/** Documented at declaration */
int
gpujpeg_table_huffman_decoder_init(struct gpujpeg_table_huffman_decoder* table, struct gpujpeg_table_huffman_decoder* d_table, enum gpujpeg_component_type comp_type, enum gpujpeg_huffman_type huff_type)
{
assert(comp_type == GPUJPEG_COMPONENT_LUMINANCE || comp_type == GPUJPEG_COMPONENT_CHROMINANCE);
assert(huff_type == GPUJPEG_HUFFMAN_DC || huff_type == GPUJPEG_HUFFMAN_AC);
if ( comp_type == GPUJPEG_COMPONENT_LUMINANCE ) {
if ( huff_type == GPUJPEG_HUFFMAN_DC ) {
memcpy(table->bits, gpujpeg_table_huffman_y_dc_bits, sizeof(table->bits));
memcpy(table->huffval, gpujpeg_table_huffman_y_dc_value, sizeof(table->huffval));
} else {
memcpy(table->bits, gpujpeg_table_huffman_y_ac_bits, sizeof(table->bits));
memcpy(table->huffval, gpujpeg_table_huffman_y_ac_value, sizeof(table->huffval));
}
} else if ( comp_type == GPUJPEG_COMPONENT_CHROMINANCE ) {
if ( huff_type == GPUJPEG_HUFFMAN_DC ) {
memcpy(table->bits, gpujpeg_table_huffman_cbcr_dc_bits, sizeof(table->bits));
memcpy(table->huffval, gpujpeg_table_huffman_cbcr_dc_value, sizeof(table->huffval));
} else {
memcpy(table->bits, gpujpeg_table_huffman_cbcr_ac_bits, sizeof(table->bits));
memcpy(table->huffval, gpujpeg_table_huffman_cbcr_ac_value, sizeof(table->huffval));
}
}
gpujpeg_table_huffman_decoder_compute(table, d_table);
return 0;
}
/**
* Read huffman table definition block from image
*
* @param decoder
* @param image
* @return 0 if succeeds, otherwise nonzero
*/
int
gpujpeg_reader_read_dht(struct gpujpeg_decoder* decoder, uint8_t** image)
{
int length = (int)gpujpeg_reader_read_2byte(*image);
length -= 2;
int index = gpujpeg_reader_read_byte(*image);
struct gpujpeg_table_huffman_decoder* table = NULL;
struct gpujpeg_table_huffman_decoder* d_table = NULL;
switch(index) {
case 0:
table = &decoder->table_huffman[GPUJPEG_COMPONENT_LUMINANCE][GPUJPEG_HUFFMAN_DC];
d_table = decoder->d_table_huffman[GPUJPEG_COMPONENT_LUMINANCE][GPUJPEG_HUFFMAN_DC];
break;
case 16:
table = &decoder->table_huffman[GPUJPEG_COMPONENT_LUMINANCE][GPUJPEG_HUFFMAN_AC];
d_table = decoder->d_table_huffman[GPUJPEG_COMPONENT_LUMINANCE][GPUJPEG_HUFFMAN_AC];
break;
case 1:
table = &decoder->table_huffman[GPUJPEG_COMPONENT_CHROMINANCE][GPUJPEG_HUFFMAN_DC];
d_table = decoder->d_table_huffman[GPUJPEG_COMPONENT_CHROMINANCE][GPUJPEG_HUFFMAN_DC];
break;
case 17:
table = &decoder->table_huffman[GPUJPEG_COMPONENT_CHROMINANCE][GPUJPEG_HUFFMAN_AC];
d_table = decoder->d_table_huffman[GPUJPEG_COMPONENT_CHROMINANCE][GPUJPEG_HUFFMAN_AC];
break;
default:
fprintf(stderr, "[GPUJPEG] [Error] DHT marker index should be 0, 1, 16 or 17 but %d was presented!\n", index);
return -1;
}
length -= 1;
// Read in bits[]
table->bits[0] = 0;
int count = 0;
for ( int i = 1; i <= 16; i++ ) {
table->bits[i] = gpujpeg_reader_read_byte(*image);
count += table->bits[i];
if ( length > 0 ) {
length--;
} else {
fprintf(stderr, "[GPUJPEG] [Error] DHT marker unexpected end when reading bit counts!\n", index);
return -1;
}
}
// Read in huffval
for ( int i = 0; i < count; i++ ){
table->huffval[i] = gpujpeg_reader_read_byte(*image);
if ( length > 0 ) {
length--;
} else {
fprintf(stderr, "[GPUJPEG] [Error] DHT marker unexpected end when reading huffman values!\n", index);
return -1;
}
}
// Check length
if ( length > 0 ) {
fprintf(stderr, "[GPUJPEG] [Warning] DHT marker contains %d more bytes than needed!\n", length);
*image += length;
}
// Compute huffman table for read values
gpujpeg_table_huffman_decoder_compute(table, d_table);
return 0;
}
