/* quirc -- QR-code recognition library * Copyright (C) 2010-2012 Daniel Beer * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "quirc_internal.h" #include #include #define MAX_POLY 64 /************************************************************************ * Galois fields */ struct galois_field { int p; const uint8_t *log; const uint8_t *exp; }; static const uint8_t gf16_exp[16] = { 0x01, 0x02, 0x04, 0x08, 0x03, 0x06, 0x0c, 0x0b, 0x05, 0x0a, 0x07, 0x0e, 0x0f, 0x0d, 0x09, 0x01 }; static const uint8_t gf16_log[16] = { 0x00, 0x0f, 0x01, 0x04, 0x02, 0x08, 0x05, 0x0a, 0x03, 0x0e, 0x09, 0x07, 0x06, 0x0d, 0x0b, 0x0c }; static const struct galois_field gf16 = { .p = 15, .log = gf16_log, .exp = gf16_exp }; static const uint8_t gf256_exp[256] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01 }; static const uint8_t gf256_log[256] = { 0x00, 0xff, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf }; const static struct galois_field gf256 = { .p = 255, .log = gf256_log, .exp = gf256_exp }; /************************************************************************ * Polynomial operations */ static void poly_add(uint8_t *dst, const uint8_t *src, uint8_t c, int shift, const struct galois_field *gf) { int i; int log_c = gf->log[c]; if (!c) return; for (i = 0; i < MAX_POLY; i++) { int p = i + shift; uint8_t v = src[i]; if (p < 0 || p >= MAX_POLY) continue; if (!v) continue; dst[p] ^= gf->exp[(gf->log[v] + log_c) % gf->p]; } } static uint8_t poly_eval(const uint8_t *s, uint8_t x, const struct galois_field *gf) { int i; uint8_t sum = 0; uint8_t log_x = gf->log[x]; if (!x) return s[0]; for (i = 0; i < MAX_POLY; i++) { uint8_t c = s[i]; if (!c) continue; sum ^= gf->exp[(gf->log[c] + log_x * i) % gf->p]; } return sum; } /************************************************************************ * Berlekamp-Massey algorithm for finding error locator polynomials. */ static void berlekamp_massey(const uint8_t *s, int N, const struct galois_field *gf, uint8_t *sigma) { uint8_t C[MAX_POLY]; uint8_t B[MAX_POLY]; int L = 0; int m = 1; uint8_t b = 1; int n; memset(B, 0, sizeof(B)); memset(C, 0, sizeof(C)); B[0] = 1; C[0] = 1; for (n = 0; n < N; n++) { uint8_t d = s[n]; uint8_t mult; int i; for (i = 1; i <= L; i++) { if (!(C[i] && s[n - i])) continue; d ^= gf->exp[(gf->log[C[i]] + gf->log[s[n - i]]) % gf->p]; } mult = gf->exp[(gf->p - gf->log[b] + gf->log[d]) % gf->p]; if (!d) { m++; } else if (L * 2 <= n) { uint8_t T[MAX_POLY]; memcpy(T, C, sizeof(T)); poly_add(C, B, mult, m, gf); memcpy(B, T, sizeof(B)); L = n + 1 - L; b = d; m = 1; } else { poly_add(C, B, mult, m, gf); m++; } } memcpy(sigma, C, MAX_POLY); } /************************************************************************ * Code stream error correction * * Generator polynomial for GF(2^8) is x^8 + x^4 + x^3 + x^2 + 1 */ static int block_syndromes(const uint8_t *data, int bs, int npar, uint8_t *s) { int nonzero = 0; int i; memset(s, 0, MAX_POLY); for (i = 0; i < npar; i++) { int j; for (j = 0; j < bs; j++) { uint8_t c = data[bs - j - 1]; if (!c) continue; s[i] ^= gf256_exp[((int)gf256_log[c] + i * j) % 255]; } if (s[i]) nonzero = 1; } return nonzero; } static void eloc_poly(uint8_t *omega, const uint8_t *s, const uint8_t *sigma, int npar) { int i; memset(omega, 0, MAX_POLY); for (i = 0; i < npar; i++) { const uint8_t a = sigma[i]; const uint8_t log_a = gf256_log[a]; int j; if (!a) continue; for (j = 0; j + 1 < MAX_POLY; j++) { const uint8_t b = s[j + 1]; if (i + j >= npar) break; if (!b) continue; omega[i + j] ^= gf256_exp[(log_a + gf256_log[b]) % 255]; } } } static quirc_decode_error_t correct_block(uint8_t *data, const struct quirc_rs_params *ecc) { int npar = ecc->bs - ecc->dw; uint8_t s[MAX_POLY]; uint8_t sigma[MAX_POLY]; uint8_t sigma_deriv[MAX_POLY]; uint8_t omega[MAX_POLY]; int i; /* Compute syndrome vector */ if (!block_syndromes(data, ecc->bs, npar, s)) return QUIRC_SUCCESS; berlekamp_massey(s, npar, &gf256, sigma); /* Compute derivative of sigma */ memset(sigma_deriv, 0, MAX_POLY); for (i = 0; i + 1 < MAX_POLY; i += 2) sigma_deriv[i] = sigma[i + 1]; /* Compute error evaluator polynomial */ eloc_poly(omega, s, sigma, npar - 1); /* Find error locations and magnitudes */ for (i = 0; i < ecc->bs; i++) { uint8_t xinv = gf256_exp[255 - i]; if (!poly_eval(sigma, xinv, &gf256)) { uint8_t sd_x = poly_eval(sigma_deriv, xinv, &gf256); uint8_t omega_x = poly_eval(omega, xinv, &gf256); uint8_t error = gf256_exp[(255 - gf256_log[sd_x] + gf256_log[omega_x]) % 255]; data[ecc->bs - i - 1] ^= error; } } if (block_syndromes(data, ecc->bs, npar, s)) return QUIRC_ERROR_DATA_ECC; return QUIRC_SUCCESS; } /************************************************************************ * Format value error correction * * Generator polynomial for GF(2^4) is x^4 + x + 1 */ #define FORMAT_MAX_ERROR 3 #define FORMAT_SYNDROMES (FORMAT_MAX_ERROR * 2) #define FORMAT_BITS 15 static int format_syndromes(uint16_t u, uint8_t *s) { int i; int nonzero = 0; memset(s, 0, MAX_POLY); for (i = 0; i < FORMAT_SYNDROMES; i++) { int j; s[i] = 0; for (j = 0; j < FORMAT_BITS; j++) if (u & (1 << j)) s[i] ^= gf16_exp[((i + 1) * j) % 15]; if (s[i]) nonzero = 1; } return nonzero; } static quirc_decode_error_t correct_format(uint16_t *f_ret) { uint16_t u = *f_ret; int i; uint8_t s[MAX_POLY]; uint8_t sigma[MAX_POLY]; /* Evaluate U (received codeword) at each of alpha_1 .. alpha_6 * to get S_1 .. S_6 (but we index them from 0). */ if (!format_syndromes(u, s)) return QUIRC_SUCCESS; berlekamp_massey(s, FORMAT_SYNDROMES, &gf16, sigma); /* Now, find the roots of the polynomial */ for (i = 0; i < 15; i++) if (!poly_eval(sigma, gf16_exp[15 - i], &gf16)) u ^= (1 << i); if (format_syndromes(u, s)) return QUIRC_ERROR_FORMAT_ECC; *f_ret = u; return QUIRC_SUCCESS; } /************************************************************************ * Decoder algorithm */ struct datastream { uint8_t raw[QUIRC_MAX_PAYLOAD]; int data_bits; int ptr; uint8_t data[QUIRC_MAX_PAYLOAD]; }; static inline int grid_bit(const struct quirc_code *code, int x, int y) { int p = y * code->size + x; return (code->cell_bitmap[p >> 3] >> (p & 7)) & 1; } static quirc_decode_error_t read_format(const struct quirc_code *code, struct quirc_data *data, int which) { int i; uint16_t format = 0; uint16_t fdata; quirc_decode_error_t err; if (which) { for (i = 0; i < 7; i++) format = (format << 1) | grid_bit(code, 8, code->size - 1 - i); for (i = 0; i < 8; i++) format = (format << 1) | grid_bit(code, code->size - 8 + i, 8); } else { static const int xs[15] = { 8, 8, 8, 8, 8, 8, 8, 8, 7, 5, 4, 3, 2, 1, 0 }; static const int ys[15] = { 0, 1, 2, 3, 4, 5, 7, 8, 8, 8, 8, 8, 8, 8, 8 }; for (i = 14; i >= 0; i--) format = (format << 1) | grid_bit(code, xs[i], ys[i]); } format ^= 0x5412; err = correct_format(&format); if (err) return err; fdata = format >> 10; data->ecc_level = fdata >> 3; data->mask = fdata & 7; return QUIRC_SUCCESS; } static int mask_bit(int mask, int i, int j) { switch (mask) { case 0: return !((i + j) % 2); case 1: return !(i % 2); case 2: return !(j % 3); case 3: return !((i + j) % 3); case 4: return !(((i / 2) + (j / 3)) % 2); case 5: return !((i * j) % 2 + (i * j) % 3); case 6: return !(((i * j) % 2 + (i * j) % 3) % 2); case 7: return !(((i * j) % 3 + (i + j) % 2) % 2); } return 0; } static int reserved_cell(int version, int i, int j) { const struct quirc_version_info *ver = &quirc_version_db[version]; int size = version * 4 + 17; int ai = -1, aj = -1, a; /* Finder + format: top left */ if (i < 9 && j < 9) return 1; /* Finder + format: bottom left */ if (i + 8 >= size && j < 9) return 1; /* Finder + format: top right */ if (i < 9 && j + 8 >= size) return 1; /* Exclude timing patterns */ if (i == 6 || j == 6) return 1; /* Exclude version info, if it exists. Version info sits adjacent to * the top-right and bottom-left finders in three rows, bounded by * the timing pattern. */ if (version >= 7) { if (i < 6 && j + 11 >= size) return 1; if (i + 11 >= size && j < 6) return 1; } /* Exclude alignment patterns */ for (a = 0; a < QUIRC_MAX_ALIGNMENT && ver->apat[a]; a++) { int p = ver->apat[a]; if (abs(p - i) < 3) ai = a; if (abs(p - j) < 3) aj = a; } if (ai >= 0 && aj >= 0) { a--; if (ai > 0 && ai < a) return 1; if (aj > 0 && aj < a) return 1; if (aj == a && ai == a) return 1; } return 0; } static void read_bit(const struct quirc_code *code, struct quirc_data *data, struct datastream *ds, int i, int j) { int bitpos = ds->data_bits & 7; int bytepos = ds->data_bits >> 3; int v = grid_bit(code, j, i); if (mask_bit(data->mask, i, j)) v ^= 1; if (v) ds->raw[bytepos] |= (0x80 >> bitpos); ds->data_bits++; } static void read_data(const struct quirc_code *code, struct quirc_data *data, struct datastream *ds) { int y = code->size - 1; int x = code->size - 1; int dir = -1; while (x > 0) { if (x == 6) x--; if (!reserved_cell(data->version, y, x)) read_bit(code, data, ds, y, x); if (!reserved_cell(data->version, y, x - 1)) read_bit(code, data, ds, y, x - 1); y += dir; if (y < 0 || y >= code->size) { dir = -dir; x -= 2; y += dir; } } } static quirc_decode_error_t codestream_ecc(struct quirc_data *data, struct datastream *ds) { const struct quirc_version_info *ver = &quirc_version_db[data->version]; const struct quirc_rs_params *sb_ecc = &ver->ecc[data->ecc_level]; struct quirc_rs_params lb_ecc; int bc = ver->data_bytes / sb_ecc->bs; int dst_offset = 0; int lb_count = ver->data_bytes - bc * sb_ecc->bs; int small_dw_total = bc * sb_ecc->dw; int i; memcpy(&lb_ecc, sb_ecc, sizeof(lb_ecc)); lb_ecc.dw++; lb_ecc.bs++; for (i = 0; i < bc; i++) { uint8_t *dst = ds->data + dst_offset; const struct quirc_rs_params *ecc = sb_ecc; quirc_decode_error_t err; int j = 0; int k; for (k = 0; k < sb_ecc->dw; k++) dst[j++] = ds->raw[k * bc + i]; if (i + lb_count >= bc) { dst[j++] = ds->raw[small_dw_total + i - lb_count]; ecc = &lb_ecc; } for (k = 0; k < sb_ecc->bs - sb_ecc->dw; k++) dst[j++] = ds->raw[small_dw_total + lb_count + i + k * bc]; err = correct_block(dst, ecc); if (err) return err; dst_offset += ecc->dw; } ds->data_bits = dst_offset * 8; return QUIRC_SUCCESS; } static inline int bits_remaining(const struct datastream *ds) { return ds->data_bits - ds->ptr; } static int take_bits(struct datastream *ds, int len) { int ret = 0; while (len && (ds->ptr < ds->data_bits)) { uint8_t b = ds->data[ds->ptr >> 3]; int bitpos = ds->ptr & 7; ret <<= 1; if ((b << bitpos) & 0x80) ret |= 1; ds->ptr++; len--; } return ret; } static int numeric_tuple(struct quirc_data *data, struct datastream *ds, int bits, int digits) { int tuple; int i; if (bits_remaining(ds) < bits) return -1; tuple = take_bits(ds, bits); for (i = digits - 1; i >= 0; i--) { data->payload[data->payload_len + i] = tuple % 10 + '0'; tuple /= 10; } data->payload_len += digits; return 0; } static quirc_decode_error_t decode_numeric(struct quirc_data *data, struct datastream *ds) { int bits = 14; int count; if (data->version < 10) bits = 10; else if (data->version < 27) bits = 12; count = take_bits(ds, bits); if (data->payload_len + count + 1 > QUIRC_MAX_PAYLOAD) return QUIRC_ERROR_DATA_OVERFLOW; while (count >= 3) { if (numeric_tuple(data, ds, 10, 3) < 0) return QUIRC_ERROR_DATA_UNDERFLOW; count -= 3; } if (count >= 2) { if (numeric_tuple(data, ds, 7, 2) < 0) return QUIRC_ERROR_DATA_UNDERFLOW; count -= 2; } if (count) { if (numeric_tuple(data, ds, 4, 1) < 0) return QUIRC_ERROR_DATA_UNDERFLOW; count--; } return QUIRC_SUCCESS; } static int alpha_tuple(struct quirc_data *data, struct datastream *ds, int bits, int digits) { int tuple; int i; if (bits_remaining(ds) < bits) return -1; tuple = take_bits(ds, bits); for (i = 0; i < digits; i++) { static const char *alpha_map = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"; data->payload[data->payload_len + digits - i - 1] = alpha_map[tuple % 45]; tuple /= 45; } data->payload_len += digits; return 0; } static quirc_decode_error_t decode_alpha(struct quirc_data *data, struct datastream *ds) { int bits = 13; int count; if (data->version < 7) bits = 9; else if (data->version < 11) bits = 10; count = take_bits(ds, bits); if (data->payload_len + count + 1 > QUIRC_MAX_PAYLOAD) return QUIRC_ERROR_DATA_OVERFLOW; while (count >= 2) { if (alpha_tuple(data, ds, 11, 2) < 0) return QUIRC_ERROR_DATA_UNDERFLOW; count -= 2; } if (count) { if (alpha_tuple(data, ds, 6, 1) < 0) return QUIRC_ERROR_DATA_UNDERFLOW; count--; } return QUIRC_SUCCESS; } static quirc_decode_error_t decode_byte(struct quirc_data *data, struct datastream *ds) { int bits = 16; int count; int i; if (data->version < 10) bits = 8; count = take_bits(ds, bits); if (data->payload_len + count + 1 > QUIRC_MAX_PAYLOAD) return QUIRC_ERROR_DATA_OVERFLOW; if (bits_remaining(ds) < count * 8) return QUIRC_ERROR_DATA_UNDERFLOW; for (i = 0; i < count; i++) data->payload[data->payload_len++] = take_bits(ds, 8); return QUIRC_SUCCESS; } static quirc_decode_error_t decode_kanji(struct quirc_data *data, struct datastream *ds) { int bits = 12; int count; int i; if (data->version < 10) bits = 8; else if (data->version < 27) bits = 10; count = take_bits(ds, bits); if (data->payload_len + count * 2 + 1 > QUIRC_MAX_PAYLOAD) return QUIRC_ERROR_DATA_OVERFLOW; if (bits_remaining(ds) < count * 13) return QUIRC_ERROR_DATA_UNDERFLOW; for (i = 0; i < count; i++) { int d = take_bits(ds, 13); uint16_t sjw; if (d + 0x8140 >= 0x9ffc) sjw = d + 0x8140; else sjw = d + 0xc140; data->payload[data->payload_len++] = sjw >> 8; data->payload[data->payload_len++] = sjw & 0xff; } return QUIRC_SUCCESS; } static quirc_decode_error_t decode_eci(struct quirc_data *data, struct datastream *ds) { if (bits_remaining(ds) < 8) return QUIRC_ERROR_DATA_UNDERFLOW; data->eci = take_bits(ds, 8); if ((data->eci & 0xc0) == 0x80) { if (bits_remaining(ds) < 8) return QUIRC_ERROR_DATA_UNDERFLOW; data->eci = (data->eci << 8) | take_bits(ds, 8); } else if ((data->eci & 0xe0) == 0xc0) { if (bits_remaining(ds) < 16) return QUIRC_ERROR_DATA_UNDERFLOW; data->eci = (data->eci << 16) | take_bits(ds, 16); } return QUIRC_SUCCESS; } static quirc_decode_error_t decode_payload(struct quirc_data *data, struct datastream *ds) { while (bits_remaining(ds) >= 4) { quirc_decode_error_t err = QUIRC_SUCCESS; int type = take_bits(ds, 4); switch (type) { case QUIRC_DATA_TYPE_NUMERIC: err = decode_numeric(data, ds); break; case QUIRC_DATA_TYPE_ALPHA: err = decode_alpha(data, ds); break; case QUIRC_DATA_TYPE_BYTE: err = decode_byte(data, ds); break; case QUIRC_DATA_TYPE_KANJI: err = decode_kanji(data, ds); break; case 7: err = decode_eci(data, ds); break; default: goto done; } if (err) return err; if (!(type & (type - 1)) && (type > data->data_type)) data->data_type = type; } done: /* Add nul terminator to all payloads */ if (data->payload_len >= sizeof(data->payload)) data->payload_len--; data->payload[data->payload_len] = 0; return QUIRC_SUCCESS; } quirc_decode_error_t quirc_decode(const struct quirc_code *code, struct quirc_data *data) { quirc_decode_error_t err; struct datastream ds; if ((code->size - 17) % 4) return QUIRC_ERROR_INVALID_GRID_SIZE; memset(data, 0, sizeof(*data)); memset(&ds, 0, sizeof(ds)); data->version = (code->size - 17) / 4; if (data->version < 1 || data->version > QUIRC_MAX_VERSION) return QUIRC_ERROR_INVALID_VERSION; /* Read format information -- try both locations */ err = read_format(code, data, 0); if (err) err = read_format(code, data, 1); if (err) return err; read_data(code, data, &ds); err = codestream_ecc(data, &ds); if (err) return err; err = decode_payload(data, &ds); if (err) return err; return QUIRC_SUCCESS; }