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fft_init_table.c
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1 /*
2  * Copyright (c) 2012
3  * MIPS Technologies, Inc., California.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the MIPS Technologies, Inc., nor the names of its
14  * contributors may be used to endorse or promote products derived from
15  * this software without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE MIPS TECHNOLOGIES, INC. ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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28  *
29  * Author: Stanislav Ocovaj (socovaj@mips.com)
30  *
31  * This file is part of FFmpeg.
32  *
33  * FFmpeg is free software; you can redistribute it and/or
34  * modify it under the terms of the GNU Lesser General Public
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37  *
38  * FFmpeg is distributed in the hope that it will be useful,
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40  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
41  * Lesser General Public License for more details.
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43  * You should have received a copy of the GNU Lesser General Public
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46  */
47 
48 /**
49  * @file
50  * definitions and initialization of LUT table for MIPS FFT
51  */
52 #include "fft_table.h"
53 
54 uint16_t fft_offsets_lut[0x2aab];
55 
56 void ff_fft_lut_init(uint16_t *table, int off, int size, int *index)
57 {
58  if (size < 16) {
59  table[*index] = off >> 2;
60  (*index)++;
61  }
62  else {
63  ff_fft_lut_init(table, off, size>>1, index);
64  ff_fft_lut_init(table, off+(size>>1), size>>2, index);
65  ff_fft_lut_init(table, off+3*(size>>2), size>>2, index);
66  }
67 }