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author | Michael Niedermayer <michaelni@gmx.at> | 2006-08-08 07:58:10 +0000 |
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committer | Michael Niedermayer <michaelni@gmx.at> | 2006-08-08 07:58:10 +0000 |
commit | a2fd60437d0c7cf21a9365024efaa764bddaf3ab (patch) | |
tree | e0e233702894ebff2018cbc1ec9873b239989519 | |
parent | bcfa3e58ee0ec7f8a739867ea66f9acb834e498a (diff) | |
download | ffmpeg-a2fd60437d0c7cf21a9365024efaa764bddaf3ab.tar.gz |
floating point "emulation" code
unused currently, but might come in handy for some fpu-less cpus
Originally committed as revision 5955 to svn://svn.ffmpeg.org/ffmpeg/trunk
-rw-r--r-- | libavutil/softfloat.c | 52 | ||||
-rw-r--r-- | libavutil/softfloat.h | 103 |
2 files changed, 155 insertions, 0 deletions
diff --git a/libavutil/softfloat.c b/libavutil/softfloat.c new file mode 100644 index 0000000000..f47309f26a --- /dev/null +++ b/libavutil/softfloat.c @@ -0,0 +1,52 @@ +#include <inttypes.h> +#include <stdio.h> +#include <assert.h> +#include "softfloat.h" +#include "common.h" +#include "log.h" + +#undef printf + +int main(){ + SoftFloat one= av_int2sf(1, 0); + SoftFloat sf1, sf2; + double d1, d2; + int i, j; +av_log_level = AV_LOG_DEBUG; + + d1= 1; + for(i= 0; i<10; i++){ + d1= 1/(d1+1); + } + printf("test1 double=%d\n", (int)(d1 * (1<<24))); + + sf1= one; + for(i= 0; i<10; i++){ + sf1= av_div_sf(one, av_normalize_sf(av_add_sf(one, sf1))); + } + printf("test1 sf =%d\n", av_sf2int(sf1, 24)); + + + for(i= 0; i<100; i++){ + START_TIMER + d1= i; + d2= i/100.0; + for(j= 0; j<1000; j++){ + d1= (d1+1)*d2; + } + STOP_TIMER("float add mul") + } + printf("test2 double=%d\n", (int)(d1 * (1<<24))); + + for(i= 0; i<100; i++){ + START_TIMER + sf1= av_int2sf(i, 0); + sf2= av_div_sf(av_int2sf(i, 2), av_int2sf(200, 3)); + for(j= 0; j<1000; j++){ + sf1= av_mul_sf(av_add_sf(sf1, one),sf2); + } + STOP_TIMER("softfloat add mul") + } + printf("test2 sf =%d (%d %d)\n", av_sf2int(sf1, 24), sf1.exp, sf1.mant); + return 0; +} diff --git a/libavutil/softfloat.h b/libavutil/softfloat.h new file mode 100644 index 0000000000..6b1831aeba --- /dev/null +++ b/libavutil/softfloat.h @@ -0,0 +1,103 @@ +//copyright Michael Niedermayer 2006 license:LGPL + +#define MIN_EXP -126 +#define MAX_EXP 126 +#define ONE_BITS 29 + +typedef struct SoftFloat{ + int32_t exp; + int32_t mant; +}SoftFloat; + +static 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 SoftFloat av_normalize1_sf(SoftFloat a){ +#if 1 + if(a.mant + 0x40000000 < 0){ + a.exp++; + a.mant>>=1; + } + 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 then a+b, so if either input is + * normalized then the output wont be worse then the other input + * if both are normalized then the output will be normalized + */ +static inline SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ + a.exp += b.exp; + 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 then a + */ +static 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 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 SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ + int t= a.exp - b.exp; + if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); + else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); +} + +static inline 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 SoftFloat av_int2sf(int v, int frac_bits){ + return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v}); +} + +/** + * + * rounding is to -inf + */ +static inline 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); +} |