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Fix decoding of numeric and alphanumeric data types.

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If the number of characters in the stream isn't a multiple of the full
tuple size, the remaining characters are encoded in a special short
tuple.
This commit is contained in:
Daniel Beer 2013-05-14 09:25:05 +12:00
parent 8d0eb68255
commit 0335fabf97
1 changed files with 71 additions and 36 deletions
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103
lib/decode.c
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@ -609,7 +609,7 @@ static quirc_decode_error_t codestream_ecc(struct quirc_data *data,
return QUIRC_SUCCESS;
}
static int get_bits(uint8_t *data, int pos, int len)
static int get_bits(const uint8_t *data, int pos, int len)
{
int ret = 0;
@ -627,13 +627,33 @@ static int get_bits(uint8_t *data, int pos, int len)
return ret;
}
static int numeric_tuple(struct quirc_data *data,
const struct datastream *ds,
int *ptr, int bits, int digits)
{
int tuple;
int i;
if (*ptr + bits > ds->data_bits)
return -1;
tuple = get_bits(ds->data, *ptr, bits);
*ptr += bits;
for (i = 0; i < digits; i++) {
data->payload[data->payload_len++] = tuple % 10 + '0';
tuple /= 10;
}
return 0;
}
static quirc_decode_error_t decode_numeric(struct quirc_data *data,
struct datastream *ds)
{
int bits = 14;
int count;
int tuples;
int i;
int ptr;
if (data->version < 10)
bits = 10;
@ -644,36 +664,57 @@ static quirc_decode_error_t decode_numeric(struct quirc_data *data,
if (count + 1 > QUIRC_MAX_PAYLOAD)
return QUIRC_ERROR_DATA_OVERFLOW;
tuples = (count + 2) / 3;
if (tuples * 10 + bits + 4 > ds->data_bits)
data->payload_len = 0;
ptr = bits + 4;
while (data->payload_len + 2 < count)
if (numeric_tuple(data, ds, &ptr, 10, 3) < 0)
return QUIRC_ERROR_DATA_UNDERFLOW;
for (i = 0; i < tuples; i++) {
int d = get_bits(ds->data, i * 10 + bits + 4, 10);
int p = i * 3 + 2;
int j;
if ((data->payload_len + 1 < count) &&
(numeric_tuple(data, ds, &ptr, 7, 2) < 0))
return QUIRC_ERROR_DATA_UNDERFLOW;
for (j = 0; j < 3; j++) {
if (p < count)
data->payload[p] = d % 10 + '0';
d /= 10;
p--;
}
}
if ((data->payload_len < count) &&
(numeric_tuple(data, ds, &ptr, 4, 1) < 0))
return QUIRC_ERROR_DATA_UNDERFLOW;
data->payload[count] = 0;
data->payload_len = count;
return QUIRC_SUCCESS;
}
static int alpha_tuple(struct quirc_data *data,
const struct datastream *ds,
int *ptr, int bits, int digits)
{
int tuple;
int i;
if (*ptr + bits > ds->data_bits)
return -1;
tuple = get_bits(ds->data, *ptr, bits);
*ptr += 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;
int tuples;
int i;
int ptr;
if (data->version < 7)
bits = 9;
@ -684,24 +725,18 @@ static quirc_decode_error_t decode_alpha(struct quirc_data *data,
if (count + 1 > QUIRC_MAX_PAYLOAD)
return QUIRC_ERROR_DATA_OVERFLOW;
tuples = (count + 1) / 2;
if (tuples * 11 + bits + 4 > ds->data_bits)
data->payload_len = 0;
ptr = bits + 4;
while (data->payload_len + 1 < count)
if (alpha_tuple(data, ds, &ptr, 11, 2) < 0)
return QUIRC_ERROR_DATA_UNDERFLOW;
for (i = 0; i < tuples; i++) {
static const char *alpha_map =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
int d = get_bits(ds->data, i * 11 + bits + 4, 11);
int p = i * 2;
if (p + 1 < count)
data->payload[p + 1] = alpha_map[d % 45];
data->payload[p] = alpha_map[(d / 45) % 45];
}
if ((data->payload_len < count) &&
(alpha_tuple(data, ds, &ptr, 6, 1) < 0))
return QUIRC_ERROR_DATA_UNDERFLOW;
data->payload[count] = 0;
data->payload_len = count;
return QUIRC_SUCCESS;
}