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sndhrdw
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warpwarp.c
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C/C++ Source or Header
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2000-04-04
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7KB
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237 lines
/****************************************************************************
*
* warpwarp.c
*
* sound driver
* juergen buchmueller <pullmoll@t-online.de>, jan 2000
*
****************************************************************************/
#include <math.h>
#include "driver.h"
#define CLOCK_16H (18432000/3/2/16)
#define CLOCK_1V (18432000/3/2/384)
static INT16 *decay = NULL;
static int channel;
static int sound_latch = 0;
static int music1_latch = 0;
static int music2_latch = 0;
static int sound_signal = 0;
static int sound_volume = 0;
static void *sound_volume_timer = NULL;
static int music_signal = 0;
static int music_volume = 0;
static void *music_volume_timer = NULL;
static int noise = 0;
static void sound_volume_decay(int param)
{
if( --sound_volume < 0 )
sound_volume = 0;
}
WRITE_HANDLER( warpwarp_sound_w )
{
stream_update(channel,0);
sound_latch = data;
sound_volume = 0x7fff; /* set sound_volume */
noise = 0x0000; /* reset noise shifter */
/* faster decay enabled? */
if( sound_latch & 8 )
{
/*
* R85(?) is 10k, Rb is 0, C92 is 1uF
* charge time t1 = 0.693 * (R24 + Rb) * C57 -> 0.22176s
* discharge time t2 = 0.693 * (Rb) * C57 -> 0
* C90(?) is only charged via D17 (1N914), no discharge!
* Decay:
* discharge C90(?) (1uF) through R13||R14 (22k||47k)
* 0.639 * 15k * 1uF -> 0.9585s
*/
if( sound_volume_timer )
timer_remove(sound_volume_timer);
sound_volume_timer = timer_pulse(TIME_IN_HZ(32768/0.9585), 0, sound_volume_decay);
}
else
{
/*
* discharge only after R93 (100k) and through the 10k
* potentiometerin the amplifier section.
* 0.639 * 110k * 1uF -> 7.0290s
* ...but this is not very realistic for the game sound :(
* maybe there _is_ a discharge through the diode D17?
*/
if( sound_volume_timer )
timer_remove(sound_volume_timer);
// sound_volume_timer = timer_pulse(TIME_IN_HZ(32768/7.0290), 0, sound_volume_decay);
sound_volume_timer = timer_pulse(TIME_IN_HZ(32768/1.917), 0, sound_volume_decay);
}
}
WRITE_HANDLER( warpwarp_music1_w )
{
stream_update(channel,0);
music1_latch = data & 63;
}
static void music_volume_decay(int param)
{
if( --music_volume < 0 )
music_volume = 0;
}
WRITE_HANDLER( warpwarp_music2_w )
{
stream_update(channel,0);
music2_latch = data;
music_volume = 0x7fff;
/* fast decay enabled? */
if( music2_latch & 16 )
{
/*
* Ra (R83?) is 10k, Rb is 0, C92 is 1uF
* charge time t1 = 0.693 * (Ra + Rb) * C -> 0.22176s
* discharge time is (nearly) zero, because Rb is zero
* C95(?) is only charged via D17, not discharged!
* Decay:
* discharge C95(?) (10uF) through R13||R14 (22k||47k)
* 0.639 * 15k * 10uF -> 9.585s
* ...I'm sure this is off by one number of magnitude :/
*/
if( music_volume_timer )
timer_remove(music_volume_timer);
// music_volume_timer = timer_pulse(TIME_IN_HZ(32768/9.585), 0, music_volume_decay);
music_volume_timer = timer_pulse(TIME_IN_HZ(32768/0.9585), 0, music_volume_decay);
}
else
{
/*
* discharge through R14 (47k),
* discharge C95(?) (10uF) through R14 (47k)
* 0.639 * 47k * 10uF -> 30.033s
*/
if( music_volume_timer )
timer_remove(music_volume_timer);
// music_volume_timer = timer_pulse(TIME_IN_HZ(32768/30.033), 0, music_volume_decay);
music_volume_timer = timer_pulse(TIME_IN_HZ(32768/3.0033), 0, music_volume_decay);
}
}
static void warpwarp_sound_update(int param, INT16 *buffer, int length)
{
static int vcarry = 0;
static int vcount = 0;
static int mcarry = 0;
static int mcount = 0;
while (length--)
{
*buffer++ = (sound_signal + music_signal) / 2;
/*
* The music signal is selected at a rate of 2H (1.536MHz) from the
* four bits of a 4 bit binary counter which is clocked with 16H,
* which is 192kHz, and is divided by 4 times (64 - music1_latch).
* 0 = 256 steps -> 750 Hz
* 1 = 252 steps -> 761.9 Hz
* ...
* 32 = 128 steps -> 1500 Hz
* ...
* 48 = 64 steps -> 3000 Hz
* ...
* 63 = 4 steps -> 48 kHz
*/
mcarry -= CLOCK_16H / (4 * (64 - music1_latch));
while( mcarry < 0 )
{
mcarry += Machine->sample_rate;
mcount++;
music_signal = (mcount & ~music2_latch & 15) ? decay[music_volume] : 0;
/* override by noise gate? */
if( (music2_latch & 32) && (noise & 0x8000) )
music_signal = decay[music_volume];
}
/* clock 1V = 8kHz */
vcarry -= CLOCK_1V;
while (vcarry < 0)
{
vcarry += Machine->sample_rate;
vcount++;
/* noise is clocked with raising edge of 2V */
if ((vcount & 3) == 2)
{
/* bit0 = bit0 ^ !bit10 */
if ((noise & 1) == ((noise >> 10) & 1))
noise = (noise << 1) | 1;
else
noise = noise << 1;
}
switch (sound_latch & 7)
{
case 0: /* 4V */
sound_signal = (vcount & 0x04) ? decay[sound_volume] : 0;
break;
case 1: /* 8V */
sound_signal = (vcount & 0x08) ? decay[sound_volume] : 0;
break;
case 2: /* 16V */
sound_signal = (vcount & 0x10) ? decay[sound_volume] : 0;
break;
case 3: /* 32V */
sound_signal = (vcount & 0x20) ? decay[sound_volume] : 0;
break;
case 4: /* TONE1 */
sound_signal = !(vcount & 0x01) && !(vcount & 0x10) ? decay[sound_volume] : 0;
break;
case 5: /* TONE2 */
sound_signal = !(vcount & 0x02) && !(vcount & 0x20) ? decay[sound_volume] : 0;
break;
case 6: /* TONE3 */
sound_signal = !(vcount & 0x04) && !(vcount & 0x40) ? decay[sound_volume] : 0;
break;
default: /* NOISE */
/* QH of 74164 #4V */
sound_signal = (noise & 0x8000) ? decay[sound_volume] : 0;
}
}
}
}
int warpwarp_sh_start(const struct MachineSound *msound)
{
int i;
decay = (INT16 *) malloc(32768 * sizeof(INT16));
if( !decay )
return 1;
for( i = 0; i < 0x8000; i++ )
decay[0x7fff-i] = (INT16) (0x7fff/exp(1.0*i/4096));
channel = stream_init("WarpWarp", 100, Machine->sample_rate, 0, warpwarp_sound_update);
return 0;
}
void warpwarp_sh_stop(void)
{
if( decay )
free(decay);
decay = NULL;
music_volume_timer = NULL;
sound_volume_timer = NULL;
}
void warpwarp_sh_update(void)
{
stream_update(channel,0);
}