vgmstream/src/coding/nds_procyon_decoder.c
2008-12-28 06:29:43 +00:00

61 lines
1.7 KiB
C

#include "coding.h"
#include "../util.h"
/* ADPCM found in NDS games using Procyon Studio Digital Sound Elements */
static const int8_t proc_coef[5][2] =
{
{0x00,0x00},
{0x3C,0x00},
{0x73,0xCC},
{0x62,0xC9},
{0x7A,0xC4},
};
void decode_nds_procyon(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do) {
int i=first_sample;
int32_t sample_count;
int framesin = first_sample/30;
uint8_t header = read_8bit(framesin*16+15+stream->offset,stream->streamfile) ^ 0x80;
int scale = 12 - (header & 0xf);
int coef_index = (header >> 4) & 0xf;
int32_t hist1 = stream->adpcm_history1_32;
int32_t hist2 = stream->adpcm_history2_32;
int32_t coef1;
int32_t coef2;
if (coef_index > 4) coef_index = 0;
coef1 = proc_coef[coef_index][0];
coef2 = proc_coef[coef_index][1];
first_sample = first_sample%30;
for (i=first_sample,sample_count=0; i<first_sample+samples_to_do; i++,sample_count+=channelspacing) {
int sample_byte = read_8bit(framesin*16+stream->offset+i/2,stream->streamfile) ^ 0x80;
int32_t sample =
(int32_t)
(i&1?
get_high_nibble_signed(sample_byte):
get_low_nibble_signed(sample_byte)
) * 64 * 64;
if (scale < 0)
{
sample <<= -scale;
}
else
sample >>= scale;
sample = (hist1 * coef1 + hist2 * coef2 + 32) / 64 + (sample * 64);
hist2 = hist1;
hist1 = sample;
outbuf[sample_count] = clamp16((sample + 32) / 64) / 64 * 64;
}
stream->adpcm_history1_32 = hist1;
stream->adpcm_history2_32 = hist2;
}