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mdct_fixed.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 }