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SID: Don't uselessly upconvert from 16bpp mono to 28bpp stereo

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cRSID natively renders its output as a 16bit mono stream.  There's no
reason to not use it as-is, and save a bunch of CPU cycles in the
process.

Change-Id: Ib934c05e77298e377053b29db91d1f05fb65eb76
This commit is contained in:
Solomon Peachy 2025-09-02 20:19:22 -04:00
parent 6f7dbc2153
commit 695698b918
1 changed files with 9 additions and 11 deletions
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20
lib/rbcodec/codecs/sid.c
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@ -34,17 +34,15 @@ CODEC_HEADER
#define SID_BUFFER_SIZE 0x10000
#define SAMPLE_RATE 44100
static int32_t samples_r[CHUNK_SIZE] IBSS_ATTR;
static int32_t samples_l[CHUNK_SIZE] IBSS_ATTR;
static int16_t samples[CHUNK_SIZE] IBSS_ATTR;
void sid_render(int32_t *buffer_r, int32_t *buffer_l, unsigned long len) ICODE_ATTR;
void sid_render(int32_t *buffer_r, int32_t *buffer_l, unsigned long len) {
static void sid_render(int16_t *buffer, unsigned long len) ICODE_ATTR;
static void sid_render(int16_t *buffer, unsigned long len) {
unsigned long bp;
int output;
for (bp = 0; bp < len; bp++) {
output = cRSID_generateSample(&cRSID_C64) << 12;
*(buffer_r + bp) = output; *(buffer_l + bp) = output;
buffer[bp] = cRSID_generateSample(&cRSID_C64);
}
}
@ -52,8 +50,8 @@ enum codec_status codec_main(enum codec_entry_call_reason reason)
{
if (reason == CODEC_LOAD) {
ci->configure(DSP_SET_FREQUENCY, SAMPLE_RATE);
ci->configure(DSP_SET_SAMPLE_DEPTH, 28);
ci->configure(DSP_SET_STEREO_MODE, STEREO_NONINTERLEAVED);
ci->configure(DSP_SET_SAMPLE_DEPTH, 16);
ci->configure(DSP_SET_STEREO_MODE, STEREO_MONO);
cRSID_init(SAMPLE_RATE, CHUNK_SIZE);
}
@ -105,8 +103,8 @@ enum codec_status codec_run(void)
cRSID_initSIDtune(&cRSID_C64, SIDheader, subSong + 1);
}
sid_render(samples_r, samples_l, CHUNK_SIZE);
ci->pcmbuf_insert(samples_r, samples_l, CHUNK_SIZE);
sid_render(samples, CHUNK_SIZE);
ci->pcmbuf_insert(samples, NULL, CHUNK_SIZE);
/* New time is in param */
action = ci->get_command(&param);