a7d006b637
The new code is based on timestamps, rather than delays. This eliminates the need to update every timer in timer_process(), which cost a non-trivial amount of CPU time on low-end machines. This involved changes to every user of the timer code, so this change almost certainly introduces bugs.
111 lines
2.3 KiB
C
111 lines
2.3 KiB
C
#include <stdlib.h>
|
|
#include "ibm.h"
|
|
#include "filters.h"
|
|
#include "lpt.h"
|
|
#include "lpt_dac.h"
|
|
#include "sound.h"
|
|
|
|
typedef struct dss_t
|
|
{
|
|
uint8_t fifo[16];
|
|
int read_idx, write_idx;
|
|
|
|
uint8_t dac_val;
|
|
|
|
pc_timer_t timer;
|
|
|
|
int16_t buffer[MAXSOUNDBUFLEN];
|
|
int pos;
|
|
} dss_t;
|
|
|
|
static void dss_update(dss_t *dss)
|
|
{
|
|
for (; dss->pos < sound_pos_global; dss->pos++)
|
|
dss->buffer[dss->pos] = (int8_t)(dss->dac_val ^ 0x80) * 0x40;
|
|
}
|
|
|
|
|
|
static void dss_write_data(uint8_t val, void *p)
|
|
{
|
|
dss_t *dss = (dss_t *)p;
|
|
|
|
if ((dss->write_idx - dss->read_idx) < 16)
|
|
{
|
|
dss->fifo[dss->write_idx & 15] = val;
|
|
dss->write_idx++;
|
|
}
|
|
}
|
|
|
|
static void dss_write_ctrl(uint8_t val, void *p)
|
|
{
|
|
}
|
|
|
|
static uint8_t dss_read_status(void *p)
|
|
{
|
|
dss_t *dss = (dss_t *)p;
|
|
|
|
if ((dss->write_idx - dss->read_idx) >= 16)
|
|
return 0x40;
|
|
return 0;
|
|
}
|
|
|
|
|
|
static void dss_get_buffer(int32_t *buffer, int len, void *p)
|
|
{
|
|
dss_t *dss = (dss_t *)p;
|
|
int c;
|
|
|
|
dss_update(dss);
|
|
|
|
for (c = 0; c < len*2; c += 2)
|
|
{
|
|
int16_t val = (int16_t)dss_iir((float)dss->buffer[c >> 1]);
|
|
|
|
buffer[c] += val;
|
|
buffer[c+1] += val;
|
|
}
|
|
|
|
dss->pos = 0;
|
|
}
|
|
|
|
static void dss_callback(void *p)
|
|
{
|
|
dss_t *dss = (dss_t *)p;
|
|
|
|
dss_update(dss);
|
|
|
|
if ((dss->write_idx - dss->read_idx) > 0)
|
|
{
|
|
dss->dac_val = dss->fifo[dss->read_idx & 15];
|
|
dss->read_idx++;
|
|
}
|
|
|
|
timer_advance_u64(&dss->timer, (TIMER_USEC * (1000000.0 / 7000.0)));
|
|
}
|
|
|
|
static void *dss_init()
|
|
{
|
|
dss_t *dss = malloc(sizeof(dss_t));
|
|
memset(dss, 0, sizeof(dss_t));
|
|
|
|
sound_add_handler(dss_get_buffer, dss);
|
|
timer_add(&dss->timer, dss_callback, dss, 1);
|
|
|
|
return dss;
|
|
}
|
|
static void dss_close(void *p)
|
|
{
|
|
dss_t *dss = (dss_t *)p;
|
|
|
|
free(dss);
|
|
}
|
|
|
|
lpt_device_t dss_device =
|
|
{
|
|
"Disney Sound Source",
|
|
dss_init,
|
|
dss_close,
|
|
dss_write_data,
|
|
dss_write_ctrl,
|
|
dss_read_status
|
|
};
|