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126 lines
3.5 KiB
126 lines
3.5 KiB
/* |
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* Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#ifndef AVUTIL_SOFTFLOAT_H |
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#define AVUTIL_SOFTFLOAT_H |
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#include <stdint.h> |
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#include "common.h" |
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#define MIN_EXP -126 |
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#define MAX_EXP 126 |
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#define ONE_BITS 29 |
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typedef struct SoftFloat{ |
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int32_t exp; |
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int32_t mant; |
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}SoftFloat; |
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static av_const SoftFloat av_normalize_sf(SoftFloat a){ |
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if(a.mant){ |
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#if 1 |
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while((a.mant + 0x20000000U)<0x40000000U){ |
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a.mant += a.mant; |
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a.exp -= 1; |
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} |
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#else |
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int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1)); |
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a.exp -= s; |
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a.mant <<= s; |
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#endif |
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if(a.exp < MIN_EXP){ |
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a.exp = MIN_EXP; |
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a.mant= 0; |
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} |
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}else{ |
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a.exp= MIN_EXP; |
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} |
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return a; |
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} |
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static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){ |
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#if 1 |
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if(a.mant + 0x40000000 < 0){ |
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a.exp++; |
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a.mant>>=1; |
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} |
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return a; |
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#elif 1 |
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int t= a.mant + 0x40000000 < 0; |
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return (SoftFloat){a.exp+t, a.mant>>t}; |
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#else |
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int t= (a.mant + 0x40000000U)>>31; |
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return (SoftFloat){a.exp+t, a.mant>>t}; |
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#endif |
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} |
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/** |
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* @return Will not be more denormalized than a+b. So if either input is |
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* normalized, then the output will not be worse then the other input. |
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* If both are normalized, then the output will be normalized. |
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*/ |
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static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ |
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a.exp += b.exp; |
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a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS; |
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return av_normalize1_sf(a); |
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} |
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/** |
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* b has to be normalized and not zero. |
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* @return Will not be more denormalized than a. |
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*/ |
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static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){ |
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a.exp -= b.exp+1; |
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a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant; |
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return av_normalize1_sf(a); |
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} |
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static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){ |
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int t= a.exp - b.exp; |
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if(t<0) return (a.mant >> (-t)) - b.mant ; |
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else return a.mant - (b.mant >> t); |
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} |
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static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ |
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int t= a.exp - b.exp; |
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if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); |
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else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); |
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} |
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static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){ |
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return av_add_sf(a, (SoftFloat){b.exp, -b.mant}); |
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} |
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//FIXME sqrt, log, exp, pow, sin, cos |
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static inline av_const SoftFloat av_int2sf(int v, int frac_bits){ |
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return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v}); |
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} |
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/** |
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* Rounding is to -inf. |
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*/ |
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static inline av_const int av_sf2int(SoftFloat v, int frac_bits){ |
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v.exp += frac_bits - ONE_BITS; |
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if(v.exp >= 0) return v.mant << v.exp ; |
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else return v.mant >>(-v.exp); |
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} |
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#endif /* AVUTIL_SOFTFLOAT_H */
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