| |
| /* @(#)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" |
| |
| #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; |
| } |
| |
| #endif /* defined(_DOUBLE_IS_32BITS) */ |
