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#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <plibsys.h>
#include "channel.h"
void channel_init(struct channel_t *chan)
{
chan->active = false;
chan->paused = false;
chan->volume = 255;
chan->pan_left = -128;
chan->pan_right = 128;
chan->sound_mutex = p_mutex_new();
chan->sound.left = NULL;
chan->sound.right = NULL;
chan->pos = 0;
}
void channel_reset(struct channel_t *chan)
{
p_atomic_int_set(&(chan->paused), false);
p_atomic_int_set(&(chan->volume), 255);
p_atomic_int_set(&(chan->pan_left), -128);
p_atomic_int_set(&(chan->pan_right), 128);
chan->pos = 0;
p_atomic_int_set(&(chan->active), false);
}
void channel_pause(struct channel_t *chan)
{
p_atomic_int_set(&(chan->paused), true);
}
void channel_resume(struct channel_t *chan)
{
p_atomic_int_set(&(chan->paused), false);
}
void channel_set_volume(struct channel_t *chan, float volume)
{
if (volume > 1.0f) volume = 1.0f;
if (volume < 0.0f) volume = 0.0f;
p_atomic_int_set(&(chan->volume), 255*volume);
}
void channel_set_pan(struct channel_t *chan, float pan_left, float pan_right)
{
if (pan_left > 1.0f) pan_left = 1.0f;
if (pan_left < -1.0f) pan_left = -1.0f;
if (pan_right > 1.0f) pan_right = 1.0f;
if (pan_right < -1.0f) pan_right = -1.0f;
p_atomic_int_set(&(chan->pan_left), 128*pan_left);
p_atomic_int_set(&(chan->pan_right), 128*pan_right);
}
#define QUARTER_PI 0.785397
static void pan_gain(float *gain_l, float *gain_r, float pan)
{
float theta = (QUARTER_PI * pan) + QUARTER_PI; /* 0-PI/2 */
*gain_l = cos(theta);
*gain_r = sin(theta);
}
void channel_get_next_sample(float *left, float *right, struct channel_t *chan)
{
bool active = p_atomic_int_get(&(chan->active));
bool paused = p_atomic_int_get(&(chan->paused));
if (!active || paused) {
/* skip this channel */
*left = 0;
*right = 0;
return;
}
if (!p_mutex_trylock(chan->sound_mutex)) {
/* can't lock mutex, skip */
*left = 0;
*right = 0;
return;
}
float volume = ((float)p_atomic_int_get(&(chan->volume)))/255;
if (chan->sound.mono) {
float x = chan->sound.left[chan->pos];
float pan = ((float)p_atomic_int_get(&(chan->pan_left)))/128;
float gain_l, gain_r;
pan_gain(&gain_l, &gain_r, pan);
*left = volume * gain_l * x;
*right = volume * gain_r * x;
}
else {
float l, r;
l = chan->sound.left[chan->pos];
r = chan->sound.right[chan->pos];
float pan_l = ((float)p_atomic_int_get(&(chan->pan_left)))/128;
float pan_r = ((float)p_atomic_int_get(&(chan->pan_right)))/128;
float gain_ll, gain_lr, gain_rl, gain_rr;
pan_gain(&gain_ll, &gain_lr, pan_l);
pan_gain(&gain_rl, &gain_rr, pan_r);
*left = volume * ((gain_ll * l) + (gain_rl * r));
*right = volume * ((gain_lr * l) + (gain_rr * r));
}
chan->pos += 1;
if (chan->pos >= chan->sound.len) {
channel_reset(chan);
}
p_mutex_unlock(chan->sound_mutex);
}
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