95be5f62e3a8f9e2303019bbec32fe78e9837a78
[libav.git] / libavcodec / acelp_math.h
1 /*
2 * Various fixed-point math operations
3 *
4 * Copyright (c) 2008 Vladimir Voroshilov
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #ifndef FFMPEG_ACELP_MATH_H
24 #define FFMPEG_ACELP_MATH_H
25
26 /**
27 * \brief fixed-point implementation of cosine in [0; PI) domain
28 * \param arg fixed-point cosine argument, 0 <= arg < 0x4000
29 *
30 * \return value of (1<<15) * cos(arg * PI / (1<<14)), -0x8000 <= result <= 0x7fff
31 */
32 int16_t ff_cos(uint16_t arg);
33
34 /**
35 * \brief fixed-point implementation of exp2(x) in [0; 1] domain
36 * \param power argument to exp2, 0 <= power <= 0x7fff
37 *
38 * \return value of (1<<20) * exp2(power / (1<<15))
39 * 0x8000c <= result <= 0xfffea
40 */
41 int ff_exp2(uint16_t power);
42
43 /**
44 * \brief Calculates log2(x)
45 * \param value function argument, 0 < value <= 7fff ffff
46 *
47 * \return value of (1<<15) * log2(value)
48 */
49 int ff_log2(uint32_t value);
50
51 /**
52 * \brief Calculates sum of array element multiplications
53 * \param speech input data array
54 * \param length number of elements
55 * \param offset offset for calculation of sum of s[i]*s[i+offset]
56 * \param shift right shift by this value will be done before multiplication
57 *
58 * \return sum of multiplications
59 *
60 * \note array must be at least length+offset long!
61 */
62 static int sum_of_squares(const int16_t* speech, int length, int offset, int shift)
63 {
64 const int16_t* speech_end;
65 int sum = 0;
66
67 for(speech_end=speech+length; speech<speech_end; speech++)
68 sum += (speech[0] * speech[offset]) >> shift;
69
70 return sum;
71 }
72
73 #endif // FFMPEG_ACELP_MATH_H