From bb6f5690728486b71e280a295aef4c49d25ee758 Mon Sep 17 00:00:00 2001
From: Fabrice Bellard <fabrice@bellard.org>
Date: Mon, 28 Oct 2002 00:34:08 +0000
Subject: new generic FFT/MDCT code for audio codecs

Originally committed as revision 1088 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/fft-test.c | 294 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 294 insertions(+)
 create mode 100644 libavcodec/fft-test.c

(limited to 'libavcodec/fft-test.c')

diff --git a/libavcodec/fft-test.c b/libavcodec/fft-test.c
new file mode 100644
index 0000000000..3015c7a709
--- /dev/null
+++ b/libavcodec/fft-test.c
@@ -0,0 +1,294 @@
+/* FFT and MDCT tests */
+#include "dsputil.h"
+#include <math.h>
+#include <getopt.h>
+#include <sys/time.h>
+
+int mm_flags;
+
+void *av_malloc(int size)
+{
+    void *ptr;
+    ptr = malloc(size);
+    return ptr;
+}
+
+void av_free(void *ptr)
+{
+    /* XXX: this test should not be needed on most libcs */
+    if (ptr)
+        free(ptr);
+}
+
+/* cannot call it directly because of 'void **' casting is not automatic */
+void __av_freep(void **ptr)
+{
+    av_free(*ptr);
+    *ptr = NULL;
+}
+
+/* reference fft */
+
+#define MUL16(a,b) ((a) * (b))
+
+#define CMAC(pre, pim, are, aim, bre, bim) \
+{\
+   pre += (MUL16(are, bre) - MUL16(aim, bim));\
+   pim += (MUL16(are, bim) + MUL16(bre, aim));\
+}
+
+FFTComplex *exptab;
+
+void fft_ref_init(int nbits, int inverse)
+{
+    int n, i;
+    float c1, s1, alpha;
+
+    n = 1 << nbits;
+    exptab = av_malloc((n / 2) * sizeof(FFTComplex));
+
+    for(i=0;i<(n/2);i++) {
+        alpha = 2 * M_PI * (float)i / (float)n;
+        c1 = cos(alpha);
+        s1 = sin(alpha);
+        if (!inverse)
+            s1 = -s1;
+        exptab[i].re = c1;
+        exptab[i].im = s1;
+    }
+}
+
+void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits)
+{
+    int n, i, j, k, n2;
+    float tmp_re, tmp_im, s, c;
+    FFTComplex *q;
+
+    n = 1 << nbits;
+    n2 = n >> 1;
+    for(i=0;i<n;i++) {
+        tmp_re = 0;
+        tmp_im = 0;
+        q = tab;
+        for(j=0;j<n;j++) {
+            k = (i * j) & (n - 1);
+            if (k >= n2) {
+                c = -exptab[k - n2].re;
+                s = -exptab[k - n2].im;
+            } else {
+                c = exptab[k].re;
+                s = exptab[k].im;
+            }
+            CMAC(tmp_re, tmp_im, c, s, q->re, q->im);
+            q++;
+        }
+        tabr[i].re = tmp_re;
+        tabr[i].im = tmp_im;
+    }
+}
+
+void imdct_ref(float *out, float *in, int n)
+{
+    int k, i, a;
+    float sum, f;
+
+    for(i=0;i<n;i++) {
+        sum = 0;
+        for(k=0;k<n/2;k++) {
+            a = (2 * i + 1 + (n / 2)) * (2 * k + 1);
+            f = cos(M_PI * a / (double)(2 * n));
+            sum += f * in[k];
+        }
+        out[i] = -sum;
+    }
+}
+
+/* NOTE: no normalisation by 1 / N is done */
+void mdct_ref(float *output, float *input, int n)
+{
+    int k, i;
+    float a, s;
+
+    /* do it by hand */
+    for(k=0;k<n/2;k++) {
+        s = 0;
+        for(i=0;i<n;i++) {
+            a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n));
+            s += input[i] * cos(a);
+        }
+        output[k] = s;
+    }
+}
+
+
+float frandom(void)
+{
+    return (float)((random() & 0xffff) - 32768) / 32768.0;
+}
+
+INT64 gettime(void)
+{
+    struct timeval tv;
+    gettimeofday(&tv,NULL);
+    return (INT64)tv.tv_sec * 1000000 + tv.tv_usec;
+}
+
+void check_diff(float *tab1, float *tab2, int n)
+{
+    int i;
+
+    for(i=0;i<n;i++) {
+        if (fabsf(tab1[i] - tab2[i]) >= 1e-3) {
+            printf("ERROR %d: %f %f\n", 
+                   i, tab1[i], tab2[i]);
+        }
+    }
+}
+
+
+void help(void)
+{
+    printf("usage: fft-test [-h] [-s] [-i] [-n b]\n"
+           "-h     print this help\n"
+           "-s     speed test\n"
+           "-m     (I)MDCT test\n"
+           "-i     inverse transform test\n"
+           "-n b   set the transform size to 2^b\n"
+           );
+    exit(1);
+}
+
+
+
+int main(int argc, char **argv)
+{
+    FFTComplex *tab, *tab1, *tab_ref;
+    FFTSample *tabtmp, *tab2;
+    int it, i, c;
+    int do_speed = 0;
+    int do_mdct = 0;
+    int do_inverse = 0;
+    FFTContext s1, *s = &s1;
+    MDCTContext m1, *m = &m1;
+    int fft_nbits, fft_size;
+
+    mm_flags = 0;
+    fft_nbits = 9;
+    for(;;) {
+        c = getopt(argc, argv, "hsimn:");
+        if (c == -1)
+            break;
+        switch(c) {
+        case 'h':
+            help();
+            break;
+        case 's':
+            do_speed = 1;
+            break;
+        case 'i':
+            do_inverse = 1;
+            break;
+        case 'm':
+            do_mdct = 1;
+            break;
+        case 'n':
+            fft_nbits = atoi(optarg);
+            break;
+        }
+    }
+
+    fft_size = 1 << fft_nbits;
+    tab = av_malloc(fft_size * sizeof(FFTComplex));
+    tab1 = av_malloc(fft_size * sizeof(FFTComplex));
+    tab_ref = av_malloc(fft_size * sizeof(FFTComplex));
+    tabtmp = av_malloc(fft_size / 2 * sizeof(FFTSample));
+    tab2 = av_malloc(fft_size * sizeof(FFTSample));
+
+    if (do_mdct) {
+        if (do_inverse)
+            printf("IMDCT");
+        else
+            printf("MDCT");
+        mdct_init(m, fft_nbits, do_inverse);
+    } else {
+        if (do_inverse)
+            printf("IFFT");
+        else
+            printf("FFT");
+        fft_init(s, fft_nbits, do_inverse);
+        fft_ref_init(fft_nbits, do_inverse);
+    }
+    printf(" %d test\n", fft_size);
+
+    /* generate random data */
+
+    for(i=0;i<fft_size;i++) {
+        tab1[i].re = frandom();
+        tab1[i].im = frandom();
+    }
+
+    /* checking result */
+    printf("Checking...\n");
+
+    if (do_mdct) {
+        if (do_inverse) {
+            imdct_ref((float *)tab_ref, (float *)tab1, fft_size);
+            imdct_calc(m, tab2, (float *)tab1, tabtmp);
+            check_diff((float *)tab_ref, tab2, fft_size);
+        } else {
+            mdct_ref((float *)tab_ref, (float *)tab1, fft_size);
+            
+            mdct_calc(m, tab2, (float *)tab1, tabtmp);
+
+            check_diff((float *)tab_ref, tab2, fft_size / 2);
+        }
+    } else {
+        memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
+        fft_permute(s, tab);
+        fft_calc(s, tab);
+        
+        fft_ref(tab_ref, tab1, fft_nbits);
+        check_diff((float *)tab_ref, (float *)tab, fft_size * 2);
+    }
+
+    /* do a speed test */
+
+    if (do_speed) {
+        INT64 time_start, duration;
+        int nb_its;
+
+        printf("Speed test...\n");
+        /* we measure during about 1 seconds */
+        nb_its = 1;
+        for(;;) {
+            time_start = gettime();
+            for(it=0;it<nb_its;it++) {
+                if (do_mdct) {
+                    if (do_inverse) {
+                        imdct_calc(m, (float *)tab, (float *)tab1, tabtmp);
+                    } else {
+                        mdct_calc(m, (float *)tab, (float *)tab1, tabtmp);
+                    }
+                } else {
+                    memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
+                    fft_calc(s, tab);
+                }
+            }
+            duration = gettime() - time_start;
+            if (duration >= 1000000)
+                break;
+            nb_its *= 2;
+        }
+        printf("time: %0.1f us/transform [total time=%0.2f s its=%d]\n", 
+               (double)duration / nb_its, 
+               (double)duration / 1000000.0,
+               nb_its);
+    }
+    
+    if (do_mdct) {
+        mdct_end(m);
+    } else {
+        fft_end(s);
+    }
+    return 0;
+}
-- 
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