0,0 → 1,80 |
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/* @(#)e_remainder.c 5.1 93/09/24 */ |
/* |
* ==================================================== |
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
* |
* Developed at SunPro, a Sun Microsystems, Inc. business. |
* Permission to use, copy, modify, and distribute this |
* software is freely granted, provided that this notice |
* is preserved. |
* ==================================================== |
*/ |
|
/* __ieee754_remainder(x,p) |
* Return : |
* returns x REM p = x - [x/p]*p as if in infinite |
* precise arithmetic, where [x/p] is the (infinite bit) |
* integer nearest x/p (in half way case choose the even one). |
* Method : |
* Based on fmod() return x-[x/p]chopped*p exactlp. |
*/ |
|
#include "fdlibm.h" |
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#ifndef _DOUBLE_IS_32BITS |
|
#ifdef __STDC__ |
static const double zero = 0.0; |
#else |
static double zero = 0.0; |
#endif |
|
|
#ifdef __STDC__ |
double __ieee754_remainder(double x, double p) |
#else |
double __ieee754_remainder(x,p) |
double x,p; |
#endif |
{ |
__int32_t hx,hp; |
__uint32_t sx,lx,lp; |
double p_half; |
|
EXTRACT_WORDS(hx,lx,x); |
EXTRACT_WORDS(hp,lp,p); |
sx = hx&0x80000000; |
hp &= 0x7fffffff; |
hx &= 0x7fffffff; |
|
/* purge off exception values */ |
if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */ |
if((hx>=0x7ff00000)|| /* x not finite */ |
((hp>=0x7ff00000)&& /* p is NaN */ |
(((hp-0x7ff00000)|lp)!=0))) |
return (x*p)/(x*p); |
|
|
if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */ |
if (((hx-hp)|(lx-lp))==0) return zero*x; |
x = fabs(x); |
p = fabs(p); |
if (hp<0x00200000) { |
if(x+x>p) { |
x-=p; |
if(x+x>=p) x -= p; |
} |
} else { |
p_half = 0.5*p; |
if(x>p_half) { |
x-=p; |
if(x>=p_half) x -= p; |
} |
} |
GET_HIGH_WORD(hx,x); |
SET_HIGH_WORD(x,hx^sx); |
return x; |
} |
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#endif /* defined(_DOUBLE_IS_32BITS) */ |