Move ff_sqrt() to libavutil/intmath.h
[libav.git] / libavutil / intmath.h
1 /*
2 * Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
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 #ifndef AVUTIL_INTMATH_H
22 #define AVUTIL_INTMATH_H
23
24 #include "config.h"
25 #include "common.h"
26
27 extern const uint32_t ff_inverse[257];
28
29 #if ARCH_ARM
30 # include "arm/intmath.h"
31 #elif ARCH_X86
32 # include "x86/intmath.h"
33 #endif
34
35 #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
36
37 #ifndef av_log2
38
39 #define av_log2(x) (31 - __builtin_clz((x)|1))
40
41 #ifndef av_log2_16bit
42 #define av_log2_16bit av_log2
43 #endif
44
45 #endif /* av_log2 */
46
47 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
48
49 #ifndef FASTDIV
50
51 #if CONFIG_FASTDIV
52 # define FASTDIV(a,b) ((uint32_t)((((uint64_t)a) * ff_inverse[b]) >> 32))
53 #else
54 # define FASTDIV(a,b) ((a) / (b))
55 #endif
56
57 #endif /* FASTDIV */
58
59 extern const uint8_t ff_sqrt_tab[256];
60
61 static inline av_const unsigned int ff_sqrt(unsigned int a)
62 {
63 unsigned int b;
64
65 if (a < 255) return (ff_sqrt_tab[a + 1] - 1) >> 4;
66 else if (a < (1 << 12)) b = ff_sqrt_tab[a >> 4] >> 2;
67 #if !CONFIG_SMALL
68 else if (a < (1 << 14)) b = ff_sqrt_tab[a >> 6] >> 1;
69 else if (a < (1 << 16)) b = ff_sqrt_tab[a >> 8] ;
70 #endif
71 else {
72 int s = av_log2_16bit(a >> 16) >> 1;
73 unsigned int c = a >> (s + 2);
74 b = ff_sqrt_tab[c >> (s + 8)];
75 b = FASTDIV(c,b) + (b << s);
76 }
77
78 return b - (a < b * b);
79 }
80
81 #endif /* AVUTIL_INTMATH_H */