/* * QR Code generator library (C) * * Copyright (c) Project Nayuki. (MIT License) * https://www.nayuki.io/page/qr-code-generator-library * * 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> #include <limits.h> #include <stdlib.h> #include <string.h> #include "qrcodegen.h"5 includes #ifndef QRCODEGEN_TEST #define testable static // Keep functions private #else #define testable // Expose private functions #endif /*---- Forward declarations for private functions ----*/ // Regarding all public and private functions defined in this source file: // - They require all pointer/array arguments to be not null unless the array length is zero. // - They only read input scalar/array arguments, write to output pointer/array // arguments, and return scalar values; they are "pure" functions. // - They don't read mutable global variables or write to any global variables. // - They don't perform I/O, read the clock, print to console, etc. // - They allocate a small and constant amount of stack memory. // - They don't allocate or free any memory on the heap. // - They don't recurse or mutually recurse. All the code // could be inlined into the top-level public functions. // - They run in at most quadratic time with respect to input arguments. // Most functions run in linear time, and some in constant time. // There are no unbounded loops or non-obvious termination conditions. // - They are completely thread-safe if the caller does not give the // same writable buffer to concurrent calls to these functions. testable void appendBitsToBuffer(unsigned int val, int numBits, uint8_t buffer[], int *bitLen); testable void addEccAndInterleave(uint8_t data[], int version, enum qrcodegen_Ecc ecl, uint8_t result[]); testable int getNumDataCodewords(int version, enum qrcodegen_Ecc ecl); testable int getNumRawDataModules(int ver); testable void reedSolomonComputeDivisor(int degree, uint8_t result[]); testable void reedSolomonComputeRemainder(const uint8_t data[], int dataLen, const uint8_t generator[], int degree, uint8_t result[]); testable uint8_t reedSolomonMultiply(uint8_t x, uint8_t y); testable void initializeFunctionModules(int version, uint8_t qrcode[]); static void drawWhiteFunctionModules(uint8_t qrcode[], int version); static void drawFormatBits(enum qrcodegen_Ecc ecl, enum qrcodegen_Mask mask, uint8_t qrcode[]); testable int getAlignmentPatternPositions(int version, uint8_t result[7]); static void fillRectangle(int left, int top, int width, int height, uint8_t qrcode[]); static void drawCodewords(const uint8_t data[], int dataLen, uint8_t qrcode[]); static void applyMask(const uint8_t functionModules[], uint8_t qrcode[], enum qrcodegen_Mask mask); static long getPenaltyScore(const uint8_t qrcode[]); static int finderPenaltyCountPatterns(const int runHistory[7], int qrsize); static int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, int runHistory[7], int qrsize); static void finderPenaltyAddHistory(int currentRunLength, int runHistory[7]); testable bool getModule(const uint8_t qrcode[], int x, int y); testable void setModule(uint8_t qrcode[], int x, int y, bool isBlack); testable void setModuleBounded(uint8_t qrcode[], int x, int y, bool isBlack); static bool getBit(int x, int i); testable int calcSegmentBitLength(enum qrcodegen_Mode mode, size_t numChars); testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int version); static int numCharCountBits(enum qrcodegen_Mode mode, int version); /*---- Private tables of constants ----*/ // The set of all legal characters in alphanumeric mode, where each character // value maps to the index in the string. For checking text and encoding segments. static const char *ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"; // For generating error correction codes. testable const int8_t ECC_CODEWORDS_PER_BLOCK[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, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30}, // Low {-1, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28}, // Medium {-1, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30}, // Quartile {-1, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30}, // High }{...}; #define qrcodegen_REED_SOLOMON_DEGREE_MAX 30 // Based on the table above // For generating error correction codes. testable 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 }{...}; // For automatic mask pattern selection. static const int PENALTY_N1 = 3; static const int PENALTY_N2 = 3; static const int PENALTY_N3 = 40; static const int PENALTY_N4 = 10; /*---- High-level QR Code encoding functions ----*/ // Public function - see documentation comment in header file. bool qrcodegen_encodeText(const char *text, uint8_t tempBuffer[], uint8_t qrcode[], enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl) { size_t textLen = strlen(text); if (textLen == 0) { return qrcodegen_encodeSegmentsAdvanced(NULL, 0, ecl, minVersion, maxVersion, mask, boostEcl, tempBuffer, qrcode); }{...} size_t bufLen = (size_t)qrcodegen_BUFFER_LEN_FOR_VERSION(maxVersion); struct qrcodegen_Segment seg; if (qrcodegen_isNumeric(text)) { if (qrcodegen_calcSegmentBufferSize(qrcodegen_Mode_NUMERIC, textLen) > bufLen) { goto fail; }{...} seg = qrcodegen_makeNumeric(text, tempBuffer); }{...} else if (qrcodegen_isAlphanumeric(text)) { if (qrcodegen_calcSegmentBufferSize(qrcodegen_Mode_ALPHANUMERIC, textLen) > bufLen) { goto fail; }{...} seg = qrcodegen_makeAlphanumeric(text, tempBuffer); }{...} else { if (textLen > bufLen) { goto fail; }{...} for (size_t i = 0; i < textLen; i++) { tempBuffer[i] = (uint8_t)text[i]; }{...} seg.mode = qrcodegen_Mode_BYTE; seg.bitLength = calcSegmentBitLength(seg.mode, textLen); if (seg.bitLength == -1) { goto fail; }{...} seg.numChars = (int)textLen; seg.data = tempBuffer; }{...} return qrcodegen_encodeSegmentsAdvanced(&seg, 1, ecl, minVersion, maxVersion, mask, boostEcl, tempBuffer, qrcode); fail: qrcode[0] = 0; // Set size to invalid value for safety return false; }{ ... } // Public function - see documentation comment in header file. bool qrcodegen_encodeBinary(uint8_t dataAndTemp[], size_t dataLen, uint8_t qrcode[], enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl) { struct qrcodegen_Segment seg; seg.mode = qrcodegen_Mode_BYTE; seg.bitLength = calcSegmentBitLength(seg.mode, dataLen); if (seg.bitLength == -1) { qrcode[0] = 0; // Set size to invalid value for safety return false; }{...} seg.numChars = (int)dataLen; seg.data = dataAndTemp; return qrcodegen_encodeSegmentsAdvanced(&seg, 1, ecl, minVersion, maxVersion, mask, boostEcl, dataAndTemp, qrcode); }{ ... } // Appends the given number of low-order bits of the given value to the given byte-based // bit buffer, increasing the bit length. Requires 0 <= numBits <= 16 and val < 2^numBits. testable void appendBitsToBuffer(unsigned int val, int numBits, uint8_t buffer[], int *bitLen) { assert(0 <= numBits && numBits <= 16 && (unsigned long)val >> numBits == 0); for (int i = numBits - 1; i >= 0; i--, (*bitLen)++) { buffer[*bitLen >> 3] |= ((val >> i) & 1) << (7 - (*bitLen & 7)); }{...} }{ ... } /*---- Low-level QR Code encoding functions ----*/ // Public function - see documentation comment in header file. bool qrcodegen_encodeSegments(const struct qrcodegen_Segment segs[], size_t len, enum qrcodegen_Ecc ecl, uint8_t tempBuffer[], uint8_t qrcode[]) { return qrcodegen_encodeSegmentsAdvanced(segs, len, ecl, qrcodegen_VERSION_MIN, qrcodegen_VERSION_MAX, qrcodegen_Mask_AUTO, true, tempBuffer, qrcode); }{ ... } // Public function - see documentation comment in header file. bool qrcodegen_encodeSegmentsAdvanced(const struct qrcodegen_Segment segs[], size_t len, enum qrcodegen_Ecc ecl, int minVersion, int maxVersion, enum qrcodegen_Mask mask, bool boostEcl, uint8_t tempBuffer[], uint8_t qrcode[]) { assert(segs != NULL || len == 0); assert(qrcodegen_VERSION_MIN <= minVersion && minVersion <= maxVersion && maxVersion <= qrcodegen_VERSION_MAX); assert(0 <= (int)ecl && (int)ecl <= 3 && -1 <= (int)mask && (int)mask <= 7); // Find the minimal version number to use int version, dataUsedBits; for (version = minVersion; ; version++) { int dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available dataUsedBits = getTotalBits(segs, len, version); if (dataUsedBits != -1 && 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 qrcode[0] = 0; // Set size to invalid value for safety return false; }{...} }{...} assert(dataUsedBits != -1); // Increase the error correction level while the data still fits in the current version number for (int i = (int)qrcodegen_Ecc_MEDIUM; i <= (int)qrcodegen_Ecc_HIGH; i++) { // From low to high if (boostEcl && dataUsedBits <= getNumDataCodewords(version, (enum qrcodegen_Ecc)i) * 8) { ecl = (enum qrcodegen_Ecc)i; }{...} }{...} // Concatenate all segments to create the data bit string memset(qrcode, 0, (size_t)qrcodegen_BUFFER_LEN_FOR_VERSION(version) * sizeof(qrcode[0])); int bitLen = 0; for (size_t i = 0; i < len; i++) { const struct qrcodegen_Segment *seg = &segs[i]; appendBitsToBuffer((unsigned int)seg->mode, 4, qrcode, &bitLen); appendBitsToBuffer((unsigned int)seg->numChars, numCharCountBits(seg->mode, version), qrcode, &bitLen); for (int j = 0; j < seg->bitLength; j++) { int bit = (seg->data[j >> 3] >> (7 - (j & 7))) & 1; appendBitsToBuffer((unsigned int)bit, 1, qrcode, &bitLen); }{...} }{...} assert(bitLen == dataUsedBits); // Add terminator and pad up to a byte if applicable int dataCapacityBits = getNumDataCodewords(version, ecl) * 8; assert(bitLen <= dataCapacityBits); int terminatorBits = dataCapacityBits - bitLen; if (terminatorBits > 4) { terminatorBits = 4; }{...} appendBitsToBuffer(0, terminatorBits, qrcode, &bitLen); appendBitsToBuffer(0, (8 - bitLen % 8) % 8, qrcode, &bitLen); assert(bitLen % 8 == 0); // Pad with alternating bytes until data capacity is reached for (uint8_t padByte = 0xEC; bitLen < dataCapacityBits; padByte ^= 0xEC ^ 0x11) { appendBitsToBuffer(padByte, 8, qrcode, &bitLen); }{...} // Draw function and data codeword modules addEccAndInterleave(qrcode, version, ecl, tempBuffer); initializeFunctionModules(version, qrcode); drawCodewords(tempBuffer, getNumRawDataModules(version) / 8, qrcode); drawWhiteFunctionModules(qrcode, version); initializeFunctionModules(version, tempBuffer); // Handle masking if (mask == qrcodegen_Mask_AUTO) { // Automatically choose best mask long minPenalty = LONG_MAX; for (int i = 0; i < 8; i++) { enum qrcodegen_Mask msk = (enum qrcodegen_Mask)i; applyMask(tempBuffer, qrcode, msk); drawFormatBits(ecl, msk, qrcode); long penalty = getPenaltyScore(qrcode); if (penalty < minPenalty) { mask = msk; minPenalty = penalty; }{...} applyMask(tempBuffer, qrcode, msk); // Undoes the mask due to XOR }{...} }{...} assert(0 <= (int)mask && (int)mask <= 7); applyMask(tempBuffer, qrcode, mask); drawFormatBits(ecl, mask, qrcode); return true; }{ ... } /*---- Error correction code generation functions ----*/ // 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 : dataLen] contains // the input data. data[dataLen : rawCodewords] is used as a temporary work area and will // be clobbered by this function. The final answer is stored in result[0 : rawCodewords]. testable void addEccAndInterleave(uint8_t data[], int version, enum qrcodegen_Ecc ecl, uint8_t result[]) { // Calculate parameter numbers assert(0 <= (int)ecl && (int)ecl < 4 && qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX); int numBlocks = NUM_ERROR_CORRECTION_BLOCKS[(int)ecl][version]; int blockEccLen = ECC_CODEWORDS_PER_BLOCK [(int)ecl][version]; int rawCodewords = getNumRawDataModules(version) / 8; int dataLen = getNumDataCodewords(version, ecl); int numShortBlocks = numBlocks - rawCodewords % numBlocks; int shortBlockDataLen = rawCodewords / numBlocks - blockEccLen; // Split data into blocks, calculate ECC, and interleave // (not concatenate) the bytes into a single sequence uint8_t rsdiv[qrcodegen_REED_SOLOMON_DEGREE_MAX]; reedSolomonComputeDivisor(blockEccLen, rsdiv); const uint8_t *dat = data; for (int i = 0; i < numBlocks; i++) { int datLen = shortBlockDataLen + (i < numShortBlocks ? 0 : 1); uint8_t *ecc = &data[dataLen]; // Temporary storage reedSolomonComputeRemainder(dat, datLen, rsdiv, blockEccLen, ecc); for (int j = 0, k = i; j < datLen; j++, k += numBlocks) { // Copy data if (j == shortBlockDataLen) { k -= numShortBlocks; }{...} result[k] = dat[j]; }{...} for (int j = 0, k = dataLen + i; j < blockEccLen; j++, k += numBlocks) { // Copy ECC result[k] = ecc[j]; }{...} dat += datLen; }{...} }{ ... } // 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]. testable int getNumDataCodewords(int version, enum qrcodegen_Ecc ecl) { int v = version, e = (int)ecl; assert(0 <= e && e < 4); return getNumRawDataModules(v) / 8 - ECC_CODEWORDS_PER_BLOCK [e][v] * NUM_ERROR_CORRECTION_BLOCKS[e][v]; }{ ... } // 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 might not be a multiple of 8. // The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table. testable int getNumRawDataModules(int ver) { assert(qrcodegen_VERSION_MIN <= ver && ver <= qrcodegen_VERSION_MAX); int result = (16 * ver + 128) * ver + 64; if (ver >= 2) { int numAlign = ver / 7 + 2; result -= (25 * numAlign - 10) * numAlign - 55; if (ver >= 7) { result -= 36; }{...} }{...} assert(208 <= result && result <= 29648); return result; }{ ... } /*---- Reed-Solomon ECC generator functions ----*/ // Computes a Reed-Solomon ECC generator polynomial for the given degree, storing in result[0 : degree]. // This could be implemented as a lookup table over all possible parameter values, instead of as an algorithm. testable void reedSolomonComputeDivisor(int degree, uint8_t result[]) { assert(1 <= degree && degree <= qrcodegen_REED_SOLOMON_DEGREE_MAX); // Polynomial coefficients are stored from highest to lowest power, excluding the leading term which is always 1. // For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8 array {255, 8, 93}. memset(result, 0, (size_t)degree * sizeof(result[0])); result[degree - 1] = 1; // Start off with the monomial x^0 // Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}), // drop the highest monomial term which is always 1x^degree. // Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D). uint8_t 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] = reedSolomonMultiply(result[j], root); if (j + 1 < degree) { result[j] ^= result[j + 1]; }{...} }{...} root = reedSolomonMultiply(root, 0x02); }{...} }{ ... } // Computes the Reed-Solomon error correction codeword for the given data and divisor polynomials. // The remainder when data[0 : dataLen] is divided by divisor[0 : degree] is stored in result[0 : degree]. // All polynomials are in big endian, and the generator has an implicit leading 1 term. testable void reedSolomonComputeRemainder(const uint8_t data[], int dataLen, const uint8_t generator[], int degree, uint8_t result[]) { assert(1 <= degree && degree <= qrcodegen_REED_SOLOMON_DEGREE_MAX); memset(result, 0, (size_t)degree * sizeof(result[0])); for (int i = 0; i < dataLen; i++) { // Polynomial division uint8_t factor = data[i] ^ result[0]; memmove(&result[0], &result[1], (size_t)(degree - 1) * sizeof(result[0])); result[degree - 1] = 0; for (int j = 0; j < degree; j++) { result[j] ^= reedSolomonMultiply(generator[j], factor); }{...} }{...} }{ ... } #undef qrcodegen_REED_SOLOMON_DEGREE_MAX // Returns the product of the two given field elements modulo GF(2^8/0x11D). // All inputs are valid. This could be implemented as a 256*256 lookup table. testable uint8_t reedSolomonMultiply(uint8_t x, uint8_t y) { // Russian peasant multiplication uint8_t z = 0; for (int i = 7; i >= 0; i--) { z = (uint8_t)((z << 1) ^ ((z >> 7) * 0x11D)); z ^= ((y >> i) & 1) * x; }{...} return z; }{ ... } /*---- Drawing function modules ----*/ // Clears the given QR Code grid with white modules for the given // version's size, then marks every function module as black. testable void initializeFunctionModules(int version, uint8_t qrcode[]) { // Initialize QR Code int qrsize = version * 4 + 17; memset(qrcode, 0, (size_t)((qrsize * qrsize + 7) / 8 + 1) * sizeof(qrcode[0])); qrcode[0] = (uint8_t)qrsize; // Fill horizontal and vertical timing patterns fillRectangle(6, 0, 1, qrsize, qrcode); fillRectangle(0, 6, qrsize, 1, qrcode); // Fill 3 finder patterns (all corners except bottom right) and format bits fillRectangle(0, 0, 9, 9, qrcode); fillRectangle(qrsize - 8, 0, 8, 9, qrcode); fillRectangle(0, qrsize - 8, 9, 8, qrcode); // Fill numerous alignment patterns uint8_t alignPatPos[7]; int numAlign = getAlignmentPatternPositions(version, alignPatPos); for (int i = 0; i < numAlign; i++) { for (int j = 0; j < numAlign; j++) { // Don't draw on the three finder corners if (!((i == 0 && j == 0) || (i == 0 && j == numAlign - 1) || (i == numAlign - 1 && j == 0))) { fillRectangle(alignPatPos[i] - 2, alignPatPos[j] - 2, 5, 5, qrcode); }{...} }{...} }{...} // Fill version blocks if (version >= 7) { fillRectangle(qrsize - 11, 0, 3, 6, qrcode); fillRectangle(0, qrsize - 11, 6, 3, qrcode); }{...} }{ ... } // 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 initializeFunctionModules()), because this may skip redrawing black function modules. static void drawWhiteFunctionModules(uint8_t qrcode[], int version) { // Draw horizontal and vertical timing patterns int qrsize = qrcodegen_getSize(qrcode); for (int i = 7; i < qrsize - 7; i += 2) { setModule(qrcode, 6, i, false); setModule(qrcode, i, 6, false); }{...} // Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules) for (int dy = -4; dy <= 4; dy++) { for (int dx = -4; dx <= 4; dx++) { int dist = abs(dx); if (abs(dy) > dist) { dist = abs(dy); }{...} if (dist == 2 || dist == 4) { setModuleBounded(qrcode, 3 + dx, 3 + dy, false); setModuleBounded(qrcode, qrsize - 4 + dx, 3 + dy, false); setModuleBounded(qrcode, 3 + dx, qrsize - 4 + dy, false); }{...} }{...} }{...} // Draw numerous alignment patterns uint8_t alignPatPos[7]; 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; // Don't draw on the three finder corners }{...} for (int dy = -1; dy <= 1; dy++) { for (int dx = -1; dx <= 1; dx++) { setModule(qrcode, alignPatPos[i] + dx, alignPatPos[j] + dy, dx == 0 && dy == 0); }{...} }{...} }{...} }{...} // Draw version blocks 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 bits = (long)version << 12 | rem; // uint18 assert(bits >> 18 == 0); // Draw two copies for (int i = 0; i < 6; i++) { for (int j = 0; j < 3; j++) { int k = qrsize - 11 + j; setModule(qrcode, k, i, (bits & 1) != 0); setModule(qrcode, i, k, (bits & 1) != 0); bits >>= 1; }{...} }{...} }{...} }{ ... } // Draws two copies of the format bits (with its own error correction code) based // on the given mask and error correction level. This always draws all modules of // the format bits, unlike drawWhiteFunctionModules() which might skip black modules. static void drawFormatBits(enum qrcodegen_Ecc ecl, enum qrcodegen_Mask mask, uint8_t qrcode[]) { // Calculate error correction code and pack bits assert(0 <= (int)mask && (int)mask <= 7); static const int table[] = {1, 0, 3, 2}; int data = table[(int)ecl] << 3 | (int)mask; // errCorrLvl is uint2, mask is uint3 int rem = data; for (int i = 0; i < 10; i++) { rem = (rem << 1) ^ ((rem >> 9) * 0x537); }{...} int bits = (data << 10 | rem) ^ 0x5412; // uint15 assert(bits >> 15 == 0); // Draw first copy for (int i = 0; i <= 5; i++) { setModule(qrcode, 8, i, getBit(bits, i)); }{...} setModule(qrcode, 8, 7, getBit(bits, 6)); setModule(qrcode, 8, 8, getBit(bits, 7)); setModule(qrcode, 7, 8, getBit(bits, 8)); for (int i = 9; i < 15; i++) { setModule(qrcode, 14 - i, 8, getBit(bits, i)); }{...} // Draw second copy int qrsize = qrcodegen_getSize(qrcode); for (int i = 0; i < 8; i++) { setModule(qrcode, qrsize - 1 - i, 8, getBit(bits, i)); }{...} for (int i = 8; i < 15; i++) { setModule(qrcode, 8, qrsize - 15 + i, getBit(bits, i)); }{...} setModule(qrcode, 8, qrsize - 8, true); // Always black }{ ... } // Calculates and stores an ascending list of positions of alignment patterns // for this version number, returning the length of the list (in the range [0,7]). // Each position is in the range [0,177), and are used on both the x and y axes. // This could be implemented as lookup table of 40 variable-length lists of unsigned bytes. testable int getAlignmentPatternPositions(int version, uint8_t result[7]) { if (version == 1) { return 0; }{...} int numAlign = version / 7 + 2; int step = (version == 32) ? 26 : (version * 4 + numAlign * 2 + 1) / (numAlign * 2 - 2) * 2; for (int i = numAlign - 1, pos = version * 4 + 10; i >= 1; i--, pos -= step) { result[i] = (uint8_t)pos; }{...} result[0] = 6; return numAlign; }{ ... } // Sets every pixel in the range [left : left + width] * [top : top + height] to black. static void fillRectangle(int left, int top, int width, int height, uint8_t qrcode[]) { for (int dy = 0; dy < height; dy++) { for (int dx = 0; dx < width; dx++) { setModule(qrcode, left + dx, top + dy, true); }{...} }{...} }{ ... } /*---- Drawing data modules and masking ----*/ // 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). static void drawCodewords(const uint8_t data[], int dataLen, uint8_t qrcode[]) { int qrsize = qrcodegen_getSize(qrcode); int i = 0; // Bit index into the data // Do the funny zigzag scan for (int right = qrsize - 1; right >= 1; right -= 2) { // Index of right column in each column pair if (right == 6) { right = 5; }{...} for (int vert = 0; vert < qrsize; vert++) { // Vertical counter for (int j = 0; j < 2; j++) { int x = right - j; // Actual x coordinate bool upward = ((right + 1) & 2) == 0; int y = upward ? qrsize - 1 - vert : vert; // Actual y coordinate if (!getModule(qrcode, x, y) && i < dataLen * 8) { bool black = getBit(data[i >> 3], 7 - (i & 7)); setModule(qrcode, x, y, black); i++; }{...} // If this QR Code has any remainder bits (0 to 7), they were assigned as // 0/false/white by the constructor and are left unchanged by this method }{...} }{...} }{...} assert(i == dataLen * 8); }{ ... } // XORs the codeword modules in this QR Code with the given mask pattern. // The function modules must be marked and the codeword bits must be drawn // before masking. Due to the arithmetic of XOR, calling applyMask() with // the same mask value a second time will undo the mask. A final well-formed // QR Code needs exactly one (not zero, two, etc.) mask applied. static void applyMask(const uint8_t functionModules[], uint8_t qrcode[], enum qrcodegen_Mask mask) { assert(0 <= (int)mask && (int)mask <= 7); // Disallows qrcodegen_Mask_AUTO int qrsize = qrcodegen_getSize(qrcode); for (int y = 0; y < qrsize; y++) { for (int x = 0; x < qrsize; x++) { if (getModule(functionModules, x, y)) { continue; }{...} bool invert; switch ((int)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); return; }{...} bool val = getModule(qrcode, x, y); setModule(qrcode, x, y, val ^ invert); }{...} }{...} }{ ... } // 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 qrsize = qrcodegen_getSize(qrcode); long result = 0; // Adjacent modules in row having same color, and finder-like patterns for (int y = 0; y < qrsize; y++) { bool runColor = false; int runX = 0; int runHistory[7] = {0}; int padRun = qrsize; // Add white border to initial run for (int x = 0; x < qrsize; x++) { if (getModule(qrcode, x, y) == runColor) { runX++; if (runX == 5) { result += PENALTY_N1; }{...} else if (runX > 5) { result++; }{...} }{...} else { finderPenaltyAddHistory(runX + padRun, runHistory); padRun = 0; if (!runColor) { result += finderPenaltyCountPatterns(runHistory, qrsize) * PENALTY_N3; }{...} runColor = getModule(qrcode, x, y); runX = 1; }{...} }{...} result += finderPenaltyTerminateAndCount(runColor, runX + padRun, runHistory, qrsize) * PENALTY_N3; }{...} // Adjacent modules in column having same color, and finder-like patterns for (int x = 0; x < qrsize; x++) { bool runColor = false; int runY = 0; int runHistory[7] = {0}; int padRun = qrsize; // Add white border to initial run for (int y = 0; y < qrsize; y++) { if (getModule(qrcode, x, y) == runColor) { runY++; if (runY == 5) { result += PENALTY_N1; }{...} else if (runY > 5) { result++; }{...} }{...} else { finderPenaltyAddHistory(runY + padRun, runHistory); padRun = 0; if (!runColor) { result += finderPenaltyCountPatterns(runHistory, qrsize) * PENALTY_N3; }{...} runColor = getModule(qrcode, x, y); runY = 1; }{...} }{...} result += finderPenaltyTerminateAndCount(runColor, runY + padRun, runHistory, qrsize) * PENALTY_N3; }{...} // 2*2 blocks of modules having same color for (int y = 0; y < qrsize - 1; y++) { for (int x = 0; x < qrsize - 1; x++) { bool color = getModule(qrcode, x, y); if ( color == getModule(qrcode, x + 1, y) && color == getModule(qrcode, x, y + 1) && color == getModule(qrcode, x + 1, y + 1)) { result += PENALTY_N2; }{...} }{...} }{...} // Balance of black and white modules int black = 0; for (int y = 0; y < qrsize; y++) { for (int x = 0; x < qrsize; x++) { if (getModule(qrcode, x, y)) { black++; }{...} }{...} }{...} int total = qrsize * qrsize; // Note that size is odd, so black/total != 1/2 // Compute the smallest integer k >= 0 such that (45-5k)% <= black/total <= (55+5k)% int k = (int)((labs(black * 20L - total * 10L) + total - 1) / total) - 1; result += k * PENALTY_N4; return result; }{ ... } // Can only be called immediately after a white run is added, and // returns either 0, 1, or 2. A helper function for getPenaltyScore(). static int finderPenaltyCountPatterns(const int runHistory[7], int qrsize) { int n = runHistory[1]; assert(n <= qrsize * 3); bool core = n > 0 && runHistory[2] == n && runHistory[3] == n * 3 && runHistory[4] == n && runHistory[5] == n; // The maximum QR Code size is 177, hence the black run length n <= 177. // Arithmetic is promoted to int, so n*4 will not overflow. return (core && runHistory[0] >= n * 4 && runHistory[6] >= n ? 1 : 0) + (core && runHistory[6] >= n * 4 && runHistory[0] >= n ? 1 : 0); }{ ... } // Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore(). static int finderPenaltyTerminateAndCount(bool currentRunColor, int currentRunLength, int runHistory[7], int qrsize) { if (currentRunColor) { // Terminate black run finderPenaltyAddHistory(currentRunLength, runHistory); currentRunLength = 0; }{...} currentRunLength += qrsize; // Add white border to final run finderPenaltyAddHistory(currentRunLength, runHistory); return finderPenaltyCountPatterns(runHistory, qrsize); }{ ... } // Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore(). static void finderPenaltyAddHistory(int currentRunLength, int runHistory[7]) { memmove(&runHistory[1], &runHistory[0], 6 * sizeof(runHistory[0])); runHistory[0] = currentRunLength; }{ ... } /*---- Basic QR Code information ----*/ // Public function - see documentation comment in header file. int qrcodegen_getSize(const uint8_t qrcode[]) { assert(qrcode != NULL); int result = qrcode[0]; assert((qrcodegen_VERSION_MIN * 4 + 17) <= result && result <= (qrcodegen_VERSION_MAX * 4 + 17)); return result; }{ ... } // Public function - see documentation comment in header file. bool qrcodegen_getModule(const uint8_t qrcode[], int x, int y) { assert(qrcode != NULL); int qrsize = qrcode[0]; return (0 <= x && x < qrsize && 0 <= y && y < qrsize) && getModule(qrcode, x, y); }{ ... } // Gets the module at the given coordinates, which must be in bounds. testable bool getModule(const uint8_t qrcode[], int x, int y) { int qrsize = qrcode[0]; assert(21 <= qrsize && qrsize <= 177 && 0 <= x && x < qrsize && 0 <= y && y < qrsize); int index = y * qrsize + x; return getBit(qrcode[(index >> 3) + 1], index & 7); }{ ... } // Sets the module at the given coordinates, which must be in bounds. testable void setModule(uint8_t qrcode[], int x, int y, bool isBlack) { int qrsize = qrcode[0]; assert(21 <= qrsize && qrsize <= 177 && 0 <= x && x < qrsize && 0 <= y && y < qrsize); int index = y * qrsize + x; int bitIndex = index & 7; int byteIndex = (index >> 3) + 1; 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. testable void setModuleBounded(uint8_t qrcode[], int x, int y, bool isBlack) { int qrsize = qrcode[0]; if (0 <= x && x < qrsize && 0 <= y && y < qrsize) { setModule(qrcode, x, y, isBlack); }{...} }{ ... } // Returns true iff the i'th bit of x is set to 1. Requires x >= 0 and 0 <= i <= 14. static bool getBit(int x, int i) { return ((x >> i) & 1) != 0; }{ ... } /*---- Segment handling ----*/ // Public function - see documentation comment in header file. bool qrcodegen_isAlphanumeric(const char *text) { assert(text != NULL); for (; *text != '\0'; text++) { if (strchr(ALPHANUMERIC_CHARSET, *text) == NULL) { return false; }{...} }{...} return true; }{ ... } // Public function - see documentation comment in header file. bool qrcodegen_isNumeric(const char *text) { assert(text != NULL); for (; *text != '\0'; text++) { if (*text < '0' || *text > '9') { return false; }{...} }{...} return true; }{ ... } // Public function - see documentation comment in header file. size_t qrcodegen_calcSegmentBufferSize(enum qrcodegen_Mode mode, size_t numChars) { int temp = calcSegmentBitLength(mode, numChars); if (temp == -1) { return SIZE_MAX; }{...} assert(0 <= temp && temp <= INT16_MAX); return ((size_t)temp + 7) / 8; }{ ... } // Returns the number of data bits needed to represent a segment // containing the given number of characters using the given mode. Notes: // - Returns -1 on failure, i.e. numChars > INT16_MAX or // the number of needed bits exceeds INT16_MAX (i.e. 32767). // - Otherwise, all valid results are in the range [0, INT16_MAX]. // - For byte mode, numChars measures the number of bytes, not Unicode code points. // - For ECI mode, numChars must be 0, and the worst-case number of bits is returned. // An actual ECI segment can have shorter data. For non-ECI modes, the result is exact. testable int calcSegmentBitLength(enum qrcodegen_Mode mode, size_t numChars) { // All calculations are designed to avoid overflow on all platforms if (numChars > (unsigned int)INT16_MAX) { return -1; }{...} long result = (long)numChars; if (mode == qrcodegen_Mode_NUMERIC) { result = (result * 10 + 2) / 3; // ceil(10/3 * n) }{...} else if (mode == qrcodegen_Mode_ALPHANUMERIC) { result = (result * 11 + 1) / 2; // ceil(11/2 * n) }{...} else if (mode == qrcodegen_Mode_BYTE) { result *= 8; }{...} else if (mode == qrcodegen_Mode_KANJI) { result *= 13; }{...} else if (mode == qrcodegen_Mode_ECI && numChars == 0) { result = 3 * 8; }{...} else { // Invalid argument assert(false); return -1; }{...} assert(result >= 0); if (result > INT16_MAX) { return -1; }{...} return (int)result; }{ ... } // Public function - see documentation comment in header file. struct qrcodegen_Segment qrcodegen_makeBytes(const uint8_t data[], size_t len, uint8_t buf[]) { assert(data != NULL || len == 0); struct qrcodegen_Segment result; result.mode = qrcodegen_Mode_BYTE; result.bitLength = calcSegmentBitLength(result.mode, len); assert(result.bitLength != -1); result.numChars = (int)len; if (len > 0) { memcpy(buf, data, len * sizeof(buf[0])); }{...} result.data = buf; return result; }{...} // Public function - see documentation comment in header file. struct qrcodegen_Segment qrcodegen_makeNumeric(const char *digits, uint8_t buf[]) { assert(digits != NULL); struct qrcodegen_Segment result; size_t len = strlen(digits); result.mode = qrcodegen_Mode_NUMERIC; int bitLen = calcSegmentBitLength(result.mode, len); assert(bitLen != -1); result.numChars = (int)len; if (bitLen > 0) { memset(buf, 0, ((size_t)bitLen + 7) / 8 * sizeof(buf[0])); }{...} result.bitLength = 0; unsigned int accumData = 0; int accumCount = 0; for (; *digits != '\0'; digits++) { char c = *digits; assert('0' <= c && c <= '9'); accumData = accumData * 10 + (unsigned int)(c - '0'); accumCount++; if (accumCount == 3) { appendBitsToBuffer(accumData, 10, buf, &result.bitLength); accumData = 0; accumCount = 0; }{...} }{...} if (accumCount > 0) { // 1 or 2 digits remaining appendBitsToBuffer(accumData, accumCount * 3 + 1, buf, &result.bitLength); }{...} assert(result.bitLength == bitLen); result.data = buf; return result; }{...} // Public function - see documentation comment in header file. struct qrcodegen_Segment qrcodegen_makeAlphanumeric(const char *text, uint8_t buf[]) { assert(text != NULL); struct qrcodegen_Segment result; size_t len = strlen(text); result.mode = qrcodegen_Mode_ALPHANUMERIC; int bitLen = calcSegmentBitLength(result.mode, len); assert(bitLen != -1); result.numChars = (int)len; if (bitLen > 0) { memset(buf, 0, ((size_t)bitLen + 7) / 8 * sizeof(buf[0])); }{...} result.bitLength = 0; unsigned int accumData = 0; int accumCount = 0; for (; *text != '\0'; text++) { const char *temp = strchr(ALPHANUMERIC_CHARSET, *text); assert(temp != NULL); accumData = accumData * 45 + (unsigned int)(temp - ALPHANUMERIC_CHARSET); accumCount++; if (accumCount == 2) { appendBitsToBuffer(accumData, 11, buf, &result.bitLength); accumData = 0; accumCount = 0; }{...} }{...} if (accumCount > 0) { // 1 character remaining appendBitsToBuffer(accumData, 6, buf, &result.bitLength); }{...} assert(result.bitLength == bitLen); result.data = buf; return result; }{...} // Public function - see documentation comment in header file. struct qrcodegen_Segment qrcodegen_makeEci(long assignVal, uint8_t buf[]) { struct qrcodegen_Segment result; result.mode = qrcodegen_Mode_ECI; result.numChars = 0; result.bitLength = 0; if (assignVal < 0) { assert(false); }{...} else if (assignVal < (1 << 7)) { memset(buf, 0, 1 * sizeof(buf[0])); appendBitsToBuffer((unsigned int)assignVal, 8, buf, &result.bitLength); }{...} else if (assignVal < (1 << 14)) { memset(buf, 0, 2 * sizeof(buf[0])); appendBitsToBuffer(2, 2, buf, &result.bitLength); appendBitsToBuffer((unsigned int)assignVal, 14, buf, &result.bitLength); }{...} else if (assignVal < 1000000L) { memset(buf, 0, 3 * sizeof(buf[0])); appendBitsToBuffer(6, 3, buf, &result.bitLength); appendBitsToBuffer((unsigned int)(assignVal >> 10), 11, buf, &result.bitLength); appendBitsToBuffer((unsigned int)(assignVal & 0x3FF), 10, buf, &result.bitLength); }{...} else { assert(false); }{...} result.data = buf; return result; }{...} // Calculates the number of bits needed to encode the given segments at the given version. // Returns a non-negative number if successful. Otherwise returns -1 if a segment has too // many characters to fit its length field, or the total bits exceeds INT16_MAX. testable int getTotalBits(const struct qrcodegen_Segment segs[], size_t len, int version) { assert(segs != NULL || len == 0); long result = 0; for (size_t i = 0; i < len; i++) { int numChars = segs[i].numChars; int bitLength = segs[i].bitLength; assert(0 <= numChars && numChars <= INT16_MAX); assert(0 <= bitLength && bitLength <= INT16_MAX); int ccbits = numCharCountBits(segs[i].mode, version); assert(0 <= ccbits && ccbits <= 16); if (numChars >= (1L << ccbits)) { return -1; // The segment's length doesn't fit the field's bit width }{...} result += 4L + ccbits + bitLength; if (result > INT16_MAX) { return -1; // The sum might overflow an int type }{...} }{...} assert(0 <= result && result <= INT16_MAX); return (int)result; }{ ... } // Returns the bit width of the character count field for a segment in the given mode // in a QR Code at the given version number. The result is in the range [0, 16]. static int numCharCountBits(enum qrcodegen_Mode mode, int version) { assert(qrcodegen_VERSION_MIN <= version && version <= qrcodegen_VERSION_MAX); int i = (version + 7) / 17; switch (mode) { case qrcodegen_Mode_NUMERIC : { static const int temp[] = {10, 12, 14}; return temp[i]; }{...} ... case qrcodegen_Mode_ALPHANUMERIC: { static const int temp[] = { 9, 11, 13}; return temp[i]; }{...} ... case qrcodegen_Mode_BYTE : { static const int temp[] = { 8, 16, 16}; return temp[i]; }{...} ... case qrcodegen_Mode_KANJI : { static const int temp[] = { 8, 10, 12}; return temp[i]; }{...} ... case qrcodegen_Mode_ECI : return 0; default: assert(false); return -1; // Dummy value }{...} }{ ... }