ffmpeg / libavcodec / ffttest.c @ bec89a84
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/**


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* @file ffttest.c

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* FFT and MDCT tests.

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*/

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#include "dsputil.h" 
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#include <math.h> 
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#include <unistd.h> 
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#include <sys/time.h> 
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int mm_flags;

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/* reference fft */

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#define MUL16(a,b) ((a) * (b))

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#define CMAC(pre, pim, are, aim, bre, bim) \

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{\ 
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pre += (MUL16(are, bre)  MUL16(aim, bim));\ 
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pim += (MUL16(are, bim) + MUL16(bre, aim));\ 
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} 
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FFTComplex *exptab; 
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void fft_ref_init(int nbits, int inverse) 
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{ 
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int n, i;

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float c1, s1, alpha;

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n = 1 << nbits;

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exptab = av_malloc((n / 2) * sizeof(FFTComplex)); 
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for(i=0;i<(n/2);i++) { 
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alpha = 2 * M_PI * (float)i / (float)n; 
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c1 = cos(alpha); 
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s1 = sin(alpha); 
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if (!inverse)

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s1 = s1; 
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exptab[i].re = c1; 
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exptab[i].im = s1; 
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} 
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} 
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void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits) 
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{ 
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int n, i, j, k, n2;

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float tmp_re, tmp_im, s, c;

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FFTComplex *q; 
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n = 1 << nbits;

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n2 = n >> 1;

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for(i=0;i<n;i++) { 
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tmp_re = 0;

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tmp_im = 0;

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q = tab; 
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for(j=0;j<n;j++) { 
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k = (i * j) & (n  1);

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if (k >= n2) {

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c = exptab[k  n2].re; 
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s = exptab[k  n2].im; 
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} else {

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c = exptab[k].re; 
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s = exptab[k].im; 
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} 
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CMAC(tmp_re, tmp_im, c, s, q>re, q>im); 
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q++; 
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} 
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tabr[i].re = tmp_re; 
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tabr[i].im = tmp_im; 
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} 
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} 
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void imdct_ref(float *out, float *in, int n) 
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{ 
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int k, i, a;

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float sum, f;

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for(i=0;i<n;i++) { 
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sum = 0;

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for(k=0;k<n/2;k++) { 
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a = (2 * i + 1 + (n / 2)) * (2 * k + 1); 
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f = cos(M_PI * a / (double)(2 * n)); 
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sum += f * in[k]; 
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} 
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out[i] = sum; 
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} 
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} 
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/* NOTE: no normalisation by 1 / N is done */

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void mdct_ref(float *output, float *input, int n) 
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{ 
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int k, i;

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float a, s;

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/* do it by hand */

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for(k=0;k<n/2;k++) { 
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s = 0;

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for(i=0;i<n;i++) { 
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a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n)); 
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s += input[i] * cos(a); 
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} 
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output[k] = s; 
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} 
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} 
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float frandom(void) 
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{ 
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return (float)((random() & 0xffff)  32768) / 32768.0; 
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} 
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int64_t gettime(void)

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{ 
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struct timeval tv;

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gettimeofday(&tv,NULL);

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return (int64_t)tv.tv_sec * 1000000 + tv.tv_usec; 
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} 
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void check_diff(float *tab1, float *tab2, int n) 
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{ 
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int i;

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for(i=0;i<n;i++) { 
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if (fabsf(tab1[i]  tab2[i]) >= 1e3) { 
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printf("ERROR %d: %f %f\n",

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i, tab1[i], tab2[i]); 
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} 
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} 
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} 
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void help(void) 
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{ 
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printf("usage: ffttest [h] [s] [i] [n b]\n"

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"h print this help\n"

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"s speed test\n"

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"m (I)MDCT test\n"

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"i inverse transform test\n"

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"n b set the transform size to 2^b\n"

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); 
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exit(1);

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} 
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int main(int argc, char **argv) 
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{ 
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FFTComplex *tab, *tab1, *tab_ref; 
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FFTSample *tabtmp, *tab2; 
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int it, i, c;

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int do_speed = 0; 
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int do_mdct = 0; 
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int do_inverse = 0; 
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FFTContext s1, *s = &s1; 
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MDCTContext m1, *m = &m1; 
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int fft_nbits, fft_size;

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mm_flags = 0;

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fft_nbits = 9;

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for(;;) {

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c = getopt(argc, argv, "hsimn:");

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if (c == 1) 
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break;

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switch(c) {

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case 'h': 
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help(); 
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break;

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case 's': 
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do_speed = 1;

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break;

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case 'i': 
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do_inverse = 1;

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break;

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case 'm': 
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do_mdct = 1;

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break;

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case 'n': 
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fft_nbits = atoi(optarg); 
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break;

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} 
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} 
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fft_size = 1 << fft_nbits;

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tab = av_malloc(fft_size * sizeof(FFTComplex));

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tab1 = av_malloc(fft_size * sizeof(FFTComplex));

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tab_ref = av_malloc(fft_size * sizeof(FFTComplex));

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tabtmp = av_malloc(fft_size / 2 * sizeof(FFTSample)); 
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tab2 = av_malloc(fft_size * sizeof(FFTSample));

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if (do_mdct) {

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if (do_inverse)

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printf("IMDCT");

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else

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printf("MDCT");

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ff_mdct_init(m, fft_nbits, do_inverse); 
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} else {

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if (do_inverse)

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printf("IFFT");

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else

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printf("FFT");

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fft_init(s, fft_nbits, do_inverse); 
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fft_ref_init(fft_nbits, do_inverse); 
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} 
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printf(" %d test\n", fft_size);

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/* generate random data */

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for(i=0;i<fft_size;i++) { 
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tab1[i].re = frandom(); 
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tab1[i].im = frandom(); 
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} 
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/* checking result */

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printf("Checking...\n");

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if (do_mdct) {

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if (do_inverse) {

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imdct_ref((float *)tab_ref, (float *)tab1, fft_size); 
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ff_imdct_calc(m, tab2, (float *)tab1, tabtmp);

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check_diff((float *)tab_ref, tab2, fft_size);

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} else {

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mdct_ref((float *)tab_ref, (float *)tab1, fft_size); 
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ff_mdct_calc(m, tab2, (float *)tab1, tabtmp);

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check_diff((float *)tab_ref, tab2, fft_size / 2); 
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} 
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} else {

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memcpy(tab, tab1, fft_size * sizeof(FFTComplex));

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fft_permute(s, tab); 
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fft_calc(s, tab); 
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fft_ref(tab_ref, tab1, fft_nbits); 
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check_diff((float *)tab_ref, (float *)tab, fft_size * 2); 
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} 
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/* do a speed test */

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if (do_speed) {

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int64_t time_start, duration; 
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int nb_its;

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printf("Speed test...\n");

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/* we measure during about 1 seconds */

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nb_its = 1;

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for(;;) {

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time_start = gettime(); 
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for(it=0;it<nb_its;it++) { 
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if (do_mdct) {

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if (do_inverse) {

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ff_imdct_calc(m, (float *)tab, (float *)tab1, tabtmp); 
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} else {

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ff_mdct_calc(m, (float *)tab, (float *)tab1, tabtmp); 
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} 
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} else {

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memcpy(tab, tab1, fft_size * sizeof(FFTComplex));

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fft_calc(s, tab); 
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} 
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} 
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duration = gettime()  time_start; 
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if (duration >= 1000000) 
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break;

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nb_its *= 2;

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} 
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printf("time: %0.1f us/transform [total time=%0.2f s its=%d]\n",

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(double)duration / nb_its,

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(double)duration / 1000000.0, 
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nb_its); 
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} 
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if (do_mdct) {

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ff_mdct_end(m); 
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} else {

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fft_end(s); 
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} 
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return 0; 
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} 