shithub: soundpipe

ref: a901d5647d30cf20fc0a096a612c58b2f99b8551
dir: /tangled/vardelay.c/

#line 18 "vardelay.org"
#include <math.h>
#include <stdlib.h>
#define SK_VARDELAY_PRIV
#include "vardelay.h"
#line 57 "vardelay.org"
void sk_vardelay_init(sk_vardelay *vd, int sr,
                      SKFLT *buf, unsigned long sz)
{
#line 92 "vardelay.org"
vd->sr = sr;
#line 112 "vardelay.org"
if (sz < 4) {
    vd->buf = NULL;
    vd->buf = 0;
} else {
    vd->buf = buf;
    vd->sz = sz;
}
#line 135 "vardelay.org"
vd->prev = 0;
#line 156 "vardelay.org"
vd->writepos = 0;
#line 185 "vardelay.org"
sk_vardelay_delay(vd, ((SKFLT)sz / sr) * 0.5);
#line 213 "vardelay.org"
sk_vardelay_feedback(vd, 0);
#line 61 "vardelay.org"
}
#line 169 "vardelay.org"
void sk_vardelay_delay(sk_vardelay *vd, SKFLT delay)
{
    vd->delay = delay;
}
#line 198 "vardelay.org"
void sk_vardelay_feedback(sk_vardelay *vd, SKFLT feedback)
{
    vd->feedback = feedback;
}
#line 225 "vardelay.org"
SKFLT sk_vardelay_tick(sk_vardelay *vd, SKFLT in)
{
    SKFLT out;
    SKFLT dels;
    SKFLT f;
    long i;
    SKFLT s[4];
    unsigned long n[4];
    SKFLT a, b, c, d;

    out = 0;
#line 254 "vardelay.org"
if (vd->buf == NULL || vd->sz == 0) return 0;
#line 225 "vardelay.org"
#line 261 "vardelay.org"
vd->buf[vd->writepos] = in + vd->prev * vd->feedback;
#line 225 "vardelay.org"
#line 274 "vardelay.org"
dels = vd->delay * vd->sr;
i = floor(dels);
f = i - dels;
i = vd->writepos - i;
#line 225 "vardelay.org"
#line 299 "vardelay.org"
if ((f < 0.0) || (i < 0)) {
    /* flip fractional component */
    f = f + 1.0;
    /* go backwards one sample */
    i = i - 1;
    while (i < 0) i += vd->sz;
} else while(i >= vd->sz) i -= vd->sz;
#line 225 "vardelay.org"
#line 313 "vardelay.org"
/* x(n) */
n[1] = i;

/* x(n + 1) */
if (i == (vd->sz - 1)) n[2] = 0;
else n[2] = n[1] + 1;

/* x(n - 1) */
if (i == 0) n[0] = vd->sz - 1;
else n[0] = i - 1;

if (n[2] == vd->sz - 1) n[3] = 0;
else n[3] = n[2] + 1;

{
    int j;
    for (j = 0; j < 4; j++) s[j] = vd->buf[n[j]];
}
#line 225 "vardelay.org"
#line 338 "vardelay.org"
{
    SKFLT tmp[2];

    d = ((f * f) - 1) * 0.1666666667;
    tmp[0] = (f + 1.0) * 0.5;
    tmp[1] = 3.0 * d;
    a = tmp[0] - 1.0 - d;
    c = tmp[0] - tmp[1];
    b = tmp[1] - f;
}
#line 225 "vardelay.org"
#line 358 "vardelay.org"
out = (a*s[0] + b*s[1] + c*s[2] + d*s[3]) * f + s[1];
#line 225 "vardelay.org"
#line 366 "vardelay.org"
vd->writepos++;
if (vd->writepos == vd->sz) vd->writepos = 0;
#line 225 "vardelay.org"
#line 375 "vardelay.org"
vd->prev = out;
#line 245 "vardelay.org"

    return out;
}
#line 18 "vardelay.org"