+
+func (z *deflateBitStream) writeBytes(b []byte) {
+ z.flush()
+ out = append(out, b...)
+}
+
+func (z *deflateBitStream) writeLCode(lCode uint32) {
+ switch {
+ case lCode < 144: // 0b._0011_0000 through 0b._1011_1111
+ lCode += 0x030
+ z.writeBits(reverse(lCode, 8), 8)
+ case lCode < 256: // 0b1_1001_0000 through 0b1_1111_1111
+ lCode += 0x190 - 144
+ z.writeBits(reverse(lCode, 9), 9)
+ case lCode < 280: // 0b._.000_0000 through 0b._.001_0111
+ lCode -= 256 - 0x000
+ z.writeBits(reverse(lCode, 7), 7)
+ default: // 0b._1100_0000 through 0b._1100_0111
+ lCode -= 280 - 0x0C0
+ z.writeBits(reverse(lCode, 8), 8)
+ }
+}
+
+func (z *deflateBitStream) flush() {
+ if z.nBits > 0 {
+ out = append(out, uint8(z.bits))
+ z.bits = 0
+ z.nBits = 0
+ }
+}
+
+func deflateEncodeLength(l uint32) (code uint32, extra uint32, nExtra uint32) {
+ switch {
+ case l < 3:
+ // No-op.
+ case l < 11:
+ l -= 3
+ return (l >> 0) + 257, l & 0x0000, 0
+ case l < 19:
+ l -= 11
+ return (l >> 1) + 265, l & 0x0001, 1
+ case l < 35:
+ l -= 19
+ return (l >> 2) + 269, l & 0x0003, 2
+ case l < 67:
+ l -= 35
+ return (l >> 3) + 273, l & 0x0007, 3
+ case l < 131:
+ l -= 67
+ return (l >> 4) + 277, l & 0x000F, 4
+ case l < 258:
+ l -= 131
+ return (l >> 5) + 281, l & 0x001F, 5
+ case l == 258:
+ return 285, 0, 0
+ }
+ panic(fmt.Sprintf("deflateEncodeLength: l=%d", l))
+}
+
+func deflateEncodeDistance(d uint32) (code uint32, extra uint32, nExtra uint32) {
+ switch {
+ case d < 1:
+ // No-op.
+ case d < 5:
+ d -= 1
+ return (d >> 0) + 0, d & 0x0000, 0
+ case d < 9:
+ d -= 5
+ return (d >> 1) + 4, d & 0x0001, 1
+ case d < 17:
+ d -= 9
+ return (d >> 2) + 6, d & 0x0003, 2
+ case d < 33:
+ d -= 17
+ return (d >> 3) + 8, d & 0x0007, 3
+ case d < 65:
+ d -= 33
+ return (d >> 4) + 10, d & 0x000F, 4
+ case d < 129:
+ d -= 65
+ return (d >> 5) + 12, d & 0x001F, 5
+ case d < 257:
+ d -= 129
+ return (d >> 6) + 14, d & 0x003F, 6
+ case d < 513:
+ d -= 257
+ return (d >> 7) + 16, d & 0x007F, 7
+ case d < 1025:
+ d -= 513
+ return (d >> 8) + 18, d & 0x00FF, 8
+ case d < 2049:
+ d -= 1025
+ return (d >> 9) + 20, d & 0x01FF, 9
+ case d < 4097:
+ d -= 2049
+ return (d >> 10) + 22, d & 0x03FF, 10
+ case d < 8193:
+ d -= 4097
+ return (d >> 11) + 24, d & 0x07FF, 11
+ case d < 16385:
+ d -= 8193
+ return (d >> 12) + 26, d & 0x0FFF, 12
+ case d < 32769:
+ d -= 16385
+ return (d >> 13) + 28, d & 0x1FFF, 13
+ }
+ panic(fmt.Sprintf("deflateEncodeDistance: d=%d", d))
+}
+
+func deflateParseLiteral(s string) (lit string, ok bool) {
+ const (
+ prefix = `literal "`
+ suffix = `"`
+ )
+ if strings.HasPrefix(s, prefix) {
+ s = s[len(prefix):]
+ if strings.HasSuffix(s, suffix) {
+ return s[:len(s)-len(suffix)], true
+ }
+ }
+ return "", false
+}
+
+func deflateParseLenDist(line string) (l uint32, d uint32, ok bool) {
+ const (
+ lStr = "len "
+ dStr = "dist "
+ )
+ s := line
+ if strings.HasPrefix(s, lStr) {
+ s = s[len(lStr):]
+ if l, s, ok := parseNum(s); ok && 3 <= l && l <= 258 {
+ if strings.HasPrefix(s, dStr) {
+ s = s[len(dStr):]
+ if d, s, ok := parseNum(s); ok && 1 <= d && d <= 32768 && s == "" {
+ return l, d, true
+ }
+ }
+ }
+ }
+ return 0, 0, false
+}
+
+// ----
+
+func init() {
+ formats["gif"] = stateGif
+}
+
+var gifGlobals struct {
+ imageWidth uint32
+ imageHeight uint32
+
+ frameLeft uint32
+ frameTop uint32
+ frameWidth uint32
+ frameHeight uint32
+
+ globalPalette [][4]uint8
+}
+
+func stateGif(line string) (stateFunc, error) {
+ const (
+ cmdL = "lzw "
+ )
+outer:
+ switch {
+ case line == "frame {":
+ out = append(out, 0x2C)
+ return stateGifFrame, nil
+
+ case line == "header":
+ out = append(out, "GIF89a"...)
+ return stateGif, nil
+
+ case line == "image {":
+ return stateGifImage, nil
+
+ case line == "trailer":
+ out = append(out, 0x3B)
+ return stateGif, nil
+
+ case strings.HasPrefix(line, cmdL):
+ s := line[len(cmdL):]
+ litWidth, s, ok := parseNum(s)
+ if !ok || litWidth < 2 || 8 < litWidth {
+ break
+ }
+ out = append(out, uint8(litWidth))
+
+ uncompressed := []byte(nil)
+ for s != "" {
+ x := uint32(0)
+ x, s, ok = parseHex(s)
+ if !ok {
+ break outer
+ }
+ uncompressed = append(uncompressed, uint8(x))
+ }
+
+ buf := bytes.NewBuffer(nil)
+ w := lzw.NewWriter(buf, lzw.LSB, int(litWidth))
+ if _, err := w.Write(uncompressed); err != nil {
+ return nil, err
+ }
+ if err := w.Close(); err != nil {
+ return nil, err
+ }
+ compressed := buf.Bytes()
+
+ for len(compressed) > 0 {
+ if len(compressed) <= 0xFF {
+ out = append(out, uint8(len(compressed)))
+ out = append(out, compressed...)
+ compressed = nil
+ } else {
+ out = append(out, 0xFF)
+ out = append(out, compressed[:0xFF]...)
+ compressed = compressed[0xFF:]
+ }
+ }
+ out = append(out, 0x00)
+ return stateGif, nil
+ }
+
+ return nil, fmt.Errorf("bad stateGif command: %q", line)
+}
+
+func stateGifImage(line string) (stateFunc, error) {
+ g := &gifGlobals
+ if line == "}" {
+ out = appendU16LE(out, uint16(g.imageWidth))
+ out = appendU16LE(out, uint16(g.imageHeight))
+ if g.globalPalette == nil {
+ out = append(out, 0x00)
+ } else if n := log2(uint32(len(g.globalPalette))); n < 2 || 8 < n {
+ return nil, fmt.Errorf("bad len(g.globalPalette): %d", len(g.globalPalette))
+ } else {
+ out = append(out, 0x80|uint8(n-1))
+ }
+ out = append(out, 0x00) // TODO: background index.
+ out = append(out, 0x00)
+ for _, x := range g.globalPalette {
+ out = append(out, x[0], x[1], x[2])
+ }
+ return stateGif, nil
+ }
+
+ const (
+ cmdIWH = "imageWidthHeight "
+ cmdP = "palette {"
+ )
+ switch {
+ case strings.HasPrefix(line, cmdIWH):
+ s := line[len(cmdIWH):]
+ if w, s, ok := parseNum(s); ok {
+ if h, _, ok := parseNum(s); ok {
+ g.imageWidth = w
+ g.imageHeight = h
+ return stateGifImage, nil
+ }
+ }
+
+ case strings.HasPrefix(line, cmdP):
+ return stateGifImagePalette, nil
+ }
+
+ return nil, fmt.Errorf("bad stateGifImage command: %q", line)
+}
+
+func stateGifFrame(line string) (stateFunc, error) {
+ g := &gifGlobals
+ if line == "}" {
+ out = appendU16LE(out, uint16(g.frameLeft))
+ out = appendU16LE(out, uint16(g.frameTop))
+ out = appendU16LE(out, uint16(g.frameWidth))
+ out = appendU16LE(out, uint16(g.frameHeight))
+ out = append(out, 0x00) // TODO: flags.
+ return stateGif, nil
+ }
+
+ const (
+ cmdFLTWH = "frameLeftTopWidthHeight "
+ )
+ switch {
+ case strings.HasPrefix(line, cmdFLTWH):
+ s := line[len(cmdFLTWH):]
+ if l, s, ok := parseNum(s); ok {
+ if t, s, ok := parseNum(s); ok {
+ if w, s, ok := parseNum(s); ok {
+ if h, _, ok := parseNum(s); ok {
+ g.frameLeft = l
+ g.frameTop = t
+ g.frameWidth = w
+ g.frameHeight = h
+ return stateGifFrame, nil
+ }
+ }
+ }
+ }
+ }
+
+ return nil, fmt.Errorf("bad stateGifFrame command: %q", line)
+}
+
+func stateGifImagePalette(line string) (stateFunc, error) {
+ g := &gifGlobals
+ if line == "}" {
+ return stateGifImage, nil
+ }
+
+ s := line
+ if rgb0, s, ok := parseHex(s); ok {
+ if rgb1, s, ok := parseHex(s); ok {
+ if rgb2, _, ok := parseHex(s); ok {
+ g.globalPalette = append(g.globalPalette,
+ [4]uint8{uint8(rgb0), uint8(rgb1), uint8(rgb2), 0xFF})
+ return stateGifImagePalette, nil
+ }
+ }
+ }
+
+ return nil, fmt.Errorf("bad stateGifImagePalette command: %q", line)
+}
diff --git a/script/make-deflate.go b/script/make-deflate.go
deleted file mode 100644
index 9781623..0000000
--- a/script/make-deflate.go
+++ /dev/null
@@ -1,426 +0,0 @@
-// Copyright 2018 The Wuffs Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build ignore
-
-package main
-
-// make-deflate.go makes some data in the deflate format.
-//
-// See test/data/artificial/*.deflate.make.txt for examples.
-//
-// Usage: go run make-deflate.go < foo.make.txt
-
-import (
- "fmt"
- "io/ioutil"
- "os"
- "strconv"
- "strings"
-)
-
-// Global state.
-var (
- block uint32
- bncData []byte
- repeats []repeat
- stream bitStream
-)
-
-const (
- blockZero = 0
- blockNoCompression = 1
- blockFixedHuffman = 2
- // TODO: blockDynamicHuffman.
-)
-
-var doFuncs = [...]func(s string) error{
- blockZero: doBlockZero,
- blockNoCompression: doBlockNoCompression,
- blockFixedHuffman: doBlockFixedHuffman,
-}
-
-type bitStream struct {
- buf []byte
- bits uint32
- nBits uint32 // Always within [0, 7].
-}
-
-// writeBits writes the low n bits of b to z.
-func (z *bitStream) writeBits(b uint32, n uint32) {
- if n > 24 {
- panic("writeBits: n is too large")
- }
- z.bits |= b << z.nBits
- z.nBits += n
- for z.nBits >= 8 {
- z.buf = append(z.buf, uint8(z.bits))
- z.bits >>= 8
- z.nBits -= 8
- }
-}
-
-func (z *bitStream) writeBytes(b []byte) {
- z.flush()
- z.buf = append(z.buf, b...)
-}
-
-func (z *bitStream) writeLCode(lCode uint32) {
- switch {
- case lCode < 144: // 0b._0011_0000 through 0b._1011_1111
- lCode += 0x030
- z.writeBits(reverse(lCode, 8), 8)
- case lCode < 256: // 0b1_1001_0000 through 0b1_1111_1111
- lCode += 0x190 - 144
- z.writeBits(reverse(lCode, 9), 9)
- case lCode < 280: // 0b._.000_0000 through 0b._.001_0111
- lCode -= 256 - 0x000
- z.writeBits(reverse(lCode, 7), 7)
- default: // 0b._1100_0000 through 0b._1100_0111
- lCode -= 280 - 0x0C0
- z.writeBits(reverse(lCode, 8), 8)
- }
-}
-
-func (z *bitStream) flush() {
- if z.nBits > 0 {
- z.buf = append(z.buf, uint8(z.bits))
- z.bits = 0
- z.nBits = 0
- }
-}
-
-type repeat struct {
- count uint32
- remaining string
-}
-
-func main() {
- if err := main1(); err != nil {
- os.Stderr.WriteString(err.Error() + "\n")
- os.Exit(1)
- }
-}
-
-func main1() error {
- stdin, err := ioutil.ReadAll(os.Stdin)
- if err != nil {
- return err
- }
- s := string(stdin)
- for remaining := ""; len(s) > 0; s, remaining = remaining, "" {
- if i := strings.IndexByte(s, '\n'); i >= 0 {
- s, remaining = s[:i], s[i+1:]
- }
- s = strings.TrimSpace(s)
- if s == "" || s[0] == '#' {
- continue
- }
-
- const rep = "repeat "
- if strings.HasPrefix(s, rep) {
- args := s[len(rep):]
- count, args, ok := parseNum(args)
- if !ok || count <= 0 || args != "[" {
- return fmt.Errorf("bad repeat command: %q", s)
- }
- repeats = append(repeats, repeat{
- count: count,
- remaining: remaining,
- })
- continue
- }
-
- if s == "]" {
- if len(repeats) <= 0 {
- return fmt.Errorf(`unbalanced close-repeat command: "]"`)
- }
- i := len(repeats) - 1
- repeats[i].count--
- if repeats[i].count == 0 {
- repeats = repeats[:i]
- } else {
- remaining = repeats[i].remaining
- }
- continue
- }
-
- if err := doFuncs[block](s); err != nil {
- return err
- }
- }
-
- stream.flush()
- _, err = os.Stdout.Write(stream.buf)
- return err
-}
-
-func doBlockZero(line string) error {
- const (
- bnc = "blockNoCompression "
- bfh = "blockFixedHuffman "
- )
- bits := uint32(0)
- s := ""
-
- switch {
- case strings.HasPrefix(line, bnc):
- s = line[len(bnc):]
- block = blockNoCompression
- bits |= 0 << 1
- case strings.HasPrefix(line, bfh):
- s = line[len(bfh):]
- block = blockFixedHuffman
- bits |= 1 << 1
- default:
- return fmt.Errorf("bad blockZero command: %q", line)
- }
-
- switch s {
- case "(final) {":
- bits |= 1
- case "(nonFinal) {":
- // No-op.
- default:
- return fmt.Errorf("bad blockZero command: %q", line)
- }
-
- stream.writeBits(bits, 3)
- return nil
-}
-
-func doBlockNoCompression(line string) error {
- if line == "}" {
- if len(bncData) > 0xFFFF {
- return fmt.Errorf("bncData is too long")
- }
- n := uint32(len(bncData))
- stream.flush()
- stream.writeBits(n, 16)
- stream.writeBits(0xFFFF-n, 16)
- stream.writeBytes(bncData)
- bncData = bncData[:0]
- block = blockZero
- return nil
- }
-
- if lit, ok := parseLiteral(line); ok {
- bncData = append(bncData, lit...)
- return nil
- }
-
- return fmt.Errorf("bad blockNoCompression command: %q", line)
-}
-
-func doBlockFixedHuffman(line string) error {
- if line == "}" {
- block = blockZero
- return nil
- }
-
- if line == "endOfBlock" {
- stream.writeBits(0, 7)
- return nil
- }
-
- if lit, ok := parseLiteral(line); ok {
- // TODO: support "\xAB" escape codes in the script?
- for i := 0; i < len(lit); i++ {
- stream.writeLCode(uint32(lit[i]))
- }
- return nil
- }
-
- if l, d, ok := parseLenDist(line); ok {
- lCode, lExtra, lNExtra := encodeLength(l)
- stream.writeLCode(lCode)
- stream.writeBits(lExtra, lNExtra)
- dCode, dExtra, dNExtra := encodeDistance(d)
- stream.writeBits(reverse(dCode, 5), 5)
- stream.writeBits(dExtra, dNExtra)
- return nil
- }
-
- return fmt.Errorf("bad blockFixedHuffman command: %q", line)
-}
-
-func encodeLength(l uint32) (code uint32, extra uint32, nExtra uint32) {
- switch {
- case l < 3:
- // No-op.
- case l < 11:
- l -= 3
- return (l >> 0) + 257, l & 0x0000, 0
- case l < 19:
- l -= 11
- return (l >> 1) + 265, l & 0x0001, 1
- case l < 35:
- l -= 19
- return (l >> 2) + 269, l & 0x0003, 2
- case l < 67:
- l -= 35
- return (l >> 3) + 273, l & 0x0007, 3
- case l < 131:
- l -= 67
- return (l >> 4) + 277, l & 0x000F, 4
- case l < 258:
- l -= 131
- return (l >> 5) + 281, l & 0x001F, 5
- case l == 258:
- return 285, 0, 0
- }
- panic(fmt.Sprintf("encodeLength: l=%d", l))
-}
-
-func encodeDistance(d uint32) (code uint32, extra uint32, nExtra uint32) {
- switch {
- case d < 1:
- // No-op.
- case d < 5:
- d -= 1
- return (d >> 0) + 0, d & 0x0000, 0
- case d < 9:
- d -= 5
- return (d >> 1) + 4, d & 0x0001, 1
- case d < 17:
- d -= 9
- return (d >> 2) + 6, d & 0x0003, 2
- case d < 33:
- d -= 17
- return (d >> 3) + 8, d & 0x0007, 3
- case d < 65:
- d -= 33
- return (d >> 4) + 10, d & 0x000F, 4
- case d < 129:
- d -= 65
- return (d >> 5) + 12, d & 0x001F, 5
- case d < 257:
- d -= 129
- return (d >> 6) + 14, d & 0x003F, 6
- case d < 513:
- d -= 257
- return (d >> 7) + 16, d & 0x007F, 7
- case d < 1025:
- d -= 513
- return (d >> 8) + 18, d & 0x00FF, 8
- case d < 2049:
- d -= 1025
- return (d >> 9) + 20, d & 0x01FF, 9
- case d < 4097:
- d -= 2049
- return (d >> 10) + 22, d & 0x03FF, 10
- case d < 8193:
- d -= 4097
- return (d >> 11) + 24, d & 0x07FF, 11
- case d < 16385:
- d -= 8193
- return (d >> 12) + 26, d & 0x0FFF, 12
- case d < 32769:
- d -= 16385
- return (d >> 13) + 28, d & 0x1FFF, 13
- }
- panic(fmt.Sprintf("encodeDistance: d=%d", d))
-}
-
-func reverse(x uint32, n uint32) uint32 {
- x = uint32(reverse8[0xFF&(x>>0)])<<24 |
- uint32(reverse8[0xFF&(x>>8)])<<16 |
- uint32(reverse8[0xFF&(x>>16)])<<8 |
- uint32(reverse8[0xFF&(x>>24)])<<0
- return x >> (32 - n)
-}
-
-var reverse8 = [256]byte{
- 0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, // 0x00 - 0x07
- 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0, // 0x08 - 0x0F
- 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, // 0x10 - 0x17
- 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, // 0x18 - 0x1F
- 0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, // 0x20 - 0x27
- 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4, // 0x28 - 0x2F
- 0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, // 0x30 - 0x37
- 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC, // 0x38 - 0x3F
- 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, // 0x40 - 0x47
- 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, // 0x48 - 0x4F
- 0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, // 0x50 - 0x57
- 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA, // 0x58 - 0x5F
- 0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, // 0x60 - 0x67
- 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6, // 0x68 - 0x6F
- 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, // 0x70 - 0x77
- 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, // 0x78 - 0x7F
- 0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, // 0x80 - 0x87
- 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1, // 0x88 - 0x8F
- 0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, // 0x90 - 0x97
- 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9, // 0x98 - 0x9F
- 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, // 0xA0 - 0xA7
- 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, // 0xA8 - 0xAF
- 0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, // 0xB0 - 0xB7
- 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD, // 0xB8 - 0xBF
- 0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, // 0xC0 - 0xC7
- 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3, // 0xC8 - 0xCF
- 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, // 0xD0 - 0xD7
- 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, // 0xD8 - 0xDF
- 0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, // 0xE0 - 0xE7
- 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7, // 0xE8 - 0xEF
- 0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, // 0xF0 - 0xF7
- 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF, // 0xF8 - 0xFF
-}
-
-func parseLiteral(s string) (lit string, ok bool) {
- const (
- prefix = `literal "`
- suffix = `"`
- )
- if strings.HasPrefix(s, prefix) {
- s = s[len(prefix):]
- if strings.HasSuffix(s, suffix) {
- return s[:len(s)-len(suffix)], true
- }
- }
- return "", false
-}
-
-func parseLenDist(line string) (l uint32, d uint32, ok bool) {
- const (
- lStr = "len "
- dStr = "dist "
- )
- s := line
- if strings.HasPrefix(s, lStr) {
- s = s[len(lStr):]
- if l, s, ok := parseNum(s); ok && 3 <= l && l <= 258 {
- if strings.HasPrefix(s, dStr) {
- s = s[len(dStr):]
- if d, s, ok := parseNum(s); ok && 1 <= d && d <= 32768 && s == "" {
- return l, d, true
- }
- }
- }
- }
- return 0, 0, false
-}
-
-func parseNum(s string) (num uint32, remaining string, ok bool) {
- if i := strings.IndexByte(s, ' '); i >= 0 {
- s, remaining = s[:i], s[i+1:]
- for len(remaining) > 0 && remaining[0] == ' ' {
- remaining = remaining[1:]
- }
- }
-
- u, err := strconv.ParseUint(s, 10, 32)
- if err != nil {
- return 0, "", false
- }
- return uint32(u), remaining, true
-}
diff --git a/test/data/artificial/deflate-backref-crosses-blocks.deflate.make.txt b/test/data/artificial/deflate-backref-crosses-blocks.deflate.make-artificial.txt
similarity index 72%
rename from test/data/artificial/deflate-backref-crosses-blocks.deflate.make.txt
rename to test/data/artificial/deflate-backref-crosses-blocks.deflate.make-artificial.txt
index dfff0b1..67961db 100644
--- a/test/data/artificial/deflate-backref-crosses-blocks.deflate.make.txt
+++ b/test/data/artificial/deflate-backref-crosses-blocks.deflate.make-artificial.txt
@@ -1,4 +1,6 @@
-# Feed this file to script/make-deflate.go
+# Feed this file to script/make-artificial.go
+
+make deflate
blockNoCompression (nonFinal) {
literal "abcd"
diff --git a/test/data/artificial/deflate-distance-32768.deflate.make.txt b/test/data/artificial/deflate-distance-32768.deflate.make-artificial.txt
similarity index 87%
rename from test/data/artificial/deflate-distance-32768.deflate.make.txt
rename to test/data/artificial/deflate-distance-32768.deflate.make-artificial.txt
index a6ad239..277b6d0 100644
--- a/test/data/artificial/deflate-distance-32768.deflate.make.txt
+++ b/test/data/artificial/deflate-distance-32768.deflate.make-artificial.txt
@@ -1,4 +1,6 @@
-# Feed this file to script/make-deflate.go
+# Feed this file to script/make-artificial.go
+
+make deflate
blockFixedHuffman (final) {
# Make 16 + 126*258 + 244 = 32768 bytes:
diff --git a/test/data/artificial/gif-frame-out-of-bounds.gif b/test/data/artificial/gif-frame-out-of-bounds.gif
new file mode 100644
index 0000000..1a0b69f
--- /dev/null
+++ b/test/data/artificial/gif-frame-out-of-bounds.gif
Binary files differ
diff --git a/test/data/artificial/gif-frame-out-of-bounds.gif.make-artificial.txt b/test/data/artificial/gif-frame-out-of-bounds.gif.make-artificial.txt
new file mode 100644
index 0000000..741e165
--- /dev/null
+++ b/test/data/artificial/gif-frame-out-of-bounds.gif.make-artificial.txt
@@ -0,0 +1,91 @@
+# Feed this file to script/make-artificial.go
+
+# This GIF image contains three frames, each of which are outside the nominal
+# image's bounds: (0, 0) - (2, 2):
+#
+# - frame #0 has bounds (1, 0) - (4, 1).
+# - frame #1 has bounds (0, 1) - (2, 3).
+# - frame #2 has bounds (0, 4) - (1, 5).
+#
+# Here are some (but not all) possible decoding policies:
+#
+# 0. Reject it.
+# 1. Keep the image width×height at 2×2, clip all of the frames.
+# 2. Adjust the image width×height to 3×1, the first frame's size, move
+# frame #0's top-left to be (0, 0), and clip subsequent frames.
+# 3. Adjust the image width×height to 4×1, the first frame's bottom-right
+# corner, and clip subsequent frames.
+# 4. Expand the image width×height to 4×2, the union of the image and first
+# frame's bounds, and clip subsequent frames.
+# 5. Expand the image width×height to 4×5, so that no frames are clipped. This
+# needs to decode all frames before being able to report the image bounds.
+#
+# The GIF specification (https://www.w3.org/Graphics/GIF/spec-gif89a.txt) calls
+# for policy 0, rejection, as it says that "Each image must fit within the
+# boundaries of the Logical Screen, as defined in the Logical Screen
+# Descriptor". The spec uses "image" and "screen" for what Wuffs calls "frame"
+# and "image".
+#
+# In practice, real world encoders violate the spec, and real world decoders
+# have responded by accepting such files anyway. As of May 2018:
+#
+# - Chromium chooses policy 4:
+# https://cs.chromium.org/chromium/src/third_party/blink/renderer/platform/image-decoders/gif/gif_image_reader.cc?rcl=5161173c43324da2b13e1aa45bbe69901daa1279&l=740
+#
+# - Firefox chooses policy 2:
+# https://dxr.mozilla.org/mozilla-central/rev/b75acf9652937ce79a9bf02de843c100db0e5ec7/image/decoders/nsGIFDecoder2.cpp#814
+#
+# - Go chooses policy 0:
+# https://github.com/golang/go/blob/d3beea8c529a20b9eebb5ff8c22684af5ee1c920/src/image/gif/reader.go#L508
+# but a surprised user filed https://github.com/golang/go/issues/20856 when
+# Go rejected some (off-spec) GIF files that other decoders accept.
+#
+# - gdk-pixbuf chooses policy 1:
+# https://github.com/GNOME/gdk-pixbuf/blob/c1fd9f5d6592c0183c54efc806b3ca6871e1f496/gdk-pixbuf/io-gif.c#L992
+#
+# - giflib enforces no particular policy. It provides image and frame bounds
+# as encoded in the file and leaves it up to the caller how to respond.
+
+make gif
+
+header
+
+image {
+ imageWidthHeight 2 2
+ palette {
+ 0x00 0x00 0xFF
+ 0x11 0x00 0xFF
+ 0x22 0x00 0xFF
+ 0x33 0x00 0xFF
+ 0x44 0x00 0xFF
+ 0x55 0x00 0xFF
+ 0x66 0x00 0xFF
+ 0x77 0x00 0xFF
+
+ 0x00 0x88 0xFF
+ 0x00 0x99 0xFF
+ 0x00 0xAA 0xFF
+ 0x00 0xBB 0xFF
+ 0x00 0xCC 0xFF
+ 0x00 0xDD 0xFF
+ 0x00 0xEE 0xFF
+ 0x00 0xFF 0xFF
+ }
+}
+
+frame {
+ frameLeftTopWidthHeight 1 0 3 1
+}
+lzw 4 0x01 0x02 0x03
+
+frame {
+ frameLeftTopWidthHeight 0 1 2 2
+}
+lzw 4 0x08 0x09 0x0A 0x0B
+
+frame {
+ frameLeftTopWidthHeight 0 4 1 1
+}
+lzw 4 0x0E
+
+trailer
