void ff_mdct_calc_c(FFTContext *s, FFTSample *out, const FFTSample *input)

{

    int i, j, n, n8, n4, n2, n3;

    FFTDouble re, im;

    const uint16_t *revtab = s->revtab;

    const FFTSample *tcos = s->tcos;

    const FFTSample *tsin = s->tsin;

    FFTComplex *x = (FFTComplex *)out;



    n = 1 << s->mdct_bits;

    n2 = n >> 1;

    n4 = n >> 2;

    n8 = n >> 3;

    n3 = 3 * n4;



    /* pre rotation */

    for(i=0;i<n8;i++) {

        re = RSCALE(-input[2*i+n3] - input[n3-1-2*i]);

        im = RSCALE(-input[n4+2*i] + input[n4-1-2*i]);

        j = revtab[i];

        CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);



        re = RSCALE( input[2*i]    - input[n2-1-2*i]);

        im = RSCALE(-input[n2+2*i] - input[ n-1-2*i]);

        j = revtab[n8 + i];

        CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);

    }



    s->fft_calc(s, x);



    /* post rotation */

    for(i=0;i<n8;i++) {

        FFTSample r0, i0, r1, i1;

        CMUL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);

        CMUL(i0, r1, x[n8+i  ].re, x[n8+i  ].im, -tsin[n8+i  ], -tcos[n8+i  ]);

        x[n8-i-1].re = r0;

        x[n8-i-1].im = i0;

        x[n8+i  ].re = r1;

        x[n8+i  ].im = i1;

    }

}
