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quirc/lib/decode.c
Daniel Beer 42c79481e7 decode: support multiple data segments. 
Previously, the payload was assumed to consist of one large data
segment. Now, multiple segments of different types may be concatenated
together. The data type reported is the highest data type encountered
while decoding.
2013-05-29 10:26:13 +12:00

884 lines
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/* quirc -- QR-code recognition library
* Copyright (C) 2010-2012 Daniel Beer <dlbeer@gmail.com>
*
* 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 <string.h>
#include <stdlib.h>
#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_mult(uint8_t *r, const uint8_t *a, const uint8_t *b,
const struct galois_field *gf)
{
int i;
memset(r, 0, MAX_POLY);
for (i = 0; i < MAX_POLY; i++) {
int j;
for (j = 0; j + i < MAX_POLY; j++) {
uint8_t ca = a[i];
uint8_t cb = b[j];
if (!(ca && cb))
continue;
r[i + j] ^= gf->exp[(gf->log[ca] +
gf->log[cb]) %
gf->p];
}
}
}
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 + 1) * j) % 255];
}
if (s[i])
nonzero = 1;
}
return nonzero;
}
static quirc_decode_error_t correct_block(uint8_t *data, const struct quirc_rs_params *ecc)
{
int npar = ecc->ce;
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 */
poly_mult(omega, sigma, s, &gf256);
memset(omega + npar, 0, MAX_POLY - npar);
/* 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_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;
default:
goto done;
}
if (err)
return err;
if (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;
}
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