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a2fd60437d
unused currently, but might come in handy for some fpu-less cpus Originally committed as revision 5955 to svn://svn.ffmpeg.org/ffmpeg/trunk
104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
//copyright Michael Niedermayer 2006 license:LGPL
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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 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 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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*
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* @return will not be more denormalized then a+b, so if either input is
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* normalized then the output wont 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 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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*
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* b has to be normalized and not zero
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* @return will not be more denormalized then a
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*/
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static 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 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 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 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 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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*
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* rounding is to -inf
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*/
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static inline 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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