2 * Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
4 * This file is part of FFmpeg.
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.
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.
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
21 #ifndef AVUTIL_INTMATH_H
22 #define AVUTIL_INTMATH_H
26 #include "attributes.h"
28 extern const uint32_t ff_inverse[257];
31 # include "arm/intmath.h"
33 # include "x86/intmath.h"
36 #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4)
39 # define av_log2(x) (31 - __builtin_clz((x)|1))
40 # ifndef av_log2_16bit
41 # define av_log2_16bit av_log2
45 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
49 # define FASTDIV(a,b) ((uint32_t)((((uint64_t)a) * ff_inverse[b]) >> 32))
51 # define FASTDIV(a,b) ((a) / (b))
57 extern const uint8_t ff_sqrt_tab[256];
59 static inline av_const unsigned int ff_sqrt(unsigned int a)
63 if (a < 255) return (ff_sqrt_tab[a + 1] - 1) >> 4;
64 else if (a < (1 << 12)) b = ff_sqrt_tab[a >> 4] >> 2;
66 else if (a < (1 << 14)) b = ff_sqrt_tab[a >> 6] >> 1;
67 else if (a < (1 << 16)) b = ff_sqrt_tab[a >> 8] ;
70 int s = av_log2_16bit(a >> 16) >> 1;
71 unsigned int c = a >> (s + 2);
72 b = ff_sqrt_tab[c >> (s + 8)];
73 b = FASTDIV(c,b) + (b << s);
76 return b - (a < b * b);
79 #endif /* AVUTIL_INTMATH_H */