/**
*
* Decode a single block that contains the DCT coefficients.
* The table coefficients is already dezigzaged at the end of the operation.
*
*/
static void process_Huffman_data_unit(struct jdec_private *priv, int component)
{
unsigned char j;
unsigned int huff_code;
unsigned char size_val, count_0;
struct component *c = &priv->component_infos[component];
short int DCT[64];
/* Initialize the DCT coef table */
memset(DCT, 0, sizeof(DCT));
/* DC coefficient decoding */
huff_code = get_next_huffman_code(priv, c->DC_table);
//trace("+ %x\n", huff_code);
if (huff_code) {
get_nbits(priv->reservoir, priv->nbits_in_reservoir, priv->stream, huff_code, DCT[0]);
DCT[0] += c->previous_DC;
c->previous_DC = DCT[0];
} else {
DCT[0] = c->previous_DC;
}
/* AC coefficient decoding */
j = 1;
while (j<64)
{
huff_code = get_next_huffman_code(priv, c->AC_table);
//trace("- %x\n", huff_code);
size_val = huff_code & 0xF;
count_0 = huff_code >> 4;
if (size_val == 0)
{ /* RLE */
if (count_0 == 0)
break; /* EOB found, go out */
else if (count_0 == 0xF)
j += 16; /* skip 16 zeros */
}
else
{
j += count_0; /* skip count_0 zeroes */
if (__unlikely(j >= 64))
{
//snprintf(error_string, sizeof(error_string), "Bad huffman data (buffer overflow)");
break;
}
get_nbits(priv->reservoir, priv->nbits_in_reservoir, priv->stream, size_val, DCT[j]);
j++;
}
}
for (j = 0; j < 64; j++)
c->DCT[j] = DCT[zigzag[j]];
}
/**
*
* Decode a single block that contains the DCT coefficients.
* The table coefficients is already dezigzaged at the end of the operation.
*
*/
static int process_Huffman_data_unit(struct huffman_context *hc, struct jdec_task *hdata, int component, short int *DCT_out)
{
unsigned char j;
unsigned int huff_code;
int retcode;
unsigned char size_val, count_0;
struct component *c = &hc->component_infos[component];
short int DCT[64];
/* Initialize the DCT coef table */
memset(DCT, 0, sizeof(DCT));
/* DC coefficient decoding */
retcode = get_next_huffman_code(hdata, c->DC_table);
// End of stream
if(retcode == -1)
return -1;
else
huff_code = (unsigned int)retcode;
if (huff_code) {
get_nbits(hdata->reservoir, hdata->nbits_in_reservoir, hdata->stream, huff_code, DCT[0]);
DCT[0] += c->previous_DC;
c->previous_DC = DCT[0];
} else {
DCT[0] = c->previous_DC;
}
/* AC coefficient decoding */
j = 1;
while (j<64)
{
huff_code = get_next_huffman_code(hdata, c->AC_table);
//trace("- %x\n", huff_code);
size_val = huff_code & 0xF;
count_0 = huff_code >> 4;
if (size_val == 0)
{ /* RLE */
if (count_0 == 0)
break; /* EOB found, go out */
else if (count_0 == 0xF)
j += 16; /* skip 16 zeros */
}
else
{
j += count_0; /* skip count_0 zeroes */
if (j >= 64)
{
snprintf(error_string, sizeof(error_string), "Bad huffman data (buffer overflow)");
break;
}
get_nbits(hdata->reservoir, hdata->nbits_in_reservoir, hdata->stream, size_val, DCT[j]);
j++;
}
}
for (j = 0; j < 64; j++)
DCT_out[j] = DCT[zigzag[j]];
return 0;
}