ref: 0df3039072e1eb47d710348117063fa45cfaf2dd
dir: /modules/expon.c/
/* This code is placed in the public domain. */ #include <math.h> #include <stdlib.h> #include "soundpipe.h" int sp_expon_create(sp_expon **p) { *p = malloc(sizeof(sp_expon)); return SP_OK; } int sp_expon_destroy(sp_expon **p) { free(*p); return SP_OK; } static void expon_reinit(sp_data *sp, sp_expon *p) { SPFLOAT onedsr; p->stime = 0; p->sdur = p->dur * sp->sr; onedsr = 1.0 / sp->sr; if ((p->a * p->b) > 0.0) { p->incr = pow((SPFLOAT)(p->b / p->a), onedsr / p->dur); } else { p->incr = 1; p->val = p->a; } p->val = p->a; } int sp_expon_init(sp_data *sp, sp_expon *p) { p->a = 0.000001; p->b = 1; p->dur = 1; expon_reinit(sp, p); p->init = 1; return SP_OK; } int sp_expon_compute(sp_data *sp, sp_expon *p, SPFLOAT *in, SPFLOAT *out) { if (*in) { expon_reinit(sp, p); p->init = 0; } if (p->init) { *out = 0; return SP_OK; } if (p->stime < p->sdur) { SPFLOAT val = p->val; p->val *= p->incr; p->stime++; *out = val; } else { *out = p->b; } return SP_OK; }