vgmstream/src/coding/circus_decoder.c

30 lines
969 B
C

#include "coding.h"
/* Circus XPCM mode 2 decoding, verified vs EF.exe (info from foo_adpcm/libpcm and https://github.com/lioncash/ExtractData) */
void decode_circus_adpcm(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do) {
int i, sample_pos = 0;
int32_t hist = stream->adpcm_history1_32;
int scale = stream->adpcm_scale;
off_t frame_offset = stream->offset; /* frame size is 1 */
for (i = first_sample; i < first_sample + samples_to_do; i++) {
int8_t code = read_8bit(frame_offset+i,stream->streamfile);
hist += code << scale;
if (code == 0) {
if (scale > 0)
scale--;
}
else if (code == 127 || code == -128) {
if (scale < 8)
scale++;
}
outbuf[sample_pos] = hist;
}
stream->adpcm_history1_32 = hist;
stream->adpcm_scale = scale;
}