diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..6a66aea --- /dev/null +++ b/LICENSE @@ -0,0 +1,27 @@ +Copyright (c) 2009 The Go Authors. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are +met: + + * Redistributions of source code must retain the above copyright +notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above +copyright notice, this list of conditions and the following disclaimer +in the documentation and/or other materials provided with the +distribution. + * Neither the name of Google Inc. nor the names of its +contributors may be used to endorse or promote products derived from +this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/README.md b/README.md new file mode 100644 index 0000000..0ba6214 --- /dev/null +++ b/README.md @@ -0,0 +1,3 @@ +Basic QR encoder. + +go get [-u] rsc.io/qr diff --git a/coding/gen.go b/coding/gen.go new file mode 100644 index 0000000..a3857f2 --- /dev/null +++ b/coding/gen.go @@ -0,0 +1,149 @@ +// +build ignore + +package main + +import "fmt" + +// tables from qrencode-3.1.1/qrspec.c + +var capacity = [41]struct { + width int + words int + remainder int + ec [4]int +}{ + {0, 0, 0, [4]int{0, 0, 0, 0}}, + {21, 26, 0, [4]int{7, 10, 13, 17}}, // 1 + {25, 44, 7, [4]int{10, 16, 22, 28}}, + {29, 70, 7, [4]int{15, 26, 36, 44}}, + {33, 100, 7, [4]int{20, 36, 52, 64}}, + {37, 134, 7, [4]int{26, 48, 72, 88}}, // 5 + {41, 172, 7, [4]int{36, 64, 96, 112}}, + {45, 196, 0, [4]int{40, 72, 108, 130}}, + {49, 242, 0, [4]int{48, 88, 132, 156}}, + {53, 292, 0, [4]int{60, 110, 160, 192}}, + {57, 346, 0, [4]int{72, 130, 192, 224}}, //10 + {61, 404, 0, [4]int{80, 150, 224, 264}}, + {65, 466, 0, [4]int{96, 176, 260, 308}}, + {69, 532, 0, [4]int{104, 198, 288, 352}}, + {73, 581, 3, [4]int{120, 216, 320, 384}}, + {77, 655, 3, [4]int{132, 240, 360, 432}}, //15 + {81, 733, 3, [4]int{144, 280, 408, 480}}, + {85, 815, 3, [4]int{168, 308, 448, 532}}, + {89, 901, 3, [4]int{180, 338, 504, 588}}, + {93, 991, 3, [4]int{196, 364, 546, 650}}, + {97, 1085, 3, [4]int{224, 416, 600, 700}}, //20 + {101, 1156, 4, [4]int{224, 442, 644, 750}}, + {105, 1258, 4, [4]int{252, 476, 690, 816}}, + {109, 1364, 4, [4]int{270, 504, 750, 900}}, + {113, 1474, 4, [4]int{300, 560, 810, 960}}, + {117, 1588, 4, [4]int{312, 588, 870, 1050}}, //25 + {121, 1706, 4, [4]int{336, 644, 952, 1110}}, + {125, 1828, 4, [4]int{360, 700, 1020, 1200}}, + {129, 1921, 3, [4]int{390, 728, 1050, 1260}}, + {133, 2051, 3, [4]int{420, 784, 1140, 1350}}, + {137, 2185, 3, [4]int{450, 812, 1200, 1440}}, //30 + {141, 2323, 3, [4]int{480, 868, 1290, 1530}}, + {145, 2465, 3, [4]int{510, 924, 1350, 1620}}, + {149, 2611, 3, [4]int{540, 980, 1440, 1710}}, + {153, 2761, 3, [4]int{570, 1036, 1530, 1800}}, + {157, 2876, 0, [4]int{570, 1064, 1590, 1890}}, //35 + {161, 3034, 0, [4]int{600, 1120, 1680, 1980}}, + {165, 3196, 0, [4]int{630, 1204, 1770, 2100}}, + {169, 3362, 0, [4]int{660, 1260, 1860, 2220}}, + {173, 3532, 0, [4]int{720, 1316, 1950, 2310}}, + {177, 3706, 0, [4]int{750, 1372, 2040, 2430}}, //40 +} + +var eccTable = [41][4][2]int{ + {{0, 0}, {0, 0}, {0, 0}, {0, 0}}, + {{1, 0}, {1, 0}, {1, 0}, {1, 0}}, // 1 + {{1, 0}, {1, 0}, {1, 0}, {1, 0}}, + {{1, 0}, {1, 0}, {2, 0}, {2, 0}}, + {{1, 0}, {2, 0}, {2, 0}, {4, 0}}, + {{1, 0}, {2, 0}, {2, 2}, {2, 2}}, // 5 + {{2, 0}, {4, 0}, {4, 0}, {4, 0}}, + {{2, 0}, {4, 0}, {2, 4}, {4, 1}}, + {{2, 0}, {2, 2}, {4, 2}, {4, 2}}, + {{2, 0}, {3, 2}, {4, 4}, {4, 4}}, + {{2, 2}, {4, 1}, {6, 2}, {6, 2}}, //10 + {{4, 0}, {1, 4}, {4, 4}, {3, 8}}, + {{2, 2}, {6, 2}, {4, 6}, {7, 4}}, + {{4, 0}, {8, 1}, {8, 4}, {12, 4}}, + {{3, 1}, {4, 5}, {11, 5}, {11, 5}}, + {{5, 1}, {5, 5}, {5, 7}, {11, 7}}, //15 + {{5, 1}, {7, 3}, {15, 2}, {3, 13}}, + {{1, 5}, {10, 1}, {1, 15}, {2, 17}}, + {{5, 1}, {9, 4}, {17, 1}, {2, 19}}, + {{3, 4}, {3, 11}, {17, 4}, {9, 16}}, + {{3, 5}, {3, 13}, {15, 5}, {15, 10}}, //20 + {{4, 4}, {17, 0}, {17, 6}, {19, 6}}, + {{2, 7}, {17, 0}, {7, 16}, {34, 0}}, + {{4, 5}, {4, 14}, {11, 14}, {16, 14}}, + {{6, 4}, {6, 14}, {11, 16}, {30, 2}}, + {{8, 4}, {8, 13}, {7, 22}, {22, 13}}, //25 + {{10, 2}, {19, 4}, {28, 6}, {33, 4}}, + {{8, 4}, {22, 3}, {8, 26}, {12, 28}}, + {{3, 10}, {3, 23}, {4, 31}, {11, 31}}, + {{7, 7}, {21, 7}, {1, 37}, {19, 26}}, + {{5, 10}, {19, 10}, {15, 25}, {23, 25}}, //30 + {{13, 3}, {2, 29}, {42, 1}, {23, 28}}, + {{17, 0}, {10, 23}, {10, 35}, {19, 35}}, + {{17, 1}, {14, 21}, {29, 19}, {11, 46}}, + {{13, 6}, {14, 23}, {44, 7}, {59, 1}}, + {{12, 7}, {12, 26}, {39, 14}, {22, 41}}, //35 + {{6, 14}, {6, 34}, {46, 10}, {2, 64}}, + {{17, 4}, {29, 14}, {49, 10}, {24, 46}}, + {{4, 18}, {13, 32}, {48, 14}, {42, 32}}, + {{20, 4}, {40, 7}, {43, 22}, {10, 67}}, + {{19, 6}, {18, 31}, {34, 34}, {20, 61}}, //40 +} + +var align = [41][2]int{ + {0, 0}, + {0, 0}, {18, 0}, {22, 0}, {26, 0}, {30, 0}, // 1- 5 + {34, 0}, {22, 38}, {24, 42}, {26, 46}, {28, 50}, // 6-10 + {30, 54}, {32, 58}, {34, 62}, {26, 46}, {26, 48}, //11-15 + {26, 50}, {30, 54}, {30, 56}, {30, 58}, {34, 62}, //16-20 + {28, 50}, {26, 50}, {30, 54}, {28, 54}, {32, 58}, //21-25 + {30, 58}, {34, 62}, {26, 50}, {30, 54}, {26, 52}, //26-30 + {30, 56}, {34, 60}, {30, 58}, {34, 62}, {30, 54}, //31-35 + {24, 50}, {28, 54}, {32, 58}, {26, 54}, {30, 58}, //35-40 +} + +var versionPattern = [41]int{ + 0, + 0, 0, 0, 0, 0, 0, + 0x07c94, 0x085bc, 0x09a99, 0x0a4d3, 0x0bbf6, 0x0c762, 0x0d847, 0x0e60d, + 0x0f928, 0x10b78, 0x1145d, 0x12a17, 0x13532, 0x149a6, 0x15683, 0x168c9, + 0x177ec, 0x18ec4, 0x191e1, 0x1afab, 0x1b08e, 0x1cc1a, 0x1d33f, 0x1ed75, + 0x1f250, 0x209d5, 0x216f0, 0x228ba, 0x2379f, 0x24b0b, 0x2542e, 0x26a64, + 0x27541, 0x28c69, +} + +func main() { + fmt.Printf("\t{},\n") + for i := 1; i <= 40; i++ { + apos := align[i][0] - 2 + if apos < 0 { + apos = 100 + } + astride := align[i][1] - align[i][0] + if astride < 1 { + astride = 100 + } + fmt.Printf("\t{%v, %v, %v, %#x, [4]level{{%v, %v}, {%v, %v}, {%v, %v}, {%v, %v}}}, // %v\n", + apos, astride, capacity[i].words, + versionPattern[i], + eccTable[i][0][0]+eccTable[i][0][1], + float64(capacity[i].ec[0])/float64(eccTable[i][0][0]+eccTable[i][0][1]), + eccTable[i][1][0]+eccTable[i][1][1], + float64(capacity[i].ec[1])/float64(eccTable[i][1][0]+eccTable[i][1][1]), + eccTable[i][2][0]+eccTable[i][2][1], + float64(capacity[i].ec[2])/float64(eccTable[i][2][0]+eccTable[i][2][1]), + eccTable[i][3][0]+eccTable[i][3][1], + float64(capacity[i].ec[3])/float64(eccTable[i][3][0]+eccTable[i][3][1]), + i, + ) + } +} diff --git a/coding/qr.go b/coding/qr.go new file mode 100644 index 0000000..4aa5288 --- /dev/null +++ b/coding/qr.go @@ -0,0 +1,815 @@ +// Copyright 2011 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 coding implements low-level QR coding details. +package coding + +import ( + "fmt" + "strconv" + "strings" + + "rsc.io/qr/gf256" +) + +// Field is the field for QR error correction. +var Field = gf256.NewField(0x11d, 2) + +// A Version represents a QR version. +// The version specifies the size of the QR code: +// a QR code with version v has 4v+17 pixels on a side. +// Versions number from 1 to 40: the larger the version, +// the more information the code can store. +type Version int + +const MinVersion = 1 +const MaxVersion = 40 + +func (v Version) String() string { + return strconv.Itoa(int(v)) +} + +func (v Version) sizeClass() int { + if v <= 9 { + return 0 + } + if v <= 26 { + return 1 + } + return 2 +} + +// DataBytes returns the number of data bytes that can be +// stored in a QR code with the given version and level. +func (v Version) DataBytes(l Level) int { + vt := &vtab[v] + lev := &vt.level[l] + return vt.bytes - lev.nblock*lev.check +} + +// Encoding implements a QR data encoding scheme. +// The implementations--Numeric, Alphanumeric, and String--specify +// the character set and the mapping from UTF-8 to code bits. +// The more restrictive the mode, the fewer code bits are needed. +type Encoding interface { + Check() error + Bits(v Version) int + Encode(b *Bits, v Version) +} + +type Bits struct { + b []byte + nbit int +} + +func (b *Bits) Reset() { + b.b = b.b[:0] + b.nbit = 0 +} + +func (b *Bits) Bits() int { + return b.nbit +} + +func (b *Bits) Bytes() []byte { + if b.nbit%8 != 0 { + panic("fractional byte") + } + return b.b +} + +func (b *Bits) Append(p []byte) { + if b.nbit%8 != 0 { + panic("fractional byte") + } + b.b = append(b.b, p...) + b.nbit += 8 * len(p) +} + +func (b *Bits) Write(v uint, nbit int) { + for nbit > 0 { + n := nbit + if n > 8 { + n = 8 + } + if b.nbit%8 == 0 { + b.b = append(b.b, 0) + } else { + m := -b.nbit & 7 + if n > m { + n = m + } + } + b.nbit += n + sh := uint(nbit - n) + b.b[len(b.b)-1] |= uint8(v >> sh << uint(-b.nbit&7)) + v -= v >> sh << sh + nbit -= n + } +} + +// Num is the encoding for numeric data. +// The only valid characters are the decimal digits 0 through 9. +type Num string + +func (s Num) String() string { + return fmt.Sprintf("Num(%#q)", string(s)) +} + +func (s Num) Check() error { + for _, c := range s { + if c < '0' || '9' < c { + return fmt.Errorf("non-numeric string %#q", string(s)) + } + } + return nil +} + +var numLen = [3]int{10, 12, 14} + +func (s Num) Bits(v Version) int { + return 4 + numLen[v.sizeClass()] + (10*len(s)+2)/3 +} + +func (s Num) Encode(b *Bits, v Version) { + b.Write(1, 4) + b.Write(uint(len(s)), numLen[v.sizeClass()]) + var i int + for i = 0; i+3 <= len(s); i += 3 { + w := uint(s[i]-'0')*100 + uint(s[i+1]-'0')*10 + uint(s[i+2]-'0') + b.Write(w, 10) + } + switch len(s) - i { + case 1: + w := uint(s[i] - '0') + b.Write(w, 4) + case 2: + w := uint(s[i]-'0')*10 + uint(s[i+1]-'0') + b.Write(w, 7) + } +} + +// Alpha is the encoding for alphanumeric data. +// The valid characters are 0-9A-Z$%*+-./: and space. +type Alpha string + +const alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:" + +func (s Alpha) String() string { + return fmt.Sprintf("Alpha(%#q)", string(s)) +} + +func (s Alpha) Check() error { + for _, c := range s { + if strings.IndexRune(alphabet, c) < 0 { + return fmt.Errorf("non-alphanumeric string %#q", string(s)) + } + } + return nil +} + +var alphaLen = [3]int{9, 11, 13} + +func (s Alpha) Bits(v Version) int { + return 4 + alphaLen[v.sizeClass()] + (11*len(s)+1)/2 +} + +func (s Alpha) Encode(b *Bits, v Version) { + b.Write(2, 4) + b.Write(uint(len(s)), alphaLen[v.sizeClass()]) + var i int + for i = 0; i+2 <= len(s); i += 2 { + w := uint(strings.IndexRune(alphabet, rune(s[i])))*45 + + uint(strings.IndexRune(alphabet, rune(s[i+1]))) + b.Write(w, 11) + } + + if i < len(s) { + w := uint(strings.IndexRune(alphabet, rune(s[i]))) + b.Write(w, 6) + } +} + +// String is the encoding for 8-bit data. All bytes are valid. +type String string + +func (s String) String() string { + return fmt.Sprintf("String(%#q)", string(s)) +} + +func (s String) Check() error { + return nil +} + +var stringLen = [3]int{8, 16, 16} + +func (s String) Bits(v Version) int { + return 4 + stringLen[v.sizeClass()] + 8*len(s) +} + +func (s String) Encode(b *Bits, v Version) { + b.Write(4, 4) + b.Write(uint(len(s)), stringLen[v.sizeClass()]) + for i := 0; i < len(s); i++ { + b.Write(uint(s[i]), 8) + } +} + +// A Pixel describes a single pixel in a QR code. +type Pixel uint32 + +const ( + Black Pixel = 1 << iota + Invert +) + +func (p Pixel) Offset() uint { + return uint(p >> 6) +} + +func OffsetPixel(o uint) Pixel { + return Pixel(o << 6) +} + +func (r PixelRole) Pixel() Pixel { + return Pixel(r << 2) +} + +func (p Pixel) Role() PixelRole { + return PixelRole(p>>2) & 15 +} + +func (p Pixel) String() string { + s := p.Role().String() + if p&Black != 0 { + s += "+black" + } + if p&Invert != 0 { + s += "+invert" + } + s += "+" + strconv.FormatUint(uint64(p.Offset()), 10) + return s +} + +// A PixelRole describes the role of a QR pixel. +type PixelRole uint32 + +const ( + _ PixelRole = iota + Position // position squares (large) + Alignment // alignment squares (small) + Timing // timing strip between position squares + Format // format metadata + PVersion // version pattern + Unused // unused pixel + Data // data bit + Check // error correction check bit + Extra +) + +var roles = []string{ + "", + "position", + "alignment", + "timing", + "format", + "pversion", + "unused", + "data", + "check", + "extra", +} + +func (r PixelRole) String() string { + if Position <= r && r <= Check { + return roles[r] + } + return strconv.Itoa(int(r)) +} + +// A Level represents a QR error correction level. +// From least to most tolerant of errors, they are L, M, Q, H. +type Level int + +const ( + L Level = iota + M + Q + H +) + +func (l Level) String() string { + if L <= l && l <= H { + return "LMQH"[l : l+1] + } + return strconv.Itoa(int(l)) +} + +// A Code is a square pixel grid. +type Code struct { + Bitmap []byte // 1 is black, 0 is white + Size int // number of pixels on a side + Stride int // number of bytes per row +} + +func (c *Code) Black(x, y int) bool { + return 0 <= x && x < c.Size && 0 <= y && y < c.Size && + c.Bitmap[y*c.Stride+x/8]&(1<= pad { + break + } + b.Write(0x11, 8) + } + } +} + +func (b *Bits) AddCheckBytes(v Version, l Level) { + nd := v.DataBytes(l) + if b.nbit < nd*8 { + b.Pad(nd*8 - b.nbit) + } + if b.nbit != nd*8 { + panic("qr: too much data") + } + + dat := b.Bytes() + vt := &vtab[v] + lev := &vt.level[l] + db := nd / lev.nblock + extra := nd % lev.nblock + chk := make([]byte, lev.check) + rs := gf256.NewRSEncoder(Field, lev.check) + for i := 0; i < lev.nblock; i++ { + if i == lev.nblock-extra { + db++ + } + rs.ECC(dat[:db], chk) + b.Append(chk) + dat = dat[db:] + } + + if len(b.Bytes()) != vt.bytes { + panic("qr: internal error") + } +} + +func (p *Plan) Encode(text ...Encoding) (*Code, error) { + var b Bits + for _, t := range text { + if err := t.Check(); err != nil { + return nil, err + } + t.Encode(&b, p.Version) + } + if b.Bits() > p.DataBytes*8 { + return nil, fmt.Errorf("cannot encode %d bits into %d-bit code", b.Bits(), p.DataBytes*8) + } + b.AddCheckBytes(p.Version, p.Level) + bytes := b.Bytes() + + // Now we have the checksum bytes and the data bytes. + // Construct the actual code. + c := &Code{Size: len(p.Pixel), Stride: (len(p.Pixel) + 7) &^ 7} + c.Bitmap = make([]byte, c.Stride*c.Size) + crow := c.Bitmap + for _, row := range p.Pixel { + for x, pix := range row { + switch pix.Role() { + case Data, Check: + o := pix.Offset() + if bytes[o/8]&(1< 40 { + return nil, fmt.Errorf("invalid QR version %d", int(v)) + } + siz := 17 + int(v)*4 + m := grid(siz) + p.Pixel = m + + // Timing markers (overwritten by boxes). + const ti = 6 // timing is in row/column 6 (counting from 0) + for i := range m { + p := Timing.Pixel() + if i&1 == 0 { + p |= Black + } + m[i][ti] = p + m[ti][i] = p + } + + // Position boxes. + posBox(m, 0, 0) + posBox(m, siz-7, 0) + posBox(m, 0, siz-7) + + // Alignment boxes. + info := &vtab[v] + for x := 4; x+5 < siz; { + for y := 4; y+5 < siz; { + // don't overwrite timing markers + if (x < 7 && y < 7) || (x < 7 && y+5 >= siz-7) || (x+5 >= siz-7 && y < 7) { + } else { + alignBox(m, x, y) + } + if y == 4 { + y = info.apos + } else { + y += info.astride + } + } + if x == 4 { + x = info.apos + } else { + x += info.astride + } + } + + // Version pattern. + pat := vtab[v].pattern + if pat != 0 { + v := pat + for x := 0; x < 6; x++ { + for y := 0; y < 3; y++ { + p := PVersion.Pixel() + if v&1 != 0 { + p |= Black + } + m[siz-11+y][x] = p + m[x][siz-11+y] = p + v >>= 1 + } + } + } + + // One lonely black pixel + m[siz-8][8] = Unused.Pixel() | Black + + return p, nil +} + +// fplan adds the format pixels +func fplan(l Level, m Mask, p *Plan) error { + // Format pixels. + fb := uint32(l^1) << 13 // level: L=01, M=00, Q=11, H=10 + fb |= uint32(m) << 10 // mask + const formatPoly = 0x537 + rem := fb + for i := 14; i >= 10; i-- { + if rem&(1<>i)&1 == 1 { + pix |= Black + } + if (invert>>i)&1 == 1 { + pix ^= Invert | Black + } + // top left + switch { + case i < 6: + p.Pixel[i][8] = pix + case i < 8: + p.Pixel[i+1][8] = pix + case i < 9: + p.Pixel[8][7] = pix + default: + p.Pixel[8][14-i] = pix + } + // bottom right + switch { + case i < 8: + p.Pixel[8][siz-1-int(i)] = pix + default: + p.Pixel[siz-1-int(14-i)][8] = pix + } + } + return nil +} + +// lplan edits a version-only Plan to add information +// about the error correction levels. +func lplan(v Version, l Level, p *Plan) error { + p.Level = l + + nblock := vtab[v].level[l].nblock + ne := vtab[v].level[l].check + nde := (vtab[v].bytes - ne*nblock) / nblock + extra := (vtab[v].bytes - ne*nblock) % nblock + dataBits := (nde*nblock + extra) * 8 + checkBits := ne * nblock * 8 + + p.DataBytes = vtab[v].bytes - ne*nblock + p.CheckBytes = ne * nblock + p.Blocks = nblock + + // Make data + checksum pixels. + data := make([]Pixel, dataBits) + for i := range data { + data[i] = Data.Pixel() | OffsetPixel(uint(i)) + } + check := make([]Pixel, checkBits) + for i := range check { + check[i] = Check.Pixel() | OffsetPixel(uint(i+dataBits)) + } + + // Split into blocks. + dataList := make([][]Pixel, nblock) + checkList := make([][]Pixel, nblock) + for i := 0; i < nblock; i++ { + // The last few blocks have an extra data byte (8 pixels). + nd := nde + if i >= nblock-extra { + nd++ + } + dataList[i], data = data[0:nd*8], data[nd*8:] + checkList[i], check = check[0:ne*8], check[ne*8:] + } + if len(data) != 0 || len(check) != 0 { + panic("data/check math") + } + + // Build up bit sequence, taking first byte of each block, + // then second byte, and so on. Then checksums. + bits := make([]Pixel, dataBits+checkBits) + dst := bits + for i := 0; i < nde+1; i++ { + for _, b := range dataList { + if i*8 < len(b) { + copy(dst, b[i*8:(i+1)*8]) + dst = dst[8:] + } + } + } + for i := 0; i < ne; i++ { + for _, b := range checkList { + if i*8 < len(b) { + copy(dst, b[i*8:(i+1)*8]) + dst = dst[8:] + } + } + } + if len(dst) != 0 { + panic("dst math") + } + + // Sweep up pair of columns, + // then down, assigning to right then left pixel. + // Repeat. + // See Figure 2 of http://www.pclviewer.com/rs2/qrtopology.htm + siz := len(p.Pixel) + rem := make([]Pixel, 7) + for i := range rem { + rem[i] = Extra.Pixel() + } + src := append(bits, rem...) + for x := siz; x > 0; { + for y := siz - 1; y >= 0; y-- { + if p.Pixel[y][x-1].Role() == 0 { + p.Pixel[y][x-1], src = src[0], src[1:] + } + if p.Pixel[y][x-2].Role() == 0 { + p.Pixel[y][x-2], src = src[0], src[1:] + } + } + x -= 2 + if x == 7 { // vertical timing strip + x-- + } + for y := 0; y < siz; y++ { + if p.Pixel[y][x-1].Role() == 0 { + p.Pixel[y][x-1], src = src[0], src[1:] + } + if p.Pixel[y][x-2].Role() == 0 { + p.Pixel[y][x-2], src = src[0], src[1:] + } + } + x -= 2 + } + return nil +} + +// mplan edits a version+level-only Plan to add the mask. +func mplan(m Mask, p *Plan) error { + p.Mask = m + for y, row := range p.Pixel { + for x, pix := range row { + if r := pix.Role(); (r == Data || r == Check || r == Extra) && p.Mask.Invert(y, x) { + row[x] ^= Black | Invert + } + } + } + return nil +} + +// posBox draws a position (large) box at upper left x, y. +func posBox(m [][]Pixel, x, y int) { + pos := Position.Pixel() + // box + for dy := 0; dy < 7; dy++ { + for dx := 0; dx < 7; dx++ { + p := pos + if dx == 0 || dx == 6 || dy == 0 || dy == 6 || 2 <= dx && dx <= 4 && 2 <= dy && dy <= 4 { + p |= Black + } + m[y+dy][x+dx] = p + } + } + // white border + for dy := -1; dy < 8; dy++ { + if 0 <= y+dy && y+dy < len(m) { + if x > 0 { + m[y+dy][x-1] = pos + } + if x+7 < len(m) { + m[y+dy][x+7] = pos + } + } + } + for dx := -1; dx < 8; dx++ { + if 0 <= x+dx && x+dx < len(m) { + if y > 0 { + m[y-1][x+dx] = pos + } + if y+7 < len(m) { + m[y+7][x+dx] = pos + } + } + } +} + +// alignBox draw an alignment (small) box at upper left x, y. +func alignBox(m [][]Pixel, x, y int) { + // box + align := Alignment.Pixel() + for dy := 0; dy < 5; dy++ { + for dx := 0; dx < 5; dx++ { + p := align + if dx == 0 || dx == 4 || dy == 0 || dy == 4 || dx == 2 && dy == 2 { + p |= Black + } + m[y+dy][x+dx] = p + } + } +} diff --git a/coding/qr_test.go b/coding/qr_test.go new file mode 100644 index 0000000..c933bb8 --- /dev/null +++ b/coding/qr_test.go @@ -0,0 +1,133 @@ +// Copyright 2011 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 coding + +import ( + "bytes" + "testing" + + "rsc.io/qr/gf256" + "rsc.io/qr/libqrencode" +) + +func test(t *testing.T, v Version, l Level, text ...Encoding) bool { + s := "" + ty := libqrencode.EightBit + switch x := text[0].(type) { + case String: + s = string(x) + case Alpha: + s = string(x) + ty = libqrencode.Alphanumeric + case Num: + s = string(x) + ty = libqrencode.Numeric + } + key, err := libqrencode.Encode(libqrencode.Version(v), libqrencode.Level(l), ty, s) + if err != nil { + t.Errorf("libqrencode.Encode(%v, %v, %d, %#q): %v", v, l, ty, s, err) + return false + } + mask := (^key.Pixel[8][2]&1)<<2 | (key.Pixel[8][3]&1)<<1 | (^key.Pixel[8][4] & 1) + p, err := NewPlan(v, l, Mask(mask)) + if err != nil { + t.Errorf("NewPlan(%v, L, %d): %v", v, err, mask) + return false + } + if len(p.Pixel) != len(key.Pixel) { + t.Errorf("%v: NewPlan uses %dx%d, libqrencode uses %dx%d", v, len(p.Pixel), len(p.Pixel), len(key.Pixel), len(key.Pixel)) + return false + } + c, err := p.Encode(text...) + if err != nil { + t.Errorf("Encode: %v", err) + return false + } + badpix := 0 +Pixel: + for y, prow := range p.Pixel { + for x, pix := range prow { + pix &^= Black + if c.Black(x, y) { + pix |= Black + } + + keypix := key.Pixel[y][x] + want := Pixel(0) + switch { + case keypix&libqrencode.Finder != 0: + want = Position.Pixel() + case keypix&libqrencode.Alignment != 0: + want = Alignment.Pixel() + case keypix&libqrencode.Timing != 0: + want = Timing.Pixel() + case keypix&libqrencode.Format != 0: + want = Format.Pixel() + want |= OffsetPixel(pix.Offset()) // sic + want |= pix & Invert + case keypix&libqrencode.PVersion != 0: + want = PVersion.Pixel() + case keypix&libqrencode.DataECC != 0: + if pix.Role() == Check || pix.Role() == Extra { + want = pix.Role().Pixel() + } else { + want = Data.Pixel() + } + want |= OffsetPixel(pix.Offset()) + want |= pix & Invert + default: + want = Unused.Pixel() + } + if keypix&libqrencode.Black != 0 { + want |= Black + } + if pix != want { + t.Errorf("%v/%v: Pixel[%d][%d] = %v, want %v %#x", v, mask, y, x, pix, want, keypix) + if badpix++; badpix >= 100 { + t.Errorf("stopping after %d bad pixels", badpix) + break Pixel + } + } + } + } + return badpix == 0 +} + +var input = []Encoding{ + String("hello"), + Num("1"), + Num("12"), + Num("123"), + Alpha("AB"), + Alpha("ABC"), +} + +func TestVersion(t *testing.T) { + badvers := 0 +Version: + for v := Version(1); v <= 40; v++ { + for l := L; l <= H; l++ { + for _, in := range input { + if !test(t, v, l, in) { + if badvers++; badvers >= 10 { + t.Errorf("stopping after %d bad versions", badvers) + break Version + } + } + } + } + } +} + +func TestEncode(t *testing.T) { + data := []byte{0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11} + check := []byte{0xa5, 0x24, 0xd4, 0xc1, 0xed, 0x36, 0xc7, 0x87, 0x2c, 0x55} + rs := gf256.NewRSEncoder(Field, len(check)) + out := make([]byte, len(check)) + rs.ECC(data, out) + if !bytes.Equal(out, check) { + t.Errorf("have %x want %x", out, check) + } +} diff --git a/gf256/blog_test.go b/gf256/blog_test.go new file mode 100644 index 0000000..4fbf7ec --- /dev/null +++ b/gf256/blog_test.go @@ -0,0 +1,85 @@ +// Copyright 2012 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 file contains a straightforward implementation of +// Reed-Solomon encoding, along with a benchmark. +// It goes with http://research.swtch.com/field. +// +// For an optimized implementation, see gf256.go. + +package gf256 + +import ( + "bytes" + "fmt" + "testing" +) + +// BlogECC writes to check the error correcting code bytes +// for data using the given Reed-Solomon parameters. +func BlogECC(rs *RSEncoder, m []byte, check []byte) { + if len(check) < rs.c { + panic("gf256: invalid check byte length") + } + if rs.c == 0 { + return + } + + // The check bytes are the remainder after dividing + // data padded with c zeros by the generator polynomial. + + // p = data padded with c zeros. + var p []byte + n := len(m) + rs.c + if len(rs.p) >= n { + p = rs.p + } else { + p = make([]byte, n) + } + copy(p, m) + for i := len(m); i < len(p); i++ { + p[i] = 0 + } + + gen := rs.gen + + // Divide p by gen, leaving the remainder in p[len(data):]. + // p[0] is the most significant term in p, and + // gen[0] is the most significant term in the generator. + for i := 0; i < len(m); i++ { + k := f.Mul(p[i], f.Inv(gen[0])) // k = pi / g0 + // p -= k·g + for j, g := range gen { + p[i+j] = f.Add(p[i+j], f.Mul(k, g)) + } + } + + copy(check, p[len(m):]) + rs.p = p +} + +func BenchmarkBlogECC(b *testing.B) { + data := []byte{0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11} + check := []byte{0x29, 0x41, 0xb3, 0x93, 0x8, 0xe8, 0xa3, 0xe7, 0x63, 0x8f} + out := make([]byte, len(check)) + rs := NewRSEncoder(f, len(check)) + for i := 0; i < b.N; i++ { + BlogECC(rs, data, out) + } + b.SetBytes(int64(len(data))) + if !bytes.Equal(out, check) { + fmt.Printf("have %#v want %#v\n", out, check) + } +} + +func TestBlogECC(t *testing.T) { + data := []byte{0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11} + check := []byte{0xa5, 0x24, 0xd4, 0xc1, 0xed, 0x36, 0xc7, 0x87, 0x2c, 0x55} + out := make([]byte, len(check)) + rs := NewRSEncoder(f, len(check)) + BlogECC(rs, data, out) + if !bytes.Equal(out, check) { + t.Errorf("have %x want %x", out, check) + } +} diff --git a/gf256/gf256.go b/gf256/gf256.go new file mode 100644 index 0000000..bfeeeb3 --- /dev/null +++ b/gf256/gf256.go @@ -0,0 +1,241 @@ +// Copyright 2010 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 gf256 implements arithmetic over the Galois Field GF(256). +package gf256 + +import "strconv" + +// A Field represents an instance of GF(256) defined by a specific polynomial. +type Field struct { + log [256]byte // log[0] is unused + exp [510]byte +} + +// NewField returns a new field corresponding to the polynomial poly +// and generator α. The Reed-Solomon encoding in QR codes uses +// polynomial 0x11d with generator 2. +// +// The choice of generator α only affects the Exp and Log operations. +func NewField(poly, α int) *Field { + if poly < 0x100 || poly >= 0x200 || reducible(poly) { + panic("gf256: invalid polynomial: " + strconv.Itoa(poly)) + } + + var f Field + x := 1 + for i := 0; i < 255; i++ { + if x == 1 && i != 0 { + panic("gf256: invalid generator " + strconv.Itoa(α) + + " for polynomial " + strconv.Itoa(poly)) + } + f.exp[i] = byte(x) + f.exp[i+255] = byte(x) + f.log[x] = byte(i) + x = mul(x, α, poly) + } + f.log[0] = 255 + for i := 0; i < 255; i++ { + if f.log[f.exp[i]] != byte(i) { + panic("bad log") + } + if f.log[f.exp[i+255]] != byte(i) { + panic("bad log") + } + } + for i := 1; i < 256; i++ { + if f.exp[f.log[i]] != byte(i) { + panic("bad log") + } + } + + return &f +} + +// nbit returns the number of significant in p. +func nbit(p int) uint { + n := uint(0) + for ; p > 0; p >>= 1 { + n++ + } + return n +} + +// polyDiv divides the polynomial p by q and returns the remainder. +func polyDiv(p, q int) int { + np := nbit(p) + nq := nbit(q) + for ; np >= nq; np-- { + if p&(1<<(np-1)) != 0 { + p ^= q << (np - nq) + } + } + return p +} + +// mul returns the product x*y mod poly, a GF(256) multiplication. +func mul(x, y, poly int) int { + z := 0 + for x > 0 { + if x&1 != 0 { + z ^= y + } + x >>= 1 + y <<= 1 + if y&0x100 != 0 { + y ^= poly + } + } + return z +} + +// reducible reports whether p is reducible. +func reducible(p int) bool { + // Multiplying n-bit * n-bit produces (2n-1)-bit, + // so if p is reducible, one of its factors must be + // of np/2+1 bits or fewer. + np := nbit(p) + for q := 2; q < 1<<(np/2+1); q++ { + if polyDiv(p, q) == 0 { + return true + } + } + return false +} + +// Add returns the sum of x and y in the field. +func (f *Field) Add(x, y byte) byte { + return x ^ y +} + +// Exp returns the base-α exponential of e in the field. +// If e < 0, Exp returns 0. +func (f *Field) Exp(e int) byte { + if e < 0 { + return 0 + } + return f.exp[e%255] +} + +// Log returns the base-α logarithm of x in the field. +// If x == 0, Log returns -1. +func (f *Field) Log(x byte) int { + if x == 0 { + return -1 + } + return int(f.log[x]) +} + +// Inv returns the multiplicative inverse of x in the field. +// If x == 0, Inv returns 0. +func (f *Field) Inv(x byte) byte { + if x == 0 { + return 0 + } + return f.exp[255-f.log[x]] +} + +// Mul returns the product of x and y in the field. +func (f *Field) Mul(x, y byte) byte { + if x == 0 || y == 0 { + return 0 + } + return f.exp[int(f.log[x])+int(f.log[y])] +} + +// An RSEncoder implements Reed-Solomon encoding +// over a given field using a given number of error correction bytes. +type RSEncoder struct { + f *Field + c int + gen []byte + lgen []byte + p []byte +} + +func (f *Field) gen(e int) (gen, lgen []byte) { + // p = 1 + p := make([]byte, e+1) + p[e] = 1 + + for i := 0; i < e; i++ { + // p *= (x + Exp(i)) + // p[j] = p[j]*Exp(i) + p[j+1]. + c := f.Exp(i) + for j := 0; j < e; j++ { + p[j] = f.Mul(p[j], c) ^ p[j+1] + } + p[e] = f.Mul(p[e], c) + } + + // lp = log p. + lp := make([]byte, e+1) + for i, c := range p { + if c == 0 { + lp[i] = 255 + } else { + lp[i] = byte(f.Log(c)) + } + } + + return p, lp +} + +// NewRSEncoder returns a new Reed-Solomon encoder +// over the given field and number of error correction bytes. +func NewRSEncoder(f *Field, c int) *RSEncoder { + gen, lgen := f.gen(c) + return &RSEncoder{f: f, c: c, gen: gen, lgen: lgen} +} + +// ECC writes to check the error correcting code bytes +// for data using the given Reed-Solomon parameters. +func (rs *RSEncoder) ECC(data []byte, check []byte) { + if len(check) < rs.c { + panic("gf256: invalid check byte length") + } + if rs.c == 0 { + return + } + + // The check bytes are the remainder after dividing + // data padded with c zeros by the generator polynomial. + + // p = data padded with c zeros. + var p []byte + n := len(data) + rs.c + if len(rs.p) >= n { + p = rs.p + } else { + p = make([]byte, n) + } + copy(p, data) + for i := len(data); i < len(p); i++ { + p[i] = 0 + } + + // Divide p by gen, leaving the remainder in p[len(data):]. + // p[0] is the most significant term in p, and + // gen[0] is the most significant term in the generator, + // which is always 1. + // To avoid repeated work, we store various values as + // lv, not v, where lv = log[v]. + f := rs.f + lgen := rs.lgen[1:] + for i := 0; i < len(data); i++ { + c := p[i] + if c == 0 { + continue + } + q := p[i+1:] + exp := f.exp[f.log[c]:] + for j, lg := range lgen { + if lg != 255 { // lgen uses 255 for log 0 + q[j] ^= exp[lg] + } + } + } + copy(check, p[len(data):]) + rs.p = p +} diff --git a/gf256/gf256_test.go b/gf256/gf256_test.go new file mode 100644 index 0000000..f77fa7d --- /dev/null +++ b/gf256/gf256_test.go @@ -0,0 +1,194 @@ +// Copyright 2010 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 gf256 + +import ( + "bytes" + "fmt" + "testing" +) + +var f = NewField(0x11d, 2) // x^8 + x^4 + x^3 + x^2 + 1 + +func TestBasic(t *testing.T) { + if f.Exp(0) != 1 || f.Exp(1) != 2 || f.Exp(255) != 1 { + panic("bad Exp") + } +} + +func TestECC(t *testing.T) { + data := []byte{0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11} + check := []byte{0xa5, 0x24, 0xd4, 0xc1, 0xed, 0x36, 0xc7, 0x87, 0x2c, 0x55} + out := make([]byte, len(check)) + rs := NewRSEncoder(f, len(check)) + rs.ECC(data, out) + if !bytes.Equal(out, check) { + t.Errorf("have %x want %x", out, check) + } +} + +func TestLinear(t *testing.T) { + d1 := []byte{0x00, 0x00} + c1 := []byte{0x00, 0x00} + out := make([]byte, len(c1)) + rs := NewRSEncoder(f, len(c1)) + if rs.ECC(d1, out); !bytes.Equal(out, c1) { + t.Errorf("ECBytes(%x, %d) = %x, want 0", d1, len(c1), out) + } + d2 := []byte{0x00, 0x01} + c2 := make([]byte, 2) + rs.ECC(d2, c2) + d3 := []byte{0x00, 0x02} + c3 := make([]byte, 2) + rs.ECC(d3, c3) + cx := make([]byte, 2) + for i := range cx { + cx[i] = c2[i] ^ c3[i] + } + d4 := []byte{0x00, 0x03} + c4 := make([]byte, 2) + rs.ECC(d4, c4) + if !bytes.Equal(cx, c4) { + t.Errorf("ECBytes(%x, 2) = %x\nECBytes(%x, 2) = %x\nxor = %x\nECBytes(%x, 2) = %x", + d2, c2, d3, c3, cx, d4, c4) + } +} + +func TestGaussJordan(t *testing.T) { + rs := NewRSEncoder(f, 2) + m := make([][]byte, 16) + for i := range m { + m[i] = make([]byte, 4) + m[i][i/8] = 1 << uint(i%8) + rs.ECC(m[i][:2], m[i][2:]) + } + if false { + fmt.Printf("---\n") + for _, row := range m { + fmt.Printf("%x\n", row) + } + } + b := []uint{0, 1, 2, 3, 12, 13, 14, 15, 20, 21, 22, 23, 24, 25, 26, 27} + for i := 0; i < 16; i++ { + bi := b[i] + if m[i][bi/8]&(1<<(7-bi%8)) == 0 { + for j := i + 1; ; j++ { + if j >= len(m) { + t.Errorf("lost track for %d", bi) + break + } + if m[j][bi/8]&(1<<(7-bi%8)) != 0 { + m[i], m[j] = m[j], m[i] + break + } + } + } + for j := i + 1; j < len(m); j++ { + if m[j][bi/8]&(1<<(7-bi%8)) != 0 { + for k := range m[j] { + m[j][k] ^= m[i][k] + } + } + } + } + if false { + fmt.Printf("---\n") + for _, row := range m { + fmt.Printf("%x\n", row) + } + } + for i := 15; i >= 0; i-- { + bi := b[i] + for j := i - 1; j >= 0; j-- { + if m[j][bi/8]&(1<<(7-bi%8)) != 0 { + for k := range m[j] { + m[j][k] ^= m[i][k] + } + } + } + } + if false { + fmt.Printf("---\n") + for _, row := range m { + fmt.Printf("%x", row) + out := make([]byte, 2) + if rs.ECC(row[:2], out); !bytes.Equal(out, row[2:]) { + fmt.Printf(" - want %x", out) + } + fmt.Printf("\n") + } + } +} + +func BenchmarkECC(b *testing.B) { + data := []byte{0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0x10, 0x20, 0x0c, 0x56, 0x61, 0x80, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11, 0xec, 0x11} + check := []byte{0x29, 0x41, 0xb3, 0x93, 0x8, 0xe8, 0xa3, 0xe7, 0x63, 0x8f} + out := make([]byte, len(check)) + rs := NewRSEncoder(f, len(check)) + for i := 0; i < b.N; i++ { + rs.ECC(data, out) + } + b.SetBytes(int64(len(data))) + if !bytes.Equal(out, check) { + fmt.Printf("have %#v want %#v\n", out, check) + } +} + +func TestGen(t *testing.T) { + for i := 0; i < 256; i++ { + _, lg := f.gen(i) + if lg[0] != 0 { + t.Errorf("#%d: %x", i, lg) + } + } +} + +func TestReducible(t *testing.T) { + var count = []int{1, 2, 3, 6, 9, 18, 30, 56, 99, 186} // oeis.org/A1037 + for i, want := range count { + n := 0 + for p := 1 << uint(i+2); p < 1< +*/ +import "C" + +import ( + "fmt" + "image" + "image/color" + "unsafe" +) + +type Version int + +type Mode int + +const ( + Numeric Mode = C.QR_MODE_NUM + Alphanumeric Mode = C.QR_MODE_AN + EightBit Mode = C.QR_MODE_8 +) + +type Level int + +const ( + L Level = C.QR_ECLEVEL_L + M Level = C.QR_ECLEVEL_M + Q Level = C.QR_ECLEVEL_Q + H Level = C.QR_ECLEVEL_H +) + +type Pixel int + +const ( + Black Pixel = 1 << iota + DataECC + Format + PVersion + Timing + Alignment + Finder + NonData +) + +type Code struct { + Version int + Width int + Pixel [][]Pixel + Scale int +} + +func (*Code) ColorModel() color.Model { + return color.RGBAModel +} + +func (c *Code) Bounds() image.Rectangle { + d := (c.Width + 8) * c.Scale + return image.Rect(0, 0, d, d) +} + +var ( + white color.Color = color.RGBA{0xFF, 0xFF, 0xFF, 0xFF} + black color.Color = color.RGBA{0x00, 0x00, 0x00, 0xFF} + blue color.Color = color.RGBA{0x00, 0x00, 0x80, 0xFF} + red color.Color = color.RGBA{0xFF, 0x40, 0x40, 0xFF} + yellow color.Color = color.RGBA{0xFF, 0xFF, 0x00, 0xFF} + gray color.Color = color.RGBA{0x80, 0x80, 0x80, 0xFF} + green color.Color = color.RGBA{0x22, 0x8B, 0x22, 0xFF} +) + +func (c *Code) At(x, y int) color.Color { + x = x/c.Scale - 4 + y = y/c.Scale - 4 + if 0 <= x && x < c.Width && 0 <= y && y < c.Width { + switch p := c.Pixel[y][x]; { + case p&Black == 0: + // nothing + case p&DataECC != 0: + return black + case p&Format != 0: + return blue + case p&PVersion != 0: + return red + case p&Timing != 0: + return yellow + case p&Alignment != 0: + return gray + case p&Finder != 0: + return green + } + } + return white +} + +type Chunk struct { + Mode Mode + Text string +} + +func Encode(version Version, level Level, mode Mode, text string) (*Code, error) { + return EncodeChunk(version, level, Chunk{mode, text}) +} + +func EncodeChunk(version Version, level Level, chunk ...Chunk) (*Code, error) { + qi, err := C.QRinput_new2(C.int(version), C.QRecLevel(level)) + if qi == nil { + return nil, fmt.Errorf("QRinput_new2: %v", err) + } + defer C.QRinput_free(qi) + for _, ch := range chunk { + data := []byte(ch.Text) + n, err := C.QRinput_append(qi, C.QRencodeMode(ch.Mode), C.int(len(data)), (*C.uchar)(&data[0])) + if n < 0 { + return nil, fmt.Errorf("QRinput_append %q: %v", data, err) + } + } + + qc, err := C.QRcode_encodeInput(qi) + if qc == nil { + return nil, fmt.Errorf("QRinput_encodeInput: %v", err) + } + + c := &Code{ + Version: int(qc.version), + Width: int(qc.width), + Scale: 16, + } + pix := make([]Pixel, c.Width*c.Width) + cdat := (*[1000 * 1000]byte)(unsafe.Pointer(qc.data))[:len(pix)] + for i := range pix { + pix[i] = Pixel(cdat[i]) + } + c.Pixel = make([][]Pixel, c.Width) + for i := range c.Pixel { + c.Pixel[i] = pix[i*c.Width : (i+1)*c.Width] + } + return c, nil +} diff --git a/png.go b/png.go new file mode 100644 index 0000000..db49d05 --- /dev/null +++ b/png.go @@ -0,0 +1,400 @@ +// Copyright 2011 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 qr + +// PNG writer for QR codes. + +import ( + "bytes" + "encoding/binary" + "hash" + "hash/crc32" +) + +// PNG returns a PNG image displaying the code. +// +// PNG uses a custom encoder tailored to QR codes. +// Its compressed size is about 2x away from optimal, +// but it runs about 20x faster than calling png.Encode +// on c.Image(). +func (c *Code) PNG() []byte { + var p pngWriter + return p.encode(c) +} + +type pngWriter struct { + tmp [16]byte + wctmp [4]byte + buf bytes.Buffer + zlib bitWriter + crc hash.Hash32 +} + +var pngHeader = []byte("\x89PNG\r\n\x1a\n") + +func (w *pngWriter) encode(c *Code) []byte { + scale := c.Scale + siz := c.Size + + w.buf.Reset() + + // Header + w.buf.Write(pngHeader) + + // Header block + binary.BigEndian.PutUint32(w.tmp[0:4], uint32((siz+8)*scale)) + binary.BigEndian.PutUint32(w.tmp[4:8], uint32((siz+8)*scale)) + w.tmp[8] = 1 // 1-bit + w.tmp[9] = 0 // gray + w.tmp[10] = 0 + w.tmp[11] = 0 + w.tmp[12] = 0 + w.writeChunk("IHDR", w.tmp[:13]) + + // Comment + w.writeChunk("tEXt", comment) + + // Data + w.zlib.writeCode(c) + w.writeChunk("IDAT", w.zlib.bytes.Bytes()) + + // End + w.writeChunk("IEND", nil) + + return w.buf.Bytes() +} + +var comment = []byte("Software\x00QR-PNG http://qr.swtch.com/") + +func (w *pngWriter) writeChunk(name string, data []byte) { + if w.crc == nil { + w.crc = crc32.NewIEEE() + } + binary.BigEndian.PutUint32(w.wctmp[0:4], uint32(len(data))) + w.buf.Write(w.wctmp[0:4]) + w.crc.Reset() + copy(w.wctmp[0:4], name) + w.buf.Write(w.wctmp[0:4]) + w.crc.Write(w.wctmp[0:4]) + w.buf.Write(data) + w.crc.Write(data) + crc := w.crc.Sum32() + binary.BigEndian.PutUint32(w.wctmp[0:4], crc) + w.buf.Write(w.wctmp[0:4]) +} + +func (b *bitWriter) writeCode(c *Code) { + const ftNone = 0 + + b.adler32.Reset() + b.bytes.Reset() + b.nbit = 0 + + scale := c.Scale + siz := c.Size + + // zlib header + b.tmp[0] = 0x78 + b.tmp[1] = 0 + b.tmp[1] += uint8(31 - (uint16(b.tmp[0])<<8+uint16(b.tmp[1]))%31) + b.bytes.Write(b.tmp[0:2]) + + // Start flate block. + b.writeBits(1, 1, false) // final block + b.writeBits(1, 2, false) // compressed, fixed Huffman tables + + // White border. + // First row. + b.byte(ftNone) + n := (scale*(siz+8) + 7) / 8 + b.byte(255) + b.repeat(n-1, 1) + // 4*scale rows total. + b.repeat((4*scale-1)*(1+n), 1+n) + + for i := 0; i < 4*scale; i++ { + b.adler32.WriteNByte(ftNone, 1) + b.adler32.WriteNByte(255, n) + } + + row := make([]byte, 1+n) + for y := 0; y < siz; y++ { + row[0] = ftNone + j := 1 + var z uint8 + nz := 0 + for x := -4; x < siz+4; x++ { + // Raw data. + for i := 0; i < scale; i++ { + z <<= 1 + if !c.Black(x, y) { + z |= 1 + } + if nz++; nz == 8 { + row[j] = z + j++ + nz = 0 + } + } + } + if j < len(row) { + row[j] = z + } + for _, z := range row { + b.byte(z) + } + + // Scale-1 copies. + b.repeat((scale-1)*(1+n), 1+n) + + b.adler32.WriteN(row, scale) + } + + // White border. + // First row. + b.byte(ftNone) + b.byte(255) + b.repeat(n-1, 1) + // 4*scale rows total. + b.repeat((4*scale-1)*(1+n), 1+n) + + for i := 0; i < 4*scale; i++ { + b.adler32.WriteNByte(ftNone, 1) + b.adler32.WriteNByte(255, n) + } + + // End of block. + b.hcode(256) + b.flushBits() + + // adler32 + binary.BigEndian.PutUint32(b.tmp[0:], b.adler32.Sum32()) + b.bytes.Write(b.tmp[0:4]) +} + +// A bitWriter is a write buffer for bit-oriented data like deflate. +type bitWriter struct { + bytes bytes.Buffer + bit uint32 + nbit uint + + tmp [4]byte + adler32 adigest +} + +func (b *bitWriter) writeBits(bit uint32, nbit uint, rev bool) { + // reverse, for huffman codes + if rev { + br := uint32(0) + for i := uint(0); i < nbit; i++ { + br |= ((bit >> i) & 1) << (nbit - 1 - i) + } + bit = br + } + b.bit |= bit << b.nbit + b.nbit += nbit + for b.nbit >= 8 { + b.bytes.WriteByte(byte(b.bit)) + b.bit >>= 8 + b.nbit -= 8 + } +} + +func (b *bitWriter) flushBits() { + if b.nbit > 0 { + b.bytes.WriteByte(byte(b.bit)) + b.nbit = 0 + b.bit = 0 + } +} + +func (b *bitWriter) hcode(v int) { + /* + Lit Value Bits Codes + --------- ---- ----- + 0 - 143 8 00110000 through + 10111111 + 144 - 255 9 110010000 through + 111111111 + 256 - 279 7 0000000 through + 0010111 + 280 - 287 8 11000000 through + 11000111 + */ + switch { + case v <= 143: + b.writeBits(uint32(v)+0x30, 8, true) + case v <= 255: + b.writeBits(uint32(v-144)+0x190, 9, true) + case v <= 279: + b.writeBits(uint32(v-256)+0, 7, true) + case v <= 287: + b.writeBits(uint32(v-280)+0xc0, 8, true) + default: + panic("invalid hcode") + } +} + +func (b *bitWriter) byte(x byte) { + b.hcode(int(x)) +} + +func (b *bitWriter) codex(c int, val int, nx uint) { + b.hcode(c + val>>nx) + b.writeBits(uint32(val)&(1<= 258+3; n -= 258 { + b.repeat1(258, d) + } + if n > 258 { + // 258 < n < 258+3 + b.repeat1(10, d) + b.repeat1(n-10, d) + return + } + if n < 3 { + panic("invalid flate repeat") + } + b.repeat1(n, d) +} + +func (b *bitWriter) repeat1(n, d int) { + /* + Extra Extra Extra + Code Bits Length(s) Code Bits Lengths Code Bits Length(s) + ---- ---- ------ ---- ---- ------- ---- ---- ------- + 257 0 3 267 1 15,16 277 4 67-82 + 258 0 4 268 1 17,18 278 4 83-98 + 259 0 5 269 2 19-22 279 4 99-114 + 260 0 6 270 2 23-26 280 4 115-130 + 261 0 7 271 2 27-30 281 5 131-162 + 262 0 8 272 2 31-34 282 5 163-194 + 263 0 9 273 3 35-42 283 5 195-226 + 264 0 10 274 3 43-50 284 5 227-257 + 265 1 11,12 275 3 51-58 285 0 258 + 266 1 13,14 276 3 59-66 + */ + switch { + case n <= 10: + b.codex(257, n-3, 0) + case n <= 18: + b.codex(265, n-11, 1) + case n <= 34: + b.codex(269, n-19, 2) + case n <= 66: + b.codex(273, n-35, 3) + case n <= 130: + b.codex(277, n-67, 4) + case n <= 257: + b.codex(281, n-131, 5) + case n == 258: + b.hcode(285) + default: + panic("invalid repeat length") + } + + /* + Extra Extra Extra + Code Bits Dist Code Bits Dist Code Bits Distance + ---- ---- ---- ---- ---- ------ ---- ---- -------- + 0 0 1 10 4 33-48 20 9 1025-1536 + 1 0 2 11 4 49-64 21 9 1537-2048 + 2 0 3 12 5 65-96 22 10 2049-3072 + 3 0 4 13 5 97-128 23 10 3073-4096 + 4 1 5,6 14 6 129-192 24 11 4097-6144 + 5 1 7,8 15 6 193-256 25 11 6145-8192 + 6 2 9-12 16 7 257-384 26 12 8193-12288 + 7 2 13-16 17 7 385-512 27 12 12289-16384 + 8 3 17-24 18 8 513-768 28 13 16385-24576 + 9 3 25-32 19 8 769-1024 29 13 24577-32768 + */ + if d <= 4 { + b.writeBits(uint32(d-1), 5, true) + } else if d <= 32768 { + nbit := uint(16) + for d <= 1<<(nbit-1) { + nbit-- + } + v := uint32(d - 1) + v &^= 1 << (nbit - 1) // top bit is implicit + code := uint32(2*nbit - 2) // second bit is low bit of code + code |= v >> (nbit - 2) + v &^= 1 << (nbit - 2) + b.writeBits(code, 5, true) + // rest of bits follow + b.writeBits(uint32(v), nbit-2, false) + } else { + panic("invalid repeat distance") + } +} + +func (b *bitWriter) run(v byte, n int) { + if n == 0 { + return + } + b.byte(v) + if n-1 < 3 { + for i := 0; i < n-1; i++ { + b.byte(v) + } + } else { + b.repeat(n-1, 1) + } +} + +type adigest struct { + a, b uint32 +} + +func (d *adigest) Reset() { d.a, d.b = 1, 0 } + +const amod = 65521 + +func aupdate(a, b uint32, pi byte, n int) (aa, bb uint32) { + // TODO(rsc): 6g doesn't do magic multiplies for b %= amod, + // only for b = b%amod. + + // invariant: a, b < amod + if pi == 0 { + b += uint32(n%amod) * a + b = b % amod + return a, b + } + + // n times: + // a += pi + // b += a + // is same as + // b += n*a + n*(n+1)/2*pi + // a += n*pi + m := uint32(n) + b += (m % amod) * a + b = b % amod + b += (m * (m + 1) / 2) % amod * uint32(pi) + b = b % amod + a += (m % amod) * uint32(pi) + a = a % amod + return a, b +} + +func afinish(a, b uint32) uint32 { + return b<<16 | a +} + +func (d *adigest) WriteN(p []byte, n int) { + for i := 0; i < n; i++ { + for _, pi := range p { + d.a, d.b = aupdate(d.a, d.b, pi, 1) + } + } +} + +func (d *adigest) WriteNByte(pi byte, n int) { + d.a, d.b = aupdate(d.a, d.b, pi, n) +} + +func (d *adigest) Sum32() uint32 { return afinish(d.a, d.b) } diff --git a/png_test.go b/png_test.go new file mode 100644 index 0000000..27a6229 --- /dev/null +++ b/png_test.go @@ -0,0 +1,73 @@ +// Copyright 2011 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 qr + +import ( + "bytes" + "image" + "image/color" + "image/png" + "io/ioutil" + "testing" +) + +func TestPNG(t *testing.T) { + c, err := Encode("hello, world", L) + if err != nil { + t.Fatal(err) + } + pngdat := c.PNG() + if true { + ioutil.WriteFile("x.png", pngdat, 0666) + } + m, err := png.Decode(bytes.NewBuffer(pngdat)) + if err != nil { + t.Fatal(err) + } + gm := m.(*image.Gray) + + scale := c.Scale + siz := c.Size + nbad := 0 + for y := 0; y < scale*(8+siz); y++ { + for x := 0; x < scale*(8+siz); x++ { + v := byte(255) + if c.Black(x/scale-4, y/scale-4) { + v = 0 + } + if gv := gm.At(x, y).(color.Gray).Y; gv != v { + t.Errorf("%d,%d = %d, want %d", x, y, gv, v) + if nbad++; nbad >= 20 { + t.Fatalf("too many bad pixels") + } + } + } + } +} + +func BenchmarkPNG(b *testing.B) { + c, err := Encode("0123456789012345678901234567890123456789", L) + if err != nil { + panic(err) + } + var bytes []byte + for i := 0; i < b.N; i++ { + bytes = c.PNG() + } + b.SetBytes(int64(len(bytes))) +} + +func BenchmarkImagePNG(b *testing.B) { + c, err := Encode("0123456789012345678901234567890123456789", L) + if err != nil { + panic(err) + } + var buf bytes.Buffer + for i := 0; i < b.N; i++ { + buf.Reset() + png.Encode(&buf, c.Image()) + } + b.SetBytes(int64(buf.Len())) +} diff --git a/qr.go b/qr.go new file mode 100644 index 0000000..254b532 --- /dev/null +++ b/qr.go @@ -0,0 +1,116 @@ +// Copyright 2011 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 qr encodes QR codes. +*/ +package qr + +import ( + "errors" + "image" + "image/color" + + "rsc.io/qr/coding" +) + +// A Level denotes a QR error correction level. +// From least to most tolerant of errors, they are L, M, Q, H. +type Level int + +const ( + L Level = iota // 20% redundant + M // 38% redundant + Q // 55% redundant + H // 65% redundant +) + +// Encode returns an encoding of text at the given error correction level. +func Encode(text string, level Level) (*Code, error) { + // Pick data encoding, smallest first. + // We could split the string and use different encodings + // but that seems like overkill for now. + var enc coding.Encoding + switch { + case coding.Num(text).Check() == nil: + enc = coding.Num(text) + case coding.Alpha(text).Check() == nil: + enc = coding.Alpha(text) + default: + enc = coding.String(text) + } + + // Pick size. + l := coding.Level(level) + var v coding.Version + for v = coding.MinVersion; ; v++ { + if v > coding.MaxVersion { + return nil, errors.New("text too long to encode as QR") + } + if enc.Bits(v) <= v.DataBytes(l)*8 { + break + } + } + + // Build and execute plan. + p, err := coding.NewPlan(v, l, 0) + if err != nil { + return nil, err + } + cc, err := p.Encode(enc) + if err != nil { + return nil, err + } + + // TODO: Pick appropriate mask. + + return &Code{cc.Bitmap, cc.Size, cc.Stride, 8}, nil +} + +// A Code is a square pixel grid. +// It implements image.Image and direct PNG encoding. +type Code struct { + Bitmap []byte // 1 is black, 0 is white + Size int // number of pixels on a side + Stride int // number of bytes per row + Scale int // number of image pixels per QR pixel +} + +// Black returns true if the pixel at (x,y) is black. +func (c *Code) Black(x, y int) bool { + return 0 <= x && x < c.Size && 0 <= y && y < c.Size && + c.Bitmap[y*c.Stride+x/8]&(1<