void sound_init( void )
{
/* Initialize FM chip */
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
/* YM2612 */
YM2612Init();
YM2612Config(config.dac_bits);
YM_Reset = YM2612ResetChip;
YM_Update = YM2612Update;
YM_Write = YM2612Write;
/* chip is running a VCLK / 144 = MCLK / 7 / 144 */
fm_cycles_ratio = 144 * 7;
}
else
{
/* YM2413 */
YM2413Init();
YM_Reset = YM2413ResetChip;
YM_Update = YM2413Update;
YM_Write = YM2413Write;
/* chip is running a ZCLK / 72 = MCLK / 15 / 72 */
fm_cycles_ratio = 72 * 15;
}
/* Initialize PSG chip */
SN76489_Config(0, config.psg_preamp, config.psgBoostNoise, 0xff);
}
void FM_Init(void)
{
switch(snd.fm_which)
{
case SND_EMU2413:
OPLL_init(snd.fm_clock, snd.sample_rate);
opll = OPLL_new();
OPLL_reset(opll);
OPLL_reset_patch(opll, 0);
break;
case SND_YM2413:
YM2413Init(1, snd.fm_clock, snd.sample_rate);
YM2413ResetChip(0);
break;
}
}
static void *ym2413_start(int sndindex, int clock, const void *config)
{
int rate = clock/72;
struct ym2413_info *info;
info = auto_malloc(sizeof(*info));
memset(info, 0, sizeof(*info));
/* emulator create */
info->chip = YM2413Init(clock, rate, sndindex);
if (!info->chip)
return NULL;
/* stream system initialize */
info->stream = stream_create(0,2,rate,info,ym2413_stream_update);
YM2413SetUpdateHandler(info->chip, _stream_update, info);
return info;
#if 0
int i, tst;
char name[40];
num = intf->num;
tst = YM3812_sh_start (msound);
if (tst)
return 1;
for (i=0;i<num;i++)
{
ym2413_reset (i);
ym2413[i].DAC_stream = stream_create(0, 1, clock/72, i, YM2413DAC_update);
if (ym2413[i].DAC_stream == -1)
return 1;
}
return 0;
#endif
}
/* Initialize sound chips emulation */
void sound_init(void)
{
/* Number of M-cycles executed per second. */
/* */
/* All emulated chips are kept in sync by using a common oscillator (MCLOCK) */
/* */
/* The original console would run exactly 53693175 M-cycles (53203424 for PAL), with */
/* 3420 M-cycles per line and 262 (313 for PAL) lines per frame, which gives an exact */
/* framerate of 59.92 (49.70 for PAL) fps. */
/* */
/* Since audio samples are generated at the end of the frame, to prevent audio skipping */
/* or lag between emulated frames, number of samples rendered per frame must be set to */
/* output samplerate (number of samples played per second) divided by output framerate */
/* (number of frames emulated per seconds). */
/* */
/* On some systems, we may want to achieve 100% smooth video rendering by synchronizing */
/* frame emulation with VSYNC, which frequency is generally not exactly those values. */
/* In that case, number of frames emulated per seconds is the same as the number of */
/* frames rendered per seconds by the host system video hardware. */
/* */
/* When no framerate is specified, base clock is original master clock value. */
/* Otherwise, it is based on the output framerate. */
/* */
double mclk = snd.frame_rate ? (MCYCLES_PER_LINE * lines_per_frame * snd.frame_rate) : system_clock;
/* For maximal accuracy, sound chips run in synchronization with 68k and Z80 cpus */
/* These values give the exact number of M-cycles executed per internal sample clock: */
/* . PSG chip runs at original rate and audio is resampled internally after each update */
/* . FM chips run by default (if HQ mode disabled) at the output rate directly */
/* We use 21.11 fixed point precision (max. mcycle value is 3420*313 i.e 21 bits max) */
psg_cycles_ratio = 16 * 15 * (1 << 11);
fm_cycles_ratio = (unsigned int)(mclk / (double) snd.sample_rate * 2048.0);
psg_cycles_count = 0;
fm_cycles_count = 0;
/* Initialize PSG core (input clock should be based on emulated system clock) */
SN76489_Init(mclk/15.0,snd.sample_rate);
/* Initialize FM cores (input clock and samplerate are only used when HQ mode is disabled) */
if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
/* YM2612 */
YM2612Init(mclk/7.0,snd.sample_rate);
YM_Reset = YM2612ResetChip;
YM_Update = YM2612Update;
YM_Write = YM2612Write;
/* In HQ mode, YM2612 is running at original rate (one sample each 144*7 M-cycles) */
/* Audio is resampled externally at the end of a frame. */
if (config.hq_fm)
{
fm_cycles_ratio = 144 * 7 * (1 << 11);
Fir_Resampler_time_ratio(mclk / (double)snd.sample_rate / (144.0 * 7.0), config.rolloff);
}
}
else
{
/* YM2413 */
YM2413Init(mclk/15.0,snd.sample_rate);
YM_Reset = YM2413ResetChip;
YM_Update = YM2413Update;
YM_Write = YM2413Write;
/* In HQ mode, YM2413 is running at original rate (one sample each 72*15 M-cycles) */
/* Audio is resampled externally at the end of a frame. */
if (config.hq_fm)
{
fm_cycles_ratio = 72 * 15 * (1 << 11);
Fir_Resampler_time_ratio(mclk / (double)snd.sample_rate / (72.0 * 15.0), config.rolloff);
}
}
#ifdef LOGSOUND
error("%f mcycles per second\n", mclk);
error("%d mcycles per PSG sample\n", psg_cycles_ratio);
error("%d mcycles per FM sample\n", fm_cycles_ratio);
#endif
}
