Libav
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00001 /* 00002 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 00003 * 00004 * This file is part of FFmpeg. 00005 * 00006 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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_SOFTFLOAT_H 00022 #define AVUTIL_SOFTFLOAT_H 00023 00024 #include <stdint.h> 00025 #include "common.h" 00026 00027 #define MIN_EXP -126 00028 #define MAX_EXP 126 00029 #define ONE_BITS 29 00030 00031 typedef struct SoftFloat{ 00032 int32_t exp; 00033 int32_t mant; 00034 }SoftFloat; 00035 00036 static av_const SoftFloat av_normalize_sf(SoftFloat a){ 00037 if(a.mant){ 00038 #if 1 00039 while((a.mant + 0x20000000U)<0x40000000U){ 00040 a.mant += a.mant; 00041 a.exp -= 1; 00042 } 00043 #else 00044 int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1)); 00045 a.exp -= s; 00046 a.mant <<= s; 00047 #endif 00048 if(a.exp < MIN_EXP){ 00049 a.exp = MIN_EXP; 00050 a.mant= 0; 00051 } 00052 }else{ 00053 a.exp= MIN_EXP; 00054 } 00055 return a; 00056 } 00057 00058 static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){ 00059 #if 1 00060 if(a.mant + 0x40000000 < 0){ 00061 a.exp++; 00062 a.mant>>=1; 00063 } 00064 return a; 00065 #elif 1 00066 int t= a.mant + 0x40000000 < 0; 00067 return (SoftFloat){a.exp+t, a.mant>>t}; 00068 #else 00069 int t= (a.mant + 0x40000000U)>>31; 00070 return (SoftFloat){a.exp+t, a.mant>>t}; 00071 #endif 00072 } 00073 00079 static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ 00080 a.exp += b.exp; 00081 a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS; 00082 return av_normalize1_sf(a); 00083 } 00084 00089 static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){ 00090 a.exp -= b.exp+1; 00091 a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant; 00092 return av_normalize1_sf(a); 00093 } 00094 00095 static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){ 00096 int t= a.exp - b.exp; 00097 if(t<0) return (a.mant >> (-t)) - b.mant ; 00098 else return a.mant - (b.mant >> t); 00099 } 00100 00101 static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ 00102 int t= a.exp - b.exp; 00103 if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); 00104 else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); 00105 } 00106 00107 static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){ 00108 return av_add_sf(a, (SoftFloat){b.exp, -b.mant}); 00109 } 00110 00111 //FIXME sqrt, log, exp, pow, sin, cos 00112 00113 static inline av_const SoftFloat av_int2sf(int v, int frac_bits){ 00114 return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v}); 00115 } 00116 00120 static inline av_const int av_sf2int(SoftFloat v, int frac_bits){ 00121 v.exp += frac_bits - ONE_BITS; 00122 if(v.exp >= 0) return v.mant << v.exp ; 00123 else return v.mant >>(-v.exp); 00124 } 00125 00126 #endif /* AVUTIL_SOFTFLOAT_H */