/* This code is placed in the public domain. */ #include <math.h>#include "soundpipe.h"#include "kiss_fftr.h" #ifndef M_PI#define M_PI		3.14159265358979323846#endif int sp_gen_scrambler(sp_data *sp, sp_ftbl *src, sp_ftbl **dest){     uint32_t size;    sp_ftbl *dst;    kiss_fftr_cfg fft, ifft;    kiss_fft_cpx *tmp;    uint32_t i;    SPFLOAT mag, phs;    SPFLOAT max;    SPFLOAT val;     size = (src->size % 2 == 0) ? src->size : src->size - 1;    sp_ftbl_create(sp, &dst, size);     /* set up kissfft */    fft = kiss_fftr_alloc(size, 0, NULL, NULL);    ifft = kiss_fftr_alloc(size, 1, NULL, NULL);    tmp = malloc(sizeof(kiss_fft_cpx) * size);    memset(tmp, 0, sizeof(SPFLOAT) * size);    kiss_fftr(fft, src->tbl, tmp);     for(i = 0; i < size / 2; i++) {        mag = sqrt(tmp[i].r * tmp[i].r + tmp[i].i * tmp[i].i) / size;        phs = ((SPFLOAT)sp_rand(sp) / SP_RANDMAX) * 2 * M_PI;        tmp[i].r = mag * cos(phs);        tmp[i].i = mag * sin(phs);    }     tmp[0].r = 0;    tmp[0].i = 0;    tmp[size / 2 - 1].r = 0;    tmp[size / 2 - 1].i = 0;     kiss_fftri(ifft, tmp, dst->tbl);    max = -1;    for(i = 0; i < size; i++) {        val = fabs(dst->tbl[i]);        if(val > max) {            max = val;        }    }     for(i = 0; i < size; i++) {       dst->tbl[i] /= max;    }     kiss_fftr_free(fft);    kiss_fftr_free(ifft);    KISS_FFT_FREE(tmp);     *dest = dst;    return SP_OK;}