1/*
2 * copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include "fft.h"
22#include "synth_filter.h"
23
24static void synth_filter_float(FFTContext *imdct,
25                           float *synth_buf_ptr, int *synth_buf_offset,
26                           float synth_buf2[32], const float window[512],
27                           float out[32], const float in[32], float scale, float bias)
28{
29    float *synth_buf= synth_buf_ptr + *synth_buf_offset;
30    int i, j;
31
32    ff_imdct_half(imdct, synth_buf, in);
33
34    for (i = 0; i < 16; i++){
35        float a= synth_buf2[i     ];
36        float b= synth_buf2[i + 16];
37        float c= 0;
38        float d= 0;
39        for (j = 0; j < 512 - *synth_buf_offset; j += 64){
40            a += window[i + j     ]*(-synth_buf[15 - i + j      ]);
41            b += window[i + j + 16]*( synth_buf[     i + j      ]);
42            c += window[i + j + 32]*( synth_buf[16 + i + j      ]);
43            d += window[i + j + 48]*( synth_buf[31 - i + j      ]);
44        }
45        for (     ; j < 512; j += 64){
46            a += window[i + j     ]*(-synth_buf[15 - i + j - 512]);
47            b += window[i + j + 16]*( synth_buf[     i + j - 512]);
48            c += window[i + j + 32]*( synth_buf[16 + i + j - 512]);
49            d += window[i + j + 48]*( synth_buf[31 - i + j - 512]);
50        }
51        out[i     ] = a*scale + bias;
52        out[i + 16] = b*scale + bias;
53        synth_buf2[i     ] = c;
54        synth_buf2[i + 16] = d;
55    }
56    *synth_buf_offset= (*synth_buf_offset - 32)&511;
57}
58
59av_cold void ff_synth_filter_init(SynthFilterContext *c)
60{
61    c->synth_filter_float = synth_filter_float;
62
63    if (ARCH_ARM) ff_synth_filter_init_arm(c);
64}
65