home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
AmigActive 10
/
AACD 10.iso
/
AACD
/
Games
/
MAME
/
src
/
sound
/
hc55516.c
< prev
next >
Wrap
C/C++ Source or Header
|
2000-04-04
|
5KB
|
194 lines
#include "driver.h"
#include <math.h>
#define INTEGRATOR_LEAK_TC 0.001
#define FILTER_DECAY_TC 0.004
#define FILTER_CHARGE_TC 0.004
#define FILTER_MIN 0.0416
#define FILTER_MAX 1.0954
#define SAMPLE_GAIN 10000.0
struct hc55516_data
{
INT8 channel;
UINT8 last_clock;
UINT8 databit;
UINT8 shiftreg;
INT16 curr_value;
INT16 next_value;
UINT32 update_count;
double filter;
double integrator;
};
static struct hc55516_data hc55516[MAX_HC55516];
static double charge, decay, leak;
static void hc55516_update(int num, INT16 *buffer, int length);
int hc55516_sh_start(const struct MachineSound *msound)
{
const struct hc55516_interface *intf = msound->sound_interface;
int i;
/* compute the fixed charge, decay, and leak time constants */
charge = pow(exp(-1), 1.0 / (FILTER_CHARGE_TC * 16000.0));
decay = pow(exp(-1), 1.0 / (FILTER_DECAY_TC * 16000.0));
leak = pow(exp(-1), 1.0 / (INTEGRATOR_LEAK_TC * 16000.0));
/* loop over HC55516 chips */
for (i = 0; i < intf->num; i++)
{
struct hc55516_data *chip = &hc55516[i];
char name[40];
/* reset the channel */
memset(chip, 0, sizeof(*chip));
/* create the stream */
sprintf(name, "HC55516 #%d", i);
chip->channel = stream_init(name, intf->volume[i] & 0xff, Machine->sample_rate, i, hc55516_update);
/* bail on fail */
if (chip->channel == -1)
return 1;
}
/* success */
return 0;
}
void hc55516_update(int num, INT16 *buffer, int length)
{
struct hc55516_data *chip = &hc55516[num];
INT32 data, slope;
int i;
/* zero-length? bail */
if (length == 0)
return;
/* track how many samples we've updated without a clock */
chip->update_count += length;
if (chip->update_count > Machine->sample_rate / 32)
{
chip->update_count = Machine->sample_rate;
chip->next_value = 0;
}
/* compute the interpolation slope */
data = chip->curr_value;
slope = ((INT32)chip->next_value - data) / length;
chip->curr_value = chip->next_value;
/* reset the sample count */
for (i = 0; i < length; i++, data += slope)
*buffer++ = data;
}
void hc55516_clock_w(int num, int state)
{
struct hc55516_data *chip = &hc55516[num];
int clock = state & 1, diffclock;
/* update the clock */
diffclock = clock ^ chip->last_clock;
chip->last_clock = clock;
/* speech clock changing (active on rising edge) */
if (diffclock && clock)
{
double integrator = chip->integrator, temp;
/* clear the update count */
chip->update_count = 0;
/* move the estimator up or down a step based on the bit */
if (chip->databit)
{
chip->shiftreg = ((chip->shiftreg << 1) | 1) & 7;
integrator += chip->filter;
}
else
{
chip->shiftreg = (chip->shiftreg << 1) & 7;
integrator -= chip->filter;
}
/* simulate leakage */
integrator *= leak;
/* if we got all 0's or all 1's in the last n bits, bump the step up */
if (chip->shiftreg == 0 || chip->shiftreg == 7)
{
chip->filter = FILTER_MAX - ((FILTER_MAX - chip->filter) * charge);
if (chip->filter > FILTER_MAX)
chip->filter = FILTER_MAX;
}
/* simulate decay */
else
{
chip->filter *= decay;
if (chip->filter < FILTER_MIN)
chip->filter = FILTER_MIN;
}
/* compute the sample as a 32-bit word */
temp = integrator * SAMPLE_GAIN;
chip->integrator = integrator;
/* compress the sample range to fit better in a 16-bit word */
if (temp < 0)
chip->next_value = (int)(temp / (-temp * (1.0 / 32768.0) + 1.0));
else
chip->next_value = (int)(temp / (temp * (1.0 / 32768.0) + 1.0));
/* update the output buffer before changing the registers */
stream_update(chip->channel, 0);
}
}
void hc55516_digit_w(int num, int data)
{
hc55516[num].databit = data & 1;
}
void hc55516_clock_clear_w(int num, int data)
{
hc55516_clock_w(num, 0);
}
void hc55516_clock_set_w(int num, int data)
{
hc55516_clock_w(num, 1);
}
void hc55516_digit_clock_clear_w(int num, int data)
{
hc55516[num].databit = data & 1;
hc55516_clock_w(num, 0);
}
WRITE_HANDLER( hc55516_0_digit_w ) { hc55516_digit_w(0,data); }
WRITE_HANDLER( hc55516_0_clock_w ) { hc55516_clock_w(0,data); }
WRITE_HANDLER( hc55516_0_clock_clear_w ) { hc55516_clock_clear_w(0,data); }
WRITE_HANDLER( hc55516_0_clock_set_w ) { hc55516_clock_set_w(0,data); }
WRITE_HANDLER( hc55516_0_digit_clock_clear_w ) { hc55516_digit_clock_clear_w(0,data); }