Libav 0.7.1
|
00001 /* 00002 * Copyright (c) 2010 Mans Rullgard <mans@mansr.com> 00003 * 00004 * This file is part of Libav. 00005 * 00006 * Libav is free software; you can redistribute it and/or 00007 * modify it under the terms of the GNU Lesser General Public 00008 * License as published by the Free Software Foundation; either 00009 * version 2.1 of the License, or (at your option) any later version. 00010 * 00011 * Libav is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00014 * Lesser General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU Lesser General Public 00017 * License along with Libav; if not, write to the Free Software 00018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00019 */ 00020 00021 #ifndef AVUTIL_INTMATH_H 00022 #define AVUTIL_INTMATH_H 00023 00024 #include <stdint.h> 00025 #include "config.h" 00026 #include "attributes.h" 00027 00028 extern const uint32_t ff_inverse[257]; 00029 00030 #if ARCH_ARM 00031 # include "arm/intmath.h" 00032 #elif ARCH_X86 00033 # include "x86/intmath.h" 00034 #endif 00035 00036 #if HAVE_FAST_CLZ && AV_GCC_VERSION_AT_LEAST(3,4) 00037 00038 #ifndef av_log2 00039 # define av_log2(x) (31 - __builtin_clz((x)|1)) 00040 # ifndef av_log2_16bit 00041 # define av_log2_16bit av_log2 00042 # endif 00043 #endif /* av_log2 */ 00044 00045 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */ 00046 00047 #ifndef FASTDIV 00048 # if CONFIG_FASTDIV 00049 # define FASTDIV(a,b) ((uint32_t)((((uint64_t)a) * ff_inverse[b]) >> 32)) 00050 # else 00051 # define FASTDIV(a,b) ((a) / (b)) 00052 # endif 00053 #endif /* FASTDIV */ 00054 00055 #include "common.h" 00056 00057 extern const uint8_t ff_sqrt_tab[256]; 00058 00059 static inline av_const unsigned int ff_sqrt(unsigned int a) 00060 { 00061 unsigned int b; 00062 00063 if (a < 255) return (ff_sqrt_tab[a + 1] - 1) >> 4; 00064 else if (a < (1 << 12)) b = ff_sqrt_tab[a >> 4] >> 2; 00065 #if !CONFIG_SMALL 00066 else if (a < (1 << 14)) b = ff_sqrt_tab[a >> 6] >> 1; 00067 else if (a < (1 << 16)) b = ff_sqrt_tab[a >> 8] ; 00068 #endif 00069 else { 00070 int s = av_log2_16bit(a >> 16) >> 1; 00071 unsigned int c = a >> (s + 2); 00072 b = ff_sqrt_tab[c >> (s + 8)]; 00073 b = FASTDIV(c,b) + (b << s); 00074 } 00075 00076 return b - (a < b * b); 00077 } 00078 00079 #endif /* AVUTIL_INTMATH_H */