home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
AmigActive 10
/
AACD 10.iso
/
AACD
/
Games
/
MAME
/
src
/
sndhrdw
/
redbaron.c
< prev
next >
Wrap
C/C++ Source or Header
|
2000-04-04
|
5KB
|
224 lines
/*
Red Baron sound notes:
bit function
7-4 explosion volume
3 start led
2 shot (machine gun sound)
1 squeal (nosedive sound)
0 POTSEL (rb_input_select)
*/
#include <math.h>
#include "driver.h"
/* used in drivers/redbaron.c to select joystick pot */
extern int rb_input_select;
/* Statics */
static INT16 *vol_lookup = NULL;
static INT16 vol_crash[16];
static int channel;
static int latch;
static int poly_counter;
static int poly_shift;
static int filter_counter;
static int crash_amp;
static int shot_amp;
static int shot_amp_counter;
static int squeal_amp;
static int squeal_amp_counter;
static int squeal_off_counter;
static int squeal_on_counter;
static int squeal_out;
WRITE_HANDLER( redbaron_sounds_w )
{
/* If sound is off, don't bother playing samples */
if( data == latch )
return;
stream_update(channel, 0);
latch = data;
rb_input_select = data & 1;
}
WRITE_HANDLER( redbaron_pokey_w )
{
if( latch & 0x20 )
pokey1_w (offset, data);
}
static void redbaron_sound_update(int param, INT16 *buffer, int length)
{
while( length-- )
{
int sum = 0;
/* polynome shifter E5 and F4 (LS164) clocked with 12kHz */
poly_counter -= 12000;
while( poly_counter <= 0 )
{
poly_counter += Machine->sample_rate;
if( ((poly_shift & 0x0001) == 0) == ((poly_shift & 0x4000) == 0) )
poly_shift = (poly_shift << 1) | 1;
else
poly_shift <<= 1;
}
/* What is the exact low pass filter frequency? */
filter_counter -= 330;
while( filter_counter <= 0 )
{
filter_counter += Machine->sample_rate;
crash_amp = (poly_shift & 1) ? latch >> 4 : 0;
}
/* mix crash sound at 35% */
sum += vol_crash[crash_amp] * 35 / 100;
/* shot not active: charge C32 (0.1u) */
if( (latch & 0x04) == 0 )
shot_amp = 32767;
else
if( (poly_shift & 0x8000) == 0 )
{
if( shot_amp > 0 )
{
/* discharge C32 (0.1u) through R26 (33k) + R27 (15k)
* 0.68 * C32 * (R26 + R27) = 3264us
*/
// #define C32_DISCHARGE_TIME (int)(32767 / 0.003264);
/* I think this is to short. Is C32 really 1u? */
#define C32_DISCHARGE_TIME (int)(32767 / 0.03264);
shot_amp_counter -= C32_DISCHARGE_TIME;
while( shot_amp_counter <= 0 )
{
shot_amp_counter += Machine->sample_rate;
if( --shot_amp == 0 )
break;
}
/* mix shot sound at 35% */
sum += vol_lookup[shot_amp] * 35 / 100;
}
}
if( (latch & 0x02) == 0 )
squeal_amp = 0;
else
{
if( squeal_amp < 32767 )
{
/* charge C5 (22u) over R3 (68k) and CR1 (1N914)
* time = 0.68 * C5 * R3 = 1017280us
*/
#define C5_CHARGE_TIME (int)(32767 / 1.01728);
squeal_amp_counter -= C5_CHARGE_TIME;
while( squeal_amp_counter <= 0 )
{
squeal_amp_counter += Machine->sample_rate;
if( ++squeal_amp == 32767 )
break;
}
}
if( squeal_out )
{
/* NE555 setup as pulse position modulator
* C = 0.01u, Ra = 33k, Rb = 47k
* frequency = 1.44 / ((33k + 2*47k) * 0.01u) = 1134Hz
* modulated by squeal_amp
*/
squeal_off_counter -= (1134 + 1134 * squeal_amp / 32767) / 3;
while( squeal_off_counter <= 0 )
{
squeal_off_counter += Machine->sample_rate;
squeal_out = 0;
}
}
else
{
squeal_on_counter -= 1134;
while( squeal_on_counter <= 0 )
{
squeal_on_counter += Machine->sample_rate;
squeal_out = 1;
}
}
}
/* mix sequal sound at 40% */
if( squeal_out )
sum += 32767 * 40 / 100;
*buffer++ = sum;
}
}
int redbaron_sh_start(const struct MachineSound *msound)
{
int i;
vol_lookup = (INT16 *)malloc(32768 * sizeof(INT16));
if( !vol_lookup )
return 1;
for( i = 0; i < 0x8000; i++ )
vol_lookup[0x7fff-i] = (INT16) (0x7fff/exp(1.0*i/4096));
for( i = 0; i < 16; i++ )
{
/* r0 = R18 and R24, r1 = open */
double r0 = 1.0/(5600 + 680), r1 = 1/6e12;
/* R14 */
if( i & 1 )
r1 += 1.0/8200;
else
r0 += 1.0/8200;
/* R15 */
if( i & 2 )
r1 += 1.0/3900;
else
r0 += 1.0/3900;
/* R16 */
if( i & 4 )
r1 += 1.0/2200;
else
r0 += 1.0/2200;
/* R17 */
if( i & 8 )
r1 += 1.0/1000;
else
r0 += 1.0/1000;
r0 = 1.0/r0;
r1 = 1.0/r1;
vol_crash[i] = 32767 * r0 / (r0 + r1);
}
channel = stream_init("Custom", 50, Machine->sample_rate, 0, redbaron_sound_update);
if( channel == -1 )
return 1;
return 0;
}
void redbaron_sh_stop(void)
{
if( vol_lookup )
free(vol_lookup);
vol_lookup = NULL;
}
void redbaron_sh_update(void)
{
stream_update(channel, 0);
}