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/* gcc -shared -I ~/include sin.c -o sin.so */
#include <stdlib.h>
#include <math.h>
#include <jack.dl.h>
struct sinosc {
float f; /* frequency */
float a; /* amplitude */
float p; /* pan */
float phase; /* oscillator phase */
};
#define TWO_PI (2 * M_PI)
/* convert frequency in hertz to phase increment in radians */
float hz_to_incr(float hz, float sr)
{
return (TWO_PI / sr) * hz;
}
/* increment phase within (0,2pi) */
float step_phasor(float *phase, float incr)
{
*phase += incr;
if(*phase > TWO_PI) {
*phase -= TWO_PI;
}
}
/* allocate state data and initialize private control data */
void *dsp_init(struct world *w, int g)
{
struct sinosc *s = malloc(sizeof(struct sinosc));
s->phase = 0.0;
s->f = 440.0;
s->a = 0.1;
s->p = 0.5;
w_p_set1(w, g, 0, s->f);
w_p_set1(w, g, 1, s->a);
w_p_set1(w, g, 2, s->p);
return (void*)s;
}
/* process nf frames of data */
void dsp_step(struct world *w, int g, void *ptr, int nf)
{
int i;
struct sinosc *s = (struct sinosc *)ptr;
/* load state */
float f = s->f;
float a = s->a;
float p = s->p;
float phase = s->phase;
/* read control values */
float fe = w_p_get1(w, g, 0);
float ae = w_p_get1(w, g, 1);
float pe = w_p_get1(w, g, 2);
/* calculate control increments */
float fi = (fe - f) / (float)nf;
float ai = (ae - a) / (float)nf;
float pi = (pe - p) / (float)nf;
for(i = 0; i < nf; i++) {
/* algorithm */
float n = sinf(phase) * a;
w_out2(w, i, n * p, n * (1 - p));
float incr = hz_to_incr(f, w_sr(w));
step_phasor(&phase, incr);
/* apply control increments */
f += fi;
a += ai;
p += pi;
}
/* store state */
s->f = fe;
s->a = ae;
s->p = pe;
s->phase = phase;
}
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