libavcodec/mdct_fixed.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * Libav is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with Libav; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #define CONFIG_FFT_FLOAT 0
  20 #include "mdct.c"
  21
  22 /* same as ff_mdct_calcw_c with double-width unscaled output */
  23 void ff_mdct_calcw_c(FFTContext *s, FFTDouble *out, const FFTSample *input)
  24 {
  25     int i, j, n, n8, n4, n2, n3;
  26     FFTDouble re, im;
  27     const uint16_t *revtab = s->revtab;
  28     const FFTSample *tcos = s->tcos;
  29     const FFTSample *tsin = s->tsin;
  30     FFTComplex *x = s->tmp_buf;
  31     FFTDComplex *o = (FFTDComplex *)out;
  32
  33     n = 1 << s->mdct_bits;
  34     n2 = n >> 1;
  35     n4 = n >> 2;
  36     n8 = n >> 3;
  37     n3 = 3 * n4;
  38
  39     /* pre rotation */
  40     for(i=0;i<n8;i++) {
  41         re = RSCALE(-input[2*i+n3] - input[n3-1-2*i]);
  42         im = RSCALE(-input[n4+2*i] + input[n4-1-2*i]);
  43         j = revtab[i];
  44         CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
  45
  46         re = RSCALE( input[2*i]    - input[n2-1-2*i]);
  47         im = RSCALE(-input[n2+2*i] - input[ n-1-2*i]);
  48         j = revtab[n8 + i];
  49         CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
  50     }
  51
  52     s->fft_calc(s, x);
  53
  54     /* post rotation */
  55     for(i=0;i<n8;i++) {
  56         FFTDouble r0, i0, r1, i1;
  57         CMULL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);
  58         CMULL(i0, r1, x[n8+i  ].re, x[n8+i  ].im, -tsin[n8+i  ], -tcos[n8+i  ]);
  59         o[n8-i-1].re = r0;
  60         o[n8-i-1].im = i0;
  61         o[n8+i  ].re = r1;
  62         o[n8+i  ].im = i1;
  63     }
  64 }