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QR-Code-generator/c/qrcodegen.c

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Began writing new port of this library in C by implementing Reed-Solomon functions.
2017-04-17 17:34:21 +00:00
/*
* QR Code generator library (C)
*
* Copyright (c) Project Nayuki
* https://www.nayuki.io/page/qr-code-generator-library
*
* (MIT License)
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
* - The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* - The Software is provided "as is", without warranty of any kind, express or
* implied, including but not limited to the warranties of merchantability,
* fitness for a particular purpose and noninfringement. In no event shall the
* authors or copyright holders be liable for any claim, damages or other
* liability, whether in an action of contract, tort or otherwise, arising from,
* out of or in connection with the Software or the use or other dealings in the
* Software.
*/
#include <assert.h>
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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#include <limits.h>
Continued implementing C library by adding functions to draw QR Code function patterns.
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#include <stdlib.h>
Began writing new port of this library in C by implementing Reed-Solomon functions.
2017-04-17 17:34:21 +00:00
#include <string.h>
Continued implementing C library by adding header file and text-testing functions.
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#include "qrcodegen.h"
Began writing new port of this library in C by implementing Reed-Solomon functions.
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/*---- Forward declarations for private functions ----*/
Continued implementing C library by adding and updating code to support automatic mask selection and penalty calculation.
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static long getPenaltyScore(const uint8_t qrcode[], int size);
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
2017-04-19 18:07:02 +00:00
static void appendBitsToBuffer(uint16_t val, int numBits, uint8_t buffer[], int *bitLen);
static int getNumDataCodewords(int version, enum qrcodegen_Ecc ecl);
Continued implementing C library by adding low-level QR Code get/set functions.
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static bool getModule(const uint8_t qrcode[], int size, int x, int y);
static void setModule(uint8_t qrcode[], int size, int x, int y, bool isBlack);
static void setModuleBounded(uint8_t qrcode[], int size, int x, int y, bool isBlack);
Continued implementing C library by adding functions to fill QR Code function patterns.
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static void initializeFunctionalModules(int version, uint8_t qrcode[]);
Continued implementing C library by adding functions to draw QR Code function patterns.
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static void drawWhiteFunctionModules(uint8_t qrcode[], int version);
static void drawFormatBits(enum qrcodegen_Ecc ecl, enum qrcodegen_Mask mask, uint8_t qrcode[], int size);
Continued implementing C library by adding functions to fill QR Code function patterns.
2017-04-17 18:26:29 +00:00
static int getAlignmentPatternPositions(int version, uint8_t result[7]);
Continued implementing C library by adding functions to append Reed-Solomon ECC and interleave blocks.
2017-04-19 16:42:21 +00:00
static void appendErrorCorrection(uint8_t data[], int version, enum qrcodegen_Ecc ecl, uint8_t result[]);
static int getNumRawDataModules(int version);
Refactored C code to use size instead of version in drawCodewords().
2017-04-19 20:59:02 +00:00
static void drawCodewords(const uint8_t data[], int dataLen, uint8_t qrcode[], int size);
Continued implementing C library by adding functions to draw codewords and apply masking.
2017-04-17 20:36:38 +00:00
static void applyMask(const uint8_t functionModules[], uint8_t qrcode[], int size, int mask);
Began writing new port of this library in C by implementing Reed-Solomon functions.
2017-04-17 17:34:21 +00:00
static void calcReedSolomonGenerator(int degree, uint8_t result[]);
static void calcReedSolomonRemainder(const uint8_t data[], int dataLen, const uint8_t generator[], int degree, uint8_t result[]);
static uint8_t finiteFieldMultiply(uint8_t x, uint8_t y);
Continued implementing C library by adding functions to append Reed-Solomon ECC and interleave blocks.
2017-04-19 16:42:21 +00:00
/*---- Private tables of constants ----*/
Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.
2017-04-19 20:45:50 +00:00
static const char *ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
Continued implementing C library by adding functions to append Reed-Solomon ECC and interleave blocks.
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static const int16_t NUM_ERROR_CORRECTION_CODEWORDS[4][41] = {
// Version: (note that index 0 is for padding, and is set to an illegal value)
//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 Error correction level
{-1, 7, 10, 15, 20, 26, 36, 40, 48, 60, 72, 80, 96, 104, 120, 132, 144, 168, 180, 196, 224, 224, 252, 270, 300, 312, 336, 360, 390, 420, 450, 480, 510, 540, 570, 570, 600, 630, 660, 720, 750}, // Low
{-1, 10, 16, 26, 36, 48, 64, 72, 88, 110, 130, 150, 176, 198, 216, 240, 280, 308, 338, 364, 416, 442, 476, 504, 560, 588, 644, 700, 728, 784, 812, 868, 924, 980, 1036, 1064, 1120, 1204, 1260, 1316, 1372}, // Medium
{-1, 13, 22, 36, 52, 72, 96, 108, 132, 160, 192, 224, 260, 288, 320, 360, 408, 448, 504, 546, 600, 644, 690, 750, 810, 870, 952, 1020, 1050, 1140, 1200, 1290, 1350, 1440, 1530, 1590, 1680, 1770, 1860, 1950, 2040}, // Quartile
{-1, 17, 28, 44, 64, 88, 112, 130, 156, 192, 224, 264, 308, 352, 384, 432, 480, 532, 588, 650, 700, 750, 816, 900, 960, 1050, 1110, 1200, 1260, 1350, 1440, 1530, 1620, 1710, 1800, 1890, 1980, 2100, 2220, 2310, 2430}, // High
};
const int8_t NUM_ERROR_CORRECTION_BLOCKS[4][41] = {
// Version: (note that index 0 is for padding, and is set to an illegal value)
//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 Error correction level
{-1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 4, 4, 4, 6, 6, 6, 6, 7, 8, 8, 9, 9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25}, // Low
{-1, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5, 5, 8, 9, 9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49}, // Medium
{-1, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8, 8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68}, // Quartile
{-1, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81}, // High
};
Continued implementing C library by adding and updating code to support automatic mask selection and penalty calculation.
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static const int PENALTY_N1 = 3;
static const int PENALTY_N2 = 3;
static const int PENALTY_N3 = 40;
static const int PENALTY_N4 = 10;
Continued implementing C library by adding functions to append Reed-Solomon ECC and interleave blocks.
2017-04-19 16:42:21 +00:00
Added and updated section comments in C code.
2017-04-19 21:08:05 +00:00
/*---- Top-level QR Code encoding functions ----*/
Began writing new port of this library in C by implementing Reed-Solomon functions.
2017-04-17 17:34:21 +00:00
Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.
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// Public function - see documentation comment in header file.
int qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[],
Continued implementing C library by adding logic to support boosting ECC level.
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enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl) {
Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.
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assert(1 <= minVersion && minVersion <= maxVersion && maxVersion <= 40);
assert(0 <= (int)ecl && (int)ecl <= 3 && -1 <= (int)mask && (int)mask <= 7);
// Get text properties
int textLen = 0;
bool isNumeric = true;
bool isAlphanumeric = true;
for (const char *p = text; *p != '\0'; p++, textLen++) {
if (textLen == INT16_MAX) // Note: INT16_MAX < INT_MAX && INT16_MAX < SIZE_MAX
return 0;
char c = *p;
if (c < '0' || c > '9') {
isNumeric = false;
isAlphanumeric &= strchr(ALPHANUMERIC_CHARSET, c) != NULL;
}
}
int textBits;
if (isNumeric) { // textBits = textLen * 3 + ceil(textLen / 3)
if (textLen > INT_MAX / 3)
return 0;
textBits = textLen * 3;
if (textLen > INT_MAX - 2 || textLen > INT_MAX - textBits)
return 0;
textBits += (textLen + 2) / 3;
} else if (isAlphanumeric) { // textBits = textLen * 5 + ceil(textLen / 2)
if (textLen > INT_MAX / 5)
return 0;
textBits = textLen * 5;
if (textLen > INT_MAX - 1 || textLen > INT_MAX - textBits)
return 0;
textBits += (textLen + 1) / 2;
} else { // Use binary mode
if (textLen > qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion))
return 0;
for (int i = 0; i < textLen; i++)
tempBuffer[i] = (uint8_t)text[i];
Continued implementing C library by adding logic to support boosting ECC level.
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return qrcodegen_encodeBinary(tempBuffer, (size_t)textLen, qrcode, ecl, minVersion, maxVersion, mask, boostEcl);
Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.
2017-04-19 20:45:50 +00:00
}
int version;
int dataUsedBits = -1;
int dataCapacityBits = -1;
int lengthBits = -1;
for (version = minVersion; ; version++) {
if (version <= 9)
lengthBits = isNumeric ? 10 : 9;
else if (version <= 26)
lengthBits = isNumeric ? 12 : 11;
else
lengthBits = isNumeric ? 14 : 13;
if (textLen < (1 << lengthBits)) {
dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available
dataUsedBits = 4 + lengthBits;
if (textBits > INT_MAX - dataUsedBits)
continue;
dataUsedBits += textBits;
if (dataUsedBits <= dataCapacityBits)
break; // This version number is found to be suitable
}
if (version >= maxVersion) // All versions in the range could not fit the given data
return 0;
}
assert(dataUsedBits >= 0 && dataCapacityBits >= 0);
Continued implementing C library by adding logic to support boosting ECC level.
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if (boostEcl) {
if (dataUsedBits <= getNumDataCodewords(version, qrcodegen_Ecc_MEDIUM ) * 8) ecl = qrcodegen_Ecc_MEDIUM ;
if (dataUsedBits <= getNumDataCodewords(version, qrcodegen_Ecc_QUARTILE) * 8) ecl = qrcodegen_Ecc_QUARTILE;
if (dataUsedBits <= getNumDataCodewords(version, qrcodegen_Ecc_HIGH ) * 8) ecl = qrcodegen_Ecc_HIGH ;
dataCapacityBits = getNumDataCodewords(version, ecl) * 8;
}
Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.
2017-04-19 20:45:50 +00:00
memset(qrcode, 0, qrcodegen_BUFFER_LEN_FOR_VERSION(version) * sizeof(qrcode[0]));
int bitLen = 0;
appendBitsToBuffer(isNumeric ? 1 : 2, 4, qrcode, &bitLen);
appendBitsToBuffer((uint16_t)textLen, lengthBits, qrcode, &bitLen);
if (isNumeric) {
int accumData = 0;
int accumCount = 0;
for (const char *p = text; *p != '\0'; p++) {
accumData = accumData * 10 + (*p - '0');
accumCount++;
if (accumCount == 3) {
appendBitsToBuffer(accumData, 10, qrcode, &bitLen);
accumData = 0;
accumCount = 0;
}
}
if (accumCount > 0) // 1 or 2 digits remaining
appendBitsToBuffer(accumData, accumCount * 3 + 1, qrcode, &bitLen);
} else { // isAlphanumeric
int accumData = 0;
int accumCount = 0;
for (const char *p = text; *p != '\0'; p++) {
accumData = accumData * 45 + (strchr(ALPHANUMERIC_CHARSET, *p) - ALPHANUMERIC_CHARSET);
accumCount++;
if (accumCount == 2) {
appendBitsToBuffer(accumData, 11, qrcode, &bitLen);
accumData = 0;
accumCount = 0;
}
}
if (accumCount > 0) // 1 character remaining
appendBitsToBuffer(accumData, 6, qrcode, &bitLen);
}
int terminatorBits = dataCapacityBits - bitLen;
if (terminatorBits > 4)
terminatorBits = 4;
appendBitsToBuffer(0, terminatorBits, qrcode, &bitLen);
appendBitsToBuffer(0, (8 - bitLen % 8) % 8, qrcode, &bitLen);
for (uint8_t padByte = 0xEC; bitLen < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
appendBitsToBuffer(padByte, 8, qrcode, &bitLen);
assert(bitLen % 8 == 0);
appendErrorCorrection(qrcode, version, ecl, tempBuffer);
initializeFunctionalModules(version, qrcode);
Refactored C code to use size instead of version in drawCodewords().
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drawCodewords(tempBuffer, getNumRawDataModules(version) / 8, qrcode, qrcodegen_getSize(version));
Continued implementing C library by adding main QR Code encoding function for text, including support for alphanumeric and numeric mode segments.
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drawWhiteFunctionModules(qrcode, version);
initializeFunctionalModules(version, tempBuffer);
if (mask == qrcodegen_Mask_AUTO) { // Automatically choose best mask
long minPenalty = LONG_MAX;
for (int i = 0; i < 8; i++) {
drawFormatBits(ecl, i, qrcode, qrcodegen_getSize(version));
applyMask(tempBuffer, qrcode, qrcodegen_getSize(version), i);
long penalty = getPenaltyScore(qrcode, qrcodegen_getSize(version));
if (penalty < minPenalty) {
mask = (enum qrcodegen_Mask)i;
minPenalty = penalty;
}
applyMask(tempBuffer, qrcode, qrcodegen_getSize(version), i); // Undoes the mask due to XOR
}
}
assert(0 <= (int)mask && (int)mask <= 7);
applyMask(tempBuffer, qrcode, qrcodegen_getSize(version), (int)mask);
drawFormatBits(ecl, (int)mask, qrcode, qrcodegen_getSize(version));
return version;
}
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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// Public function - see documentation comment in header file.
int qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcode[],
Continued implementing C library by adding logic to support boosting ECC level.
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enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl) {
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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assert(1 <= minVersion && minVersion <= maxVersion && maxVersion <= 40);
assert(0 <= (int)ecl && (int)ecl <= 3 && -1 <= (int)mask && (int)mask <= 7);
int version;
int dataUsedBits = -1;
int dataCapacityBits = -1;
for (version = minVersion; ; version++) {
if ((version <= 9 && dataLen < (1U << 8)) || dataLen < (1U << 16)) {
dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available
dataUsedBits = 4 + (version <= 9 ? 8 : 16);
if (dataLen > (unsigned int)INT_MAX / 8 || (unsigned int)(INT_MAX - dataUsedBits) < dataLen * 8)
continue;
dataUsedBits += dataLen * 8;
if (dataUsedBits <= dataCapacityBits)
break; // This version number is found to be suitable
}
if (version >= maxVersion) // All versions in the range could not fit the given data
return 0;
}
assert(dataUsedBits >= 0 && dataCapacityBits >= 0);
Continued implementing C library by adding logic to support boosting ECC level.
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if (boostEcl) {
if (dataUsedBits <= getNumDataCodewords(version, qrcodegen_Ecc_MEDIUM ) * 8) ecl = qrcodegen_Ecc_MEDIUM ;
if (dataUsedBits <= getNumDataCodewords(version, qrcodegen_Ecc_QUARTILE) * 8) ecl = qrcodegen_Ecc_QUARTILE;
if (dataUsedBits <= getNumDataCodewords(version, qrcodegen_Ecc_HIGH ) * 8) ecl = qrcodegen_Ecc_HIGH ;
dataCapacityBits = getNumDataCodewords(version, ecl) * 8;
}
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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memset(qrcode, 0, qrcodegen_BUFFER_LEN_FOR_VERSION(version) * sizeof(qrcode[0]));
int bitLen = 0;
appendBitsToBuffer(4, 4, qrcode, &bitLen);
appendBitsToBuffer((uint16_t)dataLen, (version <= 9 ? 8 : 16), qrcode, &bitLen);
for (size_t i = 0; i < dataLen; i++)
appendBitsToBuffer(dataAndTemp[i], 8, qrcode, &bitLen);
int terminatorBits = dataCapacityBits - bitLen;
if (terminatorBits > 4)
terminatorBits = 4;
appendBitsToBuffer(0, terminatorBits, qrcode, &bitLen);
appendBitsToBuffer(0, (8 - bitLen % 8) % 8, qrcode, &bitLen);
for (uint8_t padByte = 0xEC; bitLen < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
appendBitsToBuffer(padByte, 8, qrcode, &bitLen);
assert(bitLen % 8 == 0);
appendErrorCorrection(qrcode, version, ecl, dataAndTemp);
initializeFunctionalModules(version, qrcode);
Refactored C code to use size instead of version in drawCodewords().
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drawCodewords(dataAndTemp, getNumRawDataModules(version) / 8, qrcode, qrcodegen_getSize(version));
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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drawWhiteFunctionModules(qrcode, version);
initializeFunctionalModules(version, dataAndTemp);
Continued implementing C library by adding and updating code to support automatic mask selection and penalty calculation.
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if (mask == qrcodegen_Mask_AUTO) { // Automatically choose best mask
long minPenalty = LONG_MAX;
for (int i = 0; i < 8; i++) {
drawFormatBits(ecl, i, qrcode, qrcodegen_getSize(version));
applyMask(dataAndTemp, qrcode, qrcodegen_getSize(version), i);
long penalty = getPenaltyScore(qrcode, qrcodegen_getSize(version));
if (penalty < minPenalty) {
mask = (enum qrcodegen_Mask)i;
minPenalty = penalty;
}
applyMask(dataAndTemp, qrcode, qrcodegen_getSize(version), i); // Undoes the mask due to XOR
}
}
assert(0 <= (int)mask && (int)mask <= 7);
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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applyMask(dataAndTemp, qrcode, qrcodegen_getSize(version), (int)mask);
drawFormatBits(ecl, (int)mask, qrcode, qrcodegen_getSize(version));
return version;
}
Continued implementing C library by adding and updating code to support automatic mask selection and penalty calculation.
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// Calculates and returns the penalty score based on state of the given QR Code's current modules.
// This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score.
static long getPenaltyScore(const uint8_t qrcode[], int size) {
long result = 0;
// Adjacent modules in row having same color
for (int y = 0; y < size; y++) {
bool colorX = getModule(qrcode, size, 0, y);
for (int x = 1, runX = 1; x < size; x++) {
if (getModule(qrcode, size, x, y) != colorX) {
colorX = getModule(qrcode, size, x, y);
runX = 1;
} else {
runX++;
if (runX == 5)
result += PENALTY_N1;
else if (runX > 5)
result++;
}
}
}
// Adjacent modules in column having same color
for (int x = 0; x < size; x++) {
bool colorY = getModule(qrcode, size, x, 0);
for (int y = 1, runY = 1; y < size; y++) {
if (getModule(qrcode, size, x, y) != colorY) {
colorY = getModule(qrcode, size, x, y);
runY = 1;
} else {
runY++;
if (runY == 5)
result += PENALTY_N1;
else if (runY > 5)
result++;
}
}
}
// 2*2 blocks of modules having same color
for (int y = 0; y < size - 1; y++) {
for (int x = 0; x < size - 1; x++) {
bool color = getModule(qrcode, size, x, y);
if ( color == getModule(qrcode, size, x + 1, y) &&
color == getModule(qrcode, size, x, y + 1) &&
color == getModule(qrcode, size, x + 1, y + 1))
result += PENALTY_N2;
}
}
// Finder-like pattern in rows
for (int y = 0; y < size; y++) {
for (int x = 0, bits = 0; x < size; x++) {
bits = ((bits << 1) & 0x7FF) | (getModule(qrcode, size, x, y) ? 1 : 0);
if (x >= 10 && (bits == 0x05D || bits == 0x5D0)) // Needs 11 bits accumulated
result += PENALTY_N3;
}
}
// Finder-like pattern in columns
for (int x = 0; x < size; x++) {
for (int y = 0, bits = 0; y < size; y++) {
bits = ((bits << 1) & 0x7FF) | (getModule(qrcode, size, x, y) ? 1 : 0);
if (y >= 10 && (bits == 0x05D || bits == 0x5D0)) // Needs 11 bits accumulated
result += PENALTY_N3;
}
}
// Balance of black and white modules
int black = 0;
for (int y = 0; y < size; y++) {
for (int x = 0; x < size; x++) {
if (getModule(qrcode, size, x, y))
black++;
}
}
int total = size * size;
// Find smallest k such that (45-5k)% <= dark/total <= (55+5k)%
for (int k = 0; black*20 < (9-k)*total || black*20 > (11+k)*total; k++)
result += PENALTY_N4;
return result;
}
Continued implementing C library by adding a main QR Code encoding function and auxiliary functions.
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// Appends the given sequence of bits to the given byte-based bit buffer, increasing the bit length.
static void appendBitsToBuffer(uint16_t val, int numBits, uint8_t buffer[], int *bitLen) {
assert(0 <= numBits && numBits <= 16 && (long)val >> numBits == 0);
for (int i = numBits - 1; i >= 0; i--, (*bitLen)++)
buffer[*bitLen >> 3] |= ((val >> i) & 1) << (7 - (*bitLen & 7));
}
// Returns the number of 8-bit codewords that can be used for storing data (not ECC),
// for the given version number and error correction level. The result is in the range [9, 2956].
static int getNumDataCodewords(int version, enum qrcodegen_Ecc ecl) {
assert(0 <= (int)ecl && (int)ecl < 4 && 1 <= version && version <= 40);
return getNumRawDataModules(version) / 8 - NUM_ERROR_CORRECTION_CODEWORDS[(int)ecl][version];
}
Added and updated section comments in C code.
2017-04-19 21:08:05 +00:00
/*---- Basic QR Code information functions ----*/
Continued implementing C library by adding low-level QR Code get/set functions.
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// Public function - see documentation comment in header file.
int qrcodegen_getSize(int version) {
assert(1 <= version && version <= 40);
return version * 4 + 17;
}
// Public function - see documentation comment in header file.
bool qrcodegen_getModule(const uint8_t qrcode[], int version, int x, int y) {
int size = qrcodegen_getSize(version);
return (0 <= x && x < size && 0 <= y && y < size) && getModule(qrcode, size, x, y);
}
// Gets the module at the given coordinates, which must be in bounds.
static bool getModule(const uint8_t qrcode[], int size, int x, int y) {
assert(21 <= size && size <= 177 && 0 <= x && x < size && 0 <= y && y < size);
int index = y * size + x;
int bitIndex = index & 7;
int byteIndex = index >> 3;
return ((qrcode[byteIndex] >> bitIndex) & 1) != 0;
}
// Sets the module at the given coordinates, which must be in bounds.
static void setModule(uint8_t qrcode[], int size, int x, int y, bool isBlack) {
assert(21 <= size && size <= 177 && 0 <= x && x < size && 0 <= y && y < size);
int index = y * size + x;
int bitIndex = index & 7;
int byteIndex = index >> 3;
if (isBlack)
qrcode[byteIndex] |= 1 << bitIndex;
else
qrcode[byteIndex] &= (1 << bitIndex) ^ 0xFF;
}
// Sets the module at the given coordinates, doing nothing if out of bounds.
static void setModuleBounded(uint8_t qrcode[], int size, int x, int y, bool isBlack) {
if (0 <= x && x < size && 0 <= y && y < size)
setModule(qrcode, size, x, y, isBlack);
}
Added and updated section comments in C code.
2017-04-19 21:08:05 +00:00
/*---- QR Code drawing functions ----*/
Continued implementing C library by adding functions to fill QR Code function patterns.
2017-04-17 18:26:29 +00:00
// Fills the given QR Code grid with white modules for the given version's size,
// then marks every function module in the QR Code as black.
static void initializeFunctionalModules(int version, uint8_t qrcode[]) {
// Initialize QR Code
int size = qrcodegen_getSize(version);
memset(qrcode, 0, (size * size + 7) / 8 * sizeof(qrcode[0]));
// Fill horizontal and vertical timing patterns
for (int i = 0; i < size; i++) {
setModule(qrcode, size, 6, i, true);
setModule(qrcode, size, i, 6, true);
}
// Fill 3 finder patterns (all corners except bottom right)
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
setModule(qrcode, size, j, i, true);
setModule(qrcode, size, size - 1 - j, i, true);
setModule(qrcode, size, j, size - 1 - i, true);
}
}
// Fill numerous alignment patterns
Fixed and tweaked some pieces of C library code.
2017-04-17 19:15:40 +00:00
uint8_t alignPatPos[7] = {0};
Continued implementing C library by adding functions to fill QR Code function patterns.
2017-04-17 18:26:29 +00:00
int numAlign = getAlignmentPatternPositions(version, alignPatPos);
for (int i = 0; i < numAlign; i++) {
for (int j = 0; j < numAlign; j++) {
if ((i == 0 && j == 0) || (i == 0 && j == numAlign - 1) || (i == numAlign - 1 && j == 0))
continue; // Skip the three finder corners
else {
for (int k = -2; k <= 2; k++) {
for (int l = -2; l <= 2; l++)
setModule(qrcode, size, alignPatPos[i] + l, alignPatPos[j] + k, true);
}
}
}
}
// Fill format bits
for (int i = 0; i < 8; i++) {
setModule(qrcode, size, i, 8, true);
setModule(qrcode, size, 8, i, true);
setModule(qrcode, size, size - 1 - i, 8, true);
setModule(qrcode, size, 8, size - 1 - i, true);
}
setModule(qrcode, size, 8, 8, true);
// Fill version
if (version >= 7) {
Fixed C code logic for drawing 3*6 blocks of version information, tweaked another piece of similar logic for consistency without changing behavior.
2017-04-19 17:56:36 +00:00
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 3; j++) {
int k = size - 11 + j;
setModule(qrcode, size, k, i, true);
setModule(qrcode, size, i, k, true);
Continued implementing C library by adding functions to fill QR Code function patterns.
2017-04-17 18:26:29 +00:00
}
}
}
}
Continued implementing C library by adding functions to draw QR Code function patterns.
2017-04-17 20:02:51 +00:00
// Draws white function modules and possibly some black modules onto the given QR Code, without changing
// non-function modules. This does not draw the format bits. This requires all function modules to be previously
// marked black (namely by initializeFunctionalModules()), because this may skip redrawing black function modules.
static void drawWhiteFunctionModules(uint8_t qrcode[], int version) {
// Draw horizontal and vertical timing patterns
int size = qrcodegen_getSize(version);
for (int i = 7; i < size - 7; i += 2) {
setModule(qrcode, size, 6, i, false);
setModule(qrcode, size, i, 6, false);
}
// Draw 3 finder patterns
for (int i = -4; i <= 4; i++) {
for (int j = -4; j <= 4; j++) {
int dist = abs(i);
if (abs(j) > dist)
dist = abs(j);
if (dist == 2 || dist == 4) {
setModuleBounded(qrcode, size, 3 + j, 3 + i, false);
setModuleBounded(qrcode, size, size - 4 + j, 3 + i, false);
setModuleBounded(qrcode, size, 3 + j, size - 4 + i, false);
}
}
}
// Draw numerous alignment patterns
uint8_t alignPatPos[7] = {0};
int numAlign = getAlignmentPatternPositions(version, alignPatPos);
for (int i = 0; i < numAlign; i++) {
for (int j = 0; j < numAlign; j++) {
if ((i == 0 && j == 0) || (i == 0 && j == numAlign - 1) || (i == numAlign - 1 && j == 0))
continue; // Skip the three finder corners
else {
for (int k = -1; k <= 1; k++) {
for (int l = -1; l <= 1; l++)
setModule(qrcode, size, alignPatPos[i] + l, alignPatPos[j] + k, k == 0 && l == 0);
}
}
}
}
// Draw version block
if (version >= 7) {
// Calculate error correction code and pack bits
int rem = version; // version is uint6, in the range [7, 40]
for (int i = 0; i < 12; i++)
rem = (rem << 1) ^ ((rem >> 11) * 0x1F25);
long data = (long)version << 12 | rem; // uint18
assert(data >> 18 == 0);
// Draw two copies
Fixed C code logic for drawing 3*6 blocks of version information, tweaked another piece of similar logic for consistency without changing behavior.
2017-04-19 17:56:36 +00:00
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 3; j++) {
int k = size - 11 + j;
setModule(qrcode, size, k, i, (data & 1) != 0);
setModule(qrcode, size, i, k, (data & 1) != 0);
Continued implementing C library by adding functions to draw QR Code function patterns.
2017-04-17 20:02:51 +00:00
data >>= 1;
}
}
}
}
// Based on the given ECC level and mask, this calculates the format bits
// and draws their black and white modules onto the given QR Code.
static void drawFormatBits(enum qrcodegen_Ecc ecl, enum qrcodegen_Mask mask, uint8_t qrcode[], int size) {
// Calculate error correction code and pack bits
assert(0 <= (int)mask && (int)mask <= 7);
int data;
switch (ecl) {
case qrcodegen_Ecc_LOW : data = 1; break;
case qrcodegen_Ecc_MEDIUM : data = 0; break;
case qrcodegen_Ecc_QUARTILE: data = 3; break;
case qrcodegen_Ecc_HIGH : data = 2; break;
default: assert(false);
}
data = data << 3 | (int)mask; // ecl-derived value is uint2, mask is uint3
int rem = data;
for (int i = 0; i < 10; i++)
rem = (rem << 1) ^ ((rem >> 9) * 0x537);
data = data << 10 | rem;
data ^= 0x5412; // uint15
assert(data >> 15 == 0);
// Draw first copy
for (int i = 0; i <= 5; i++)
setModule(qrcode, size, 8, i, ((data >> i) & 1) != 0);
setModule(qrcode, size, 8, 7, ((data >> 6) & 1) != 0);
setModule(qrcode, size, 8, 8, ((data >> 7) & 1) != 0);
setModule(qrcode, size, 7, 8, ((data >> 8) & 1) != 0);
for (int i = 9; i < 15; i++)
setModule(qrcode, size, 14 - i, 8, ((data >> i) & 1) != 0);
// Draw second copy
for (int i = 0; i <= 7; i++)
setModule(qrcode, size, size - 1 - i, 8, ((data >> i) & 1) != 0);
for (int i = 8; i < 15; i++)
setModule(qrcode, size, 8, size - 15 + i, ((data >> i) & 1) != 0);
setModule(qrcode, size, 8, size - 8, true);
}
Continued implementing C library by adding functions to fill QR Code function patterns.
2017-04-17 18:26:29 +00:00
// Calculates the positions of alignment patterns in ascending order for the given version number,
// storing them to the given array and returning an array length in the range [0, 7].
static int getAlignmentPatternPositions(int version, uint8_t result[7]) {
if (version == 1)
return 0;
int size = qrcodegen_getSize(version);
int numAlign = version / 7 + 2;
int step;
if (version != 32)
step = (version * 4 + numAlign * 2 + 1) / (2 * numAlign - 2) * 2; // ceil((size - 13) / (2*numAlign - 2)) * 2
else // C-C-C-Combo breaker!
step = 26;
for (int i = numAlign - 1, pos = size - 7; i >= 1; i--, pos -= step)
result[i] = pos;
result[0] = 6;
return numAlign;
}
Continued implementing C library by adding functions to append Reed-Solomon ECC and interleave blocks.
2017-04-19 16:42:21 +00:00
// Appends error correction bytes to each block of the given data array, then interleaves bytes
// from the blocks and stores them in the result array. data[0 : rawCodewords - totalEcc] contains
// the input data. data[rawCodewords - totalEcc : rawCodewords] is used as a temporary work area
// and will be clobbered by this function. The final answer is stored in result[0 : rawCodewords].
static void appendErrorCorrection(uint8_t data[], int version, enum qrcodegen_Ecc ecl, uint8_t result[]) {
// Calculate parameter numbers
assert(0 <= (int)ecl && (int)ecl < 4 && 1 <= version && version <= 40);
int numBlocks = NUM_ERROR_CORRECTION_BLOCKS[(int)ecl][version];
int totalEcc = NUM_ERROR_CORRECTION_CODEWORDS[(int)ecl][version];
assert(totalEcc % numBlocks == 0);
int blockEccLen = totalEcc / numBlocks;
int rawCodewords = getNumRawDataModules(version) / 8;
int dataLen = rawCodewords - totalEcc;
int numShortBlocks = numBlocks - rawCodewords % numBlocks;
int shortBlockDataLen = rawCodewords / numBlocks - blockEccLen;
// Split data into blocks and append ECC after all data
uint8_t generator[30];
calcReedSolomonGenerator(blockEccLen, generator);
for (int i = 0, j = dataLen, k = 0; i < numBlocks; i++) {
int blockLen = shortBlockDataLen;
if (i >= numShortBlocks)
blockLen++;
calcReedSolomonRemainder(&data[k], blockLen, generator, blockEccLen, &data[j]);
j += blockEccLen;
k += blockLen;
}
// Interleave (not concatenate) the bytes from every block into a single sequence
for (int i = 0, k = 0; i < numBlocks; i++) {
for (int j = 0, l = i; j < shortBlockDataLen; j++, k++, l += numBlocks)
result[l] = data[k];
if (i >= numShortBlocks)
k++;
}
for (int i = numShortBlocks, l = numBlocks * shortBlockDataLen, k = (numShortBlocks + 1) * shortBlockDataLen;
i < numBlocks; i++, k += shortBlockDataLen + 1, l++)
result[l] = data[k];
for (int i = 0, k = dataLen; i < numBlocks; i++) {
for (int j = 0, l = dataLen + i; j < blockEccLen; j++, k++, l += numBlocks)
result[l] = data[k];
}
}
// Returns the number of data bits that can be stored in a QR Code of the given version number, after
// all function modules are excluded. This includes remainder bits, so it may not be a multiple of 8.
static int getNumRawDataModules(int version) {
assert(1 <= version && version <= 40);
int result = (16 * version + 128) * version + 64;
if (version >= 2) {
int numAlign = version / 7 + 2;
result -= (25 * numAlign - 10) * numAlign - 55;
if (version >= 7)
result -= 18 * 2; // Subtract version information
}
return result;
}
Continued implementing C library by adding functions to draw codewords and apply masking.
2017-04-17 20:36:38 +00:00
// Draws the raw codewords (including data and ECC) onto the given QR Code. This requires the initial state of
// the QR Code to be black at function modules and white at codeword modules (including unused remainder bits).
Refactored C code to use size instead of version in drawCodewords().
2017-04-19 20:59:02 +00:00
static void drawCodewords(const uint8_t data[], int dataLen, uint8_t qrcode[], int size) {
Continued implementing C library by adding functions to draw codewords and apply masking.
2017-04-17 20:36:38 +00:00
int i = 0; // Bit index into the data
// Do the funny zigzag scan
for (int right = size - 1; right >= 1; right -= 2) { // Index of right column in each column pair
if (right == 6)
right = 5;
for (int vert = 0; vert < size; vert++) { // Vertical counter
for (int j = 0; j < 2; j++) {
int x = right - j; // Actual x coordinate
bool upwards = ((right & 2) == 0) ^ (x < 6);
int y = upwards ? size - 1 - vert : vert; // Actual y coordinate
if (!getModule(qrcode, size, x, y) && i < dataLen * 8) {
bool black = ((data[i >> 3] >> (7 - (i & 7))) & 1) != 0;
setModule(qrcode, size, x, y, black);
i++;
}
// If there are any remainder bits (0 to 7), they are already
// set to 0/false/white when the grid of modules was initialized
}
}
}
assert(i == dataLen * 8);
}
Added and updated section comments in C code.
2017-04-19 21:08:05 +00:00
/*---- Reed-Solomon ECC generator functions ----*/
Continued implementing C library by adding functions to draw codewords and apply masking.
2017-04-17 20:36:38 +00:00
// XORs the data modules in this QR Code with the given mask pattern. Due to XOR's mathematical
// properties, calling applyMask(m) twice with the same value is equivalent to no change at all.
// This means it is possible to apply a mask, undo it, and try another mask. Note that a final
// well-formed QR Code symbol needs exactly one mask applied (not zero, not two, etc.).
static void applyMask(const uint8_t functionModules[], uint8_t qrcode[], int size, int mask) {
assert(0 <= mask && mask <= 7);
for (int y = 0; y < size; y++) {
for (int x = 0; x < size; x++) {
if (getModule(functionModules, size, x, y))
continue;
bool invert;
switch (mask) {
case 0: invert = (x + y) % 2 == 0; break;
case 1: invert = y % 2 == 0; break;
case 2: invert = x % 3 == 0; break;
case 3: invert = (x + y) % 3 == 0; break;
case 4: invert = (x / 3 + y / 2) % 2 == 0; break;
case 5: invert = x * y % 2 + x * y % 3 == 0; break;
case 6: invert = (x * y % 2 + x * y % 3) % 2 == 0; break;
case 7: invert = ((x + y) % 2 + x * y % 3) % 2 == 0; break;
default: assert(false);
}
bool val = getModule(qrcode, size, x, y);
setModule(qrcode, size, x, y, val ^ invert);
}
}
}
Began writing new port of this library in C by implementing Reed-Solomon functions.
2017-04-17 17:34:21 +00:00
// Calculates the Reed-Solomon generator polynomial of the given degree, storing in result[0 : degree].
static void calcReedSolomonGenerator(int degree, uint8_t result[]) {
// Start with the monomial x^0
assert(1 <= degree && degree <= 30);
memset(result, 0, degree * sizeof(result[0]));
result[degree - 1] = 1;
// Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
// drop the highest term, and store the rest of the coefficients in order of descending powers.
// Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
int root = 1;
for (int i = 0; i < degree; i++) {
// Multiply the current product by (x - r^i)
for (int j = 0; j < degree; j++) {
result[j] = finiteFieldMultiply(result[j], (uint8_t)root);
if (j + 1 < degree)
result[j] ^= result[j + 1];
}
root = (root << 1) ^ ((root >> 7) * 0x11D); // Multiply by 0x02 mod GF(2^8/0x11D)
}
}
// Calculates the remainder of the polynomial data[0 : dataLen] when divided by the generator[0 : degree], where all
// polynomials are in big endian and the generator has an implicit leading 1 term, storing the result in result[0 : degree].
static void calcReedSolomonRemainder(const uint8_t data[], int dataLen, const uint8_t generator[], int degree, uint8_t result[]) {
// Perform polynomial division
assert(1 <= degree && degree <= 30);
memset(result, 0, degree * sizeof(result[0]));
for (int i = 0; i < dataLen; i++) {
uint8_t factor = data[i] ^ result[0];
memmove(&result[0], &result[1], (degree - 1) * sizeof(result[0]));
result[degree - 1] = 0;
for (int j = 0; j < degree; j++)
result[j] ^= finiteFieldMultiply(generator[j], factor);
}
}
// Returns the product of the two given field elements modulo GF(2^8/0x11D). All argument values are valid.
static uint8_t finiteFieldMultiply(uint8_t x, uint8_t y) {
// Russian peasant multiplication
uint8_t z = 0;
for (int i = 7; i >= 0; i--) {
z = (z << 1) ^ ((z >> 7) * 0x11D);
z ^= ((y >> i) & 1) * x;
}
return z;
}