/* This code is placed in the public domain. */ #include <stdlib.h>#include "soundpipe.h" enum {    T_ON,    T_OFF,    T_INIT}; int sp_tenv2_create(sp_tenv2 **p){    *p = malloc(sizeof(sp_tenv2));    return SP_OK;} int sp_tenv2_destroy(sp_tenv2 **p){    free(*p);    return SP_OK;} int sp_tenv2_init(sp_data *sp, sp_tenv2 *p){    USED(sp);     p->state = T_INIT;    p->atk = 0.1;    p->rel = 0.1;    p->slope = 0;    p->last = 0;    return SP_OK;} int sp_tenv2_compute(sp_data *sp, sp_tenv2 *p, SPFLOAT *in, SPFLOAT *out){    if(*in != 0) {        if(p->state == T_INIT || p->state == T_OFF) {            p->state = T_ON;            p->timer = (uint32_t)(sp->sr * p->atk);            p->totaltime = p->timer;            p->slope = 1.0 / p->totaltime;        } else if (p->state == T_ON) {            p->state = T_OFF;            p->timer = (uint32_t)(sp->sr * p->rel);            p->totaltime = p->timer;            p->slope = 1.0 / p->totaltime;        }    }    if(p->timer == 0) {        if(p->state == T_ON) *out = 1;        else *out = 0;    } else {        p->timer--;        if(p->state == T_ON)  {            *out = p->last + p->slope;        } else if (p->state == T_OFF) {            *out = p->last - p->slope;        }         if(*out > 1) *out = 1;        if(*out < 0) *out = 0;         p->last = *out;    }    return SP_OK;}