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Diffstat (limited to 'libavutil/softfloat.h')
| -rw-r--r-- | libavutil/softfloat.h | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/libavutil/softfloat.h b/libavutil/softfloat.h new file mode 100644 index 0000000000..8647e6a4fc --- /dev/null +++ b/libavutil/softfloat.h @@ -0,0 +1,132 @@ +/* + * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef AVUTIL_SOFTFLOAT_H +#define AVUTIL_SOFTFLOAT_H + +#include <stdint.h> +#include "common.h" + +#include "avassert.h" + +#define MIN_EXP -126 +#define MAX_EXP 126 +#define ONE_BITS 29 + +typedef struct SoftFloat{ + int32_t exp; + int32_t mant; +}SoftFloat; + +static av_const SoftFloat av_normalize_sf(SoftFloat a){ + if(a.mant){ +#if 1 + while((a.mant + 0x20000000U)<0x40000000U){ + a.mant += a.mant; + a.exp -= 1; + } +#else + int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1)); + a.exp -= s; + a.mant <<= s; +#endif + if(a.exp < MIN_EXP){ + a.exp = MIN_EXP; + a.mant= 0; + } + }else{ + a.exp= MIN_EXP; + } + return a; +} + +static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){ +#if 1 + if((int32_t)(a.mant + 0x40000000U) < 0){ + a.exp++; + a.mant>>=1; + } + av_assert2(a.mant < 0x40000000 && a.mant > -0x40000000); + return a; +#elif 1 + int t= a.mant + 0x40000000 < 0; + return (SoftFloat){a.exp+t, a.mant>>t}; +#else + int t= (a.mant + 0x40000000U)>>31; + return (SoftFloat){a.exp+t, a.mant>>t}; +#endif +} + +/** + * @return Will not be more denormalized than a+b. So if either input is + * normalized, then the output will not be worse then the other input. + * If both are normalized, then the output will be normalized. + */ +static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ + a.exp += b.exp; + av_assert2((int32_t)((a.mant * (int64_t)b.mant) >> ONE_BITS) == (a.mant * (int64_t)b.mant) >> ONE_BITS); + a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS; + return av_normalize1_sf(a); +} + +/** + * b has to be normalized and not zero. + * @return Will not be more denormalized than a. + */ +static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){ + a.exp -= b.exp+1; + a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant; + return av_normalize1_sf(a); +} + +static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){ + int t= a.exp - b.exp; + if(t<0) return (a.mant >> (-t)) - b.mant ; + else return a.mant - (b.mant >> t); +} + +static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ + int t= a.exp - b.exp; + if (t <-31) return b; + else if (t < 0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); + else if (t < 32) return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); + else return a; +} + +static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){ + return av_add_sf(a, (SoftFloat){b.exp, -b.mant}); +} + +//FIXME sqrt, log, exp, pow, sin, cos + +static inline av_const SoftFloat av_int2sf(int v, int frac_bits){ + return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v}); +} + +/** + * Rounding is to -inf. + */ +static inline av_const int av_sf2int(SoftFloat v, int frac_bits){ + v.exp += frac_bits - ONE_BITS; + if(v.exp >= 0) return v.mant << v.exp ; + else return v.mant >>(-v.exp); +} + +#endif /* AVUTIL_SOFTFLOAT_H */ |