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audio: improve cycle accuracy of SN76496+YM2612

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This commit is contained in:
kub 2020-04-22 20:41:51 +02:00
parent 6432fb18ba
commit 09b96f9940
4 changed files with 32 additions and 56 deletions
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67
pico/sound/sound.c
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@ -19,9 +19,6 @@ void (*PsndMix_32_to_16l)(short *dest, int *src, int count) = mix_32_to_16l_ster
// master int buffer to mix to
static int PsndBuffer[2*(44100+100)/50];
// dac, psg
static unsigned short dac_info[312+4]; // pos in sample buffer
// cdda output buffer
short cdda_out_buffer[2*1152];
@ -29,23 +26,6 @@ short cdda_out_buffer[2*1152];
extern int *sn76496_regs;
static void dac_recalculate(void)
{
int lines = Pico.m.pal ? 313 : 262;
int i, pos;
pos = 0; // Q16
for(i = 0; i <= lines; i++)
{
dac_info[i] = ((pos+0x8000) >> 16); // round to nearest
pos += Pico.snd.fm_mult;
}
for (i = lines+1; i < sizeof(dac_info) / sizeof(dac_info[0]); i++)
dac_info[i] = dac_info[i-1];
}
PICO_INTERNAL void PsndReset(void)
{
// PsndRerate calls YM2612Init, which also resets
@ -88,12 +68,9 @@ void PsndRerate(int preserve_state)
Pico.snd.len_e_cnt = 0; // Q16
// samples per line (Q16)
Pico.snd.fm_mult = 65536LL * PicoIn.sndRate / (target_fps*target_lines);
Pico.snd.smpl_mult = 65536LL * PicoIn.sndRate / (target_fps*target_lines);
// samples per z80 clock (Q20)
Pico.snd.dac_mult = 16 * Pico.snd.fm_mult * 15/7 / 488;
// recalculate dac info
dac_recalculate();
Pico.snd.clkl_mult = 16 * Pico.snd.smpl_mult * 15/7 / 488;
// clear all buffers
memset32(PsndBuffer, 0, sizeof(PsndBuffer)/4);
@ -118,8 +95,6 @@ PICO_INTERNAL void PsndStartFrame(void)
Pico.snd.len_e_cnt -= 0x10000;
Pico.snd.len_use++;
}
Pico.snd.psg_line = 0;
}
PICO_INTERNAL void PsndDoDAC(int cyc_to)
@ -128,7 +103,7 @@ PICO_INTERNAL void PsndDoDAC(int cyc_to)
int dout = ym2612.dacout;
// number of samples to fill in buffer (Q20)
len = (cyc_to * Pico.snd.dac_mult) - Pico.snd.dac_pos;
len = (cyc_to * Pico.snd.clkl_mult) - Pico.snd.dac_pos;
// update position and calculate buffer offset and length
pos = (Pico.snd.dac_pos+0x80000) >> 20;
@ -163,17 +138,18 @@ PICO_INTERNAL void PsndDoDAC(int cyc_to)
PICO_INTERNAL void PsndDoPSG(int line_to)
{
int line_from = Pico.snd.psg_line;
int pos, pos1, len;
int pos, len;
int stereo = 0;
pos = dac_info[line_from];
pos1 = dac_info[line_to + 1];
len = pos1 - pos;
// Q16, number of samples since last call
len = ((line_to+1) * Pico.snd.smpl_mult) - Pico.snd.psg_pos;
if (len <= 0)
return;
Pico.snd.psg_line = line_to + 1;
// update position and calculate buffer offset and length
pos = (Pico.snd.psg_pos+0x8000) >> 16;
Pico.snd.psg_pos += len;
len = ((Pico.snd.psg_pos+0x8000) >> 16) - pos;
if (!PicoIn.sndOut || !(PicoIn.opt & POPT_EN_PSG))
return;
@ -185,22 +161,22 @@ PICO_INTERNAL void PsndDoPSG(int line_to)
SN76496Update(PicoIn.sndOut + pos, len, stereo);
}
PICO_INTERNAL void PsndDoFM(int line_to)
PICO_INTERNAL void PsndDoFM(int cyc_to)
{
int pos, len;
int stereo = 0;
// Q16, number of samples since last call
len = ((line_to-1) * Pico.snd.fm_mult) - Pico.snd.fm_pos;
len = (cyc_to * Pico.snd.clkl_mult) - Pico.snd.fm_pos;
// don't do this too often (about every 4th scanline)
if (len >> 16 <= PicoIn.sndRate >> 12)
if (len >> 20 <= PicoIn.sndRate >> 12)
return;
// update position and calculate buffer offset and length
pos = (Pico.snd.fm_pos+0x8000) >> 16;
pos = (Pico.snd.fm_pos+0x80000) >> 20;
Pico.snd.fm_pos += len;
len = ((Pico.snd.fm_pos+0x8000) >> 16) - pos;
len = ((Pico.snd.fm_pos+0x80000) >> 20) - pos;
// fill buffer
if (PicoIn.opt & POPT_EN_STEREO) {
@ -273,7 +249,7 @@ PICO_INTERNAL void PsndClear(void)
if (!(PicoIn.opt & POPT_EN_FM))
memset32(PsndBuffer, 0, PicoIn.opt & POPT_EN_STEREO ? len*2 : len);
// drop pos remainder to avoid rounding errors (not entirely correct though)
Pico.snd.dac_pos = Pico.snd.fm_pos = 0;
Pico.snd.dac_pos = Pico.snd.fm_pos = Pico.snd.psg_pos = 0;
}
@ -281,7 +257,7 @@ static int PsndRender(int offset, int length)
{
int *buf32;
int stereo = (PicoIn.opt & 8) >> 3;
int fmlen = ((Pico.snd.fm_pos+0x8000) >> 16);
int fmlen = ((Pico.snd.fm_pos+0x80000) >> 20);
int daclen = ((Pico.snd.dac_pos+0x80000) >> 20);
buf32 = PsndBuffer+(offset<<stereo);
@ -297,16 +273,19 @@ static int PsndRender(int offset, int length)
if (length-daclen > 0) {
short *dacbuf = PicoIn.sndOut + (daclen << stereo);
Pico.snd.dac_pos += (length-daclen) << 20;
for (; length-daclen > 0; daclen++) {
*dacbuf++ += Pico.snd.dac_val2;
if (stereo) dacbuf++;
for (daclen++; length-daclen > 0; daclen++) {
*dacbuf++ += Pico.snd.dac_val;
if (stereo) dacbuf++;
}
Pico.snd.dac_val2 = Pico.snd.dac_val;
}
// Add in parts of the FM buffer not yet done
if (length-fmlen > 0) {
int *fmbuf = buf32 + ((fmlen-offset) << stereo);
Pico.snd.fm_pos += (length-fmlen) << 16;
Pico.snd.fm_pos += (length-fmlen) << 20;
if (PicoIn.opt & POPT_EN_FM)
YM2612UpdateOne(fmbuf, length-fmlen, stereo, 1);
}
@ -344,8 +323,6 @@ PICO_INTERNAL void PsndGetSamples(int y)
{
static int curr_pos = 0;
if (ym2612.dacen)
PsndDoDAC(cycles_68k_to_z80(Pico.t.m68c_aim - Pico.t.m68c_frame_start));
PsndDoPSG(y - 1);
curr_pos = PsndRender(0, Pico.snd.len_use);