* (Inverse) Real Discrete Fourier Transforms.
*/
-/* sin(2*pi*x/n) for 0<=x<n/4, followed by n/2<=x<3n/4 */
-#if !CONFIG_HARDCODED_TABLES
-SINTABLE(16);
-SINTABLE(32);
-SINTABLE(64);
-SINTABLE(128);
-SINTABLE(256);
-SINTABLE(512);
-SINTABLE(1024);
-SINTABLE(2048);
-SINTABLE(4096);
-SINTABLE(8192);
-SINTABLE(16384);
-SINTABLE(32768);
-SINTABLE(65536);
-#endif
-static SINTABLE_CONST FFTSample * const ff_sin_tabs[] = {
- NULL, NULL, NULL, NULL,
- ff_sin_16, ff_sin_32, ff_sin_64, ff_sin_128, ff_sin_256, ff_sin_512, ff_sin_1024,
- ff_sin_2048, ff_sin_4096, ff_sin_8192, ff_sin_16384, ff_sin_32768, ff_sin_65536,
-};
-
/** Map one real FFT into two parallel real even and odd FFTs. Then interleave
* the two real FFTs into one complex FFT. Unmangle the results.
* ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM
static void rdft_calc_c(RDFTContext *s, FFTSample *data)
{
int i, i1, i2;
- FFTComplex ev, od;
+ FFTComplex ev, od, odsum;
const int n = 1 << s->nbits;
const float k1 = 0.5;
const float k2 = 0.5 - s->inverse;
ev.re = data[0];
data[0] = ev.re+data[1];
data[1] = ev.re-data[1];
- for (i = 1; i < (n>>2); i++) {
- i1 = 2*i;
- i2 = n-i1;
- /* Separate even and odd FFTs */
- ev.re = k1*(data[i1 ]+data[i2 ]);
- od.im = -k2*(data[i1 ]-data[i2 ]);
- ev.im = k1*(data[i1+1]-data[i2+1]);
- od.re = k2*(data[i1+1]+data[i2+1]);
- /* Apply twiddle factors to the odd FFT and add to the even FFT */
- data[i1 ] = ev.re + od.re*tcos[i] - od.im*tsin[i];
- data[i1+1] = ev.im + od.im*tcos[i] + od.re*tsin[i];
- data[i2 ] = ev.re - od.re*tcos[i] + od.im*tsin[i];
- data[i2+1] = -ev.im + od.im*tcos[i] + od.re*tsin[i];
+
+#define RDFT_UNMANGLE(sign0, sign1) \
+ for (i = 1; i < (n>>2); i++) { \
+ i1 = 2*i; \
+ i2 = n-i1; \
+ /* Separate even and odd FFTs */ \
+ ev.re = k1*(data[i1 ]+data[i2 ]); \
+ od.im = k2*(data[i2 ]-data[i1 ]); \
+ ev.im = k1*(data[i1+1]-data[i2+1]); \
+ od.re = k2*(data[i1+1]+data[i2+1]); \
+ /* Apply twiddle factors to the odd FFT and add to the even FFT */ \
+ odsum.re = od.re*tcos[i] sign0 od.im*tsin[i]; \
+ odsum.im = od.im*tcos[i] sign1 od.re*tsin[i]; \
+ data[i1 ] = ev.re + odsum.re; \
+ data[i1+1] = ev.im + odsum.im; \
+ data[i2 ] = ev.re - odsum.re; \
+ data[i2+1] = odsum.im - ev.im; \
+ }
+
+ if (s->negative_sin) {
+ RDFT_UNMANGLE(+,-)
+ } else {
+ RDFT_UNMANGLE(-,+)
}
+
data[2*i+1]=s->sign_convention*data[2*i+1];
if (s->inverse) {
data[0] *= k1;
s->nbits = nbits;
s->inverse = trans == IDFT_C2R || trans == DFT_C2R;
s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1;
+ s->negative_sin = trans == DFT_C2R || trans == DFT_R2C;
if (nbits < 4 || nbits > 16)
return AVERROR(EINVAL);
ff_init_ff_cos_tabs(nbits);
s->tcos = ff_cos_tabs[nbits];
- s->tsin = ff_sin_tabs[nbits]+(trans == DFT_R2C || trans == DFT_C2R)*(n>>2);
-#if !CONFIG_HARDCODED_TABLES
- {
- int i;
- const double theta = (trans == DFT_R2C || trans == DFT_C2R ? -1 : 1) * 2 * M_PI / n;
- for (i = 0; i < (n >> 2); i++)
- s->tsin[i] = sin(i * theta);
- }
-#endif
+ s->tsin = ff_cos_tabs[nbits] + (n >> 2);
s->rdft_calc = rdft_calc_c;
if (ARCH_ARM) ff_rdft_init_arm(s);