avcodec/avfft: Add simple self test

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/Makefile

@@ -862,6 +862,7 @@ SKIPHEADERS-$(CONFIG_VDPAU)            += vdpau.h vdpau_internal.h
 
 TESTPROGS = imgconvert                                                  \
             options                                                     \
+            avfft                                                       \
 
 
 TESTPROGS-$(CONFIG_CABAC)                 += cabac

libavcodec/avfft.c

@@ -142,4 +142,38 @@ av_cold void av_dct_end(DCTContext *s)
     }
 }
 
+#ifdef TEST
+int main(int argc, char **argv)
+{
+    int i;
+#define LEN 1024
+    FFTSample *ref  = av_malloc_array(LEN, sizeof(*ref));
+    FFTSample *data = av_malloc_array(LEN, sizeof(*data));
+    RDFTContext *rdft_context  = av_rdft_init(10, DFT_R2C);
+    RDFTContext *irdft_context = av_rdft_init(10, IDFT_C2R);
+
+    if (!ref || !data || !rdft_context || !irdft_context)
+        return 2;
+    for (i=0; i<LEN; i++) {
+        ref[i] = data[i] = i*456 + 123 + i*i;
+    }
+    av_rdft_calc(rdft_context, data);
+    av_rdft_calc(irdft_context, data);
+
+    for (i=0; i<LEN; i++) {
+        if (fabs(ref[i] - data[i]/LEN*2) > 1) {
+            fprintf(stderr, "Failed at %d (%f %f)\n", i, ref[i], data[i]/LEN*2);
+            return 1;
+        }
+    }
+
+    av_rdft_end(rdft_context);
+    av_rdft_end(irdft_context);
+    av_free(data);
+    av_free(ref);
+
+    return 0;
+}
+#endif
+
 #endif /* CONFIG_DCT */