/* End of frame update, return the number of samples run so far. */
int sound_update(unsigned int cycles)
{
int size, avail;
/* run PSG & FM chips until end of frame */
cycles <<= 11;
psg_update(cycles);
fm_update(cycles);
/* check number of available FM samples */
if (config.hq_fm)
{
size = Fir_Resampler_avail();
}
else
{
size = (snd.fm.pos - snd.fm.buffer) >> 1;
}
#ifdef LOGSOUND
error("%d FM samples available\n",size);
#endif
/* check number of available PSG samples */
avail = snd.psg.pos - snd.psg.buffer;
#ifdef LOGSOUND
error("%d PSG samples available\n", avail);
#endif
/* resynchronize FM & PSG chips */
if (size > avail)
{
/* FM chip is ahead */
fm_cycles_count += SN76489_Clocks(size - avail) * psg_cycles_ratio;
/* return number of available samples */
size = avail;
}
else
{
/* PSG chip is ahead */
psg_cycles_count += SN76489_Clocks(avail - size) * psg_cycles_ratio;
}
#ifdef LOGSOUND
error("%lu PSG cycles run\n",psg_cycles_count);
error("%lu FM cycles run \n",fm_cycles_count);
#endif
/* adjust PSG & FM cycle counts for next frame */
psg_cycles_count -= cycles;
fm_cycles_count -= cycles;
#ifdef LOGSOUND
error("%lu PSG cycles left\n",psg_cycles_count);
error("%lu FM cycles left\n",fm_cycles_count);
#endif
return size;
}
void psg_write(unsigned int clocks, unsigned int data)
{
int index;
/* PSG chip synchronization */
if (clocks > psg.clocks)
{
/* run PSG chip until current timestamp */
psg_update(clocks);
/* update internal M-cycles clock counter */
psg.clocks += ((clocks - psg.clocks + PSG_MCYCLES_RATIO - 1) / PSG_MCYCLES_RATIO) * PSG_MCYCLES_RATIO;
}
if (data & 0x80)
{
/* latch register index (1xxx----) */
psg.latch = index = (data >> 4) & 0x07;
}
/* Write PSG chip */
void psg_write(unsigned int cycles, unsigned int data)
{
psg_update(cycles << 11);
SN76489_Write(data);
}