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Diffstat (limited to 'clients/common/qrcodegen.c')
| -rw-r--r-- | clients/common/qrcodegen.c | 1009 |
1 files changed, 1009 insertions, 0 deletions
diff --git a/clients/common/qrcodegen.c b/clients/common/qrcodegen.c new file mode 100644 index 00000000..7cda9659 --- /dev/null +++ b/clients/common/qrcodegen.c @@ -0,0 +1,1009 @@ +/* + * 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" + +#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 calcReedSolomonGenerator(int degree, uint8_t result[]); +testable void calcReedSolomonRemainder(const uint8_t data[], int dataLen, + const uint8_t generator[], int degree, uint8_t result[]); +testable uint8_t finiteFieldMultiply(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 void addRunToHistory(unsigned char run, unsigned char history[7]); +static bool hasFinderLikePattern(unsigned char 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 = 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, -1, 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, int 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, 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((int)seg->mode, 4, qrcode, &bitLen); + appendBitsToBuffer(seg->numChars, numCharCountBits(seg->mode, version), qrcode, &bitLen); + for (int j = 0; j < seg->bitLength; j++) + appendBitsToBuffer((seg->data[j >> 3] >> (7 - (j & 7))) & 1, 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; + drawFormatBits(ecl, msk, qrcode); + applyMask(tempBuffer, qrcode, msk); + 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); + drawFormatBits(ecl, mask, qrcode); + applyMask(tempBuffer, qrcode, mask); + 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 generator[qrcodegen_REED_SOLOMON_DEGREE_MAX]; + calcReedSolomonGenerator(blockEccLen, generator); + 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 + calcReedSolomonRemainder(dat, datLen, generator, 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; + } + return result; +} + + + +/*---- Reed-Solomon ECC generator functions ----*/ + +// Calculates the Reed-Solomon generator polynomial of the given degree, storing in result[0 : degree]. +testable void calcReedSolomonGenerator(int degree, uint8_t result[]) { + // Start with the monomial x^0 + assert(1 <= degree && degree <= qrcodegen_REED_SOLOMON_DEGREE_MAX); + 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). + 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] = finiteFieldMultiply(result[j], root); + if (j + 1 < degree) + result[j] ^= result[j + 1]; + } + root = finiteFieldMultiply(root, 0x02); + } +} + + +// 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]. +testable void calcReedSolomonRemainder(const uint8_t data[], int dataLen, + const uint8_t generator[], int degree, uint8_t result[]) { + + // Perform polynomial division + assert(1 <= degree && degree <= qrcodegen_REED_SOLOMON_DEGREE_MAX); + 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); + } +} + +#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 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; +} + + + +/*---- 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, ((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] = 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++) { + unsigned char runHistory[7] = {0}; + bool color = false; + unsigned char runX = 0; + for (int x = 0; x < qrsize; x++) { + if (getModule(qrcode, x, y) == color) { + runX++; + if (runX == 5) + result += PENALTY_N1; + else if (runX > 5) + result++; + } else { + addRunToHistory(runX, runHistory); + if (!color && hasFinderLikePattern(runHistory)) + result += PENALTY_N3; + color = getModule(qrcode, x, y); + runX = 1; + } + } + addRunToHistory(runX, runHistory); + if (color) + addRunToHistory(0, runHistory); // Dummy run of white + if (hasFinderLikePattern(runHistory)) + result += PENALTY_N3; + } + // Adjacent modules in column having same color, and finder-like patterns + for (int x = 0; x < qrsize; x++) { + unsigned char runHistory[7] = {0}; + bool color = false; + unsigned char runY = 0; + for (int y = 0; y < qrsize; y++) { + if (getModule(qrcode, x, y) == color) { + runY++; + if (runY == 5) + result += PENALTY_N1; + else if (runY > 5) + result++; + } else { + addRunToHistory(runY, runHistory); + if (!color && hasFinderLikePattern(runHistory)) + result += PENALTY_N3; + color = getModule(qrcode, x, y); + runY = 1; + } + } + addRunToHistory(runY, runHistory); + if (color) + addRunToHistory(0, runHistory); // Dummy run of white + if (hasFinderLikePattern(runHistory)) + result += 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; +} + + +// Inserts the given value to the front of the given array, which shifts over the +// existing values and deletes the last value. A helper function for getPenaltyScore(). +static void addRunToHistory(unsigned char run, unsigned char history[7]) { + memmove(&history[1], &history[0], 6 * sizeof(history[0])); + history[0] = run; +} + + +// Tests whether the given run history has the pattern of ratio 1:1:3:1:1 in the middle, and +// surrounded by at least 4 on either or both ends. A helper function for getPenaltyScore(). +// Must only be called immediately after a run of white modules has ended. +static bool hasFinderLikePattern(unsigned char runHistory[7]) { + unsigned char n = runHistory[1]; + // The maximum QR Code size is 177, hence the run length n <= 177. + // Arithmetic is promoted to int, so n*4 will not overflow. + return n > 0 && runHistory[2] == n && runHistory[4] == n && runHistory[5] == n + && runHistory[3] == n * 3 && (runHistory[0] >= n * 4 || runHistory[6] >= n * 4); +} + + + +/*---- 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 > (unsigned int)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(assignVal, 8, buf, &result.bitLength); + } else if (assignVal < (1 << 14)) { + memset(buf, 0, 2 * sizeof(buf[0])); + appendBitsToBuffer(2, 2, buf, &result.bitLength); + appendBitsToBuffer(assignVal, 14, buf, &result.bitLength); + } else if (assignVal < 1000000L) { + memset(buf, 0, 3 * sizeof(buf[0])); + appendBitsToBuffer(6, 3, buf, &result.bitLength); + appendBitsToBuffer(assignVal >> 10, 11, buf, &result.bitLength); + appendBitsToBuffer(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 + } +} |