void ff_imdct_calc(MDCTContext *s, FFTSample *output, const FFTSample *input, FFTSample *tmp) { int k, n8, n4, n2, n, j; const uint16_t *revtab = s->fft.revtab; const FFTSample *tcos = s->tcos; const FFTSample *tsin = s->tsin; const FFTSample *in1, *in2; FFTComplex *z = (FFTComplex *)tmp; n = 1 << s->nbits; n2 = n >> 1; n4 = n >> 2; n8 = n >> 3; /* pre rotation */ in1 = input; in2 = input + n2 - 1; for(k = 0; k < n4; k++) { j=revtab[k]; CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]); in1 += 2; in2 -= 2; } ff_fft_calc(&s->fft, z); /* post rotation + reordering */ /* XXX: optimize */ for(k = 0; k < n4; k++) { CMUL(z[k].re, z[k].im, z[k].re, z[k].im, tcos[k], tsin[k]); } for(k = 0; k < n8; k++) { output[2*k] = -z[n8 + k].im; output[n2-1-2*k] = z[n8 + k].im; output[2*k+1] = z[n8-1-k].re; output[n2-1-2*k-1] = -z[n8-1-k].re; output[n2 + 2*k]=-z[k+n8].re; output[n-1- 2*k]=-z[k+n8].re; output[n2 + 2*k+1]=z[n8-k-1].im; output[n-2 - 2 * k] = z[n8-k-1].im; } }