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git-svn-id: http://svn2.nishi.boats/svn/milsko/trunk@557 b9cfdab3-6d41-4d17-bbe4-086880011989
66 lines
1.6 KiB
C
66 lines
1.6 KiB
C
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/* @(#)e_remainder.c 1.3 95/01/18 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/* __fdlibm_remainder(x,p)
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* Return :
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* returns x REM p = x - [x/p]*p as if in infinite
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* precise arithmetic, where [x/p] is the (infinite bit)
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* integer nearest x/p (in half way case choose the even one).
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* Method :
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* Based on fmod() return x-[x/p]chopped*p exactlp.
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*/
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#include "math.h"
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static const double zero = 0.0;
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double __fdlibm_remainder(double x, double p) {
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int hx, hp;
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unsigned sx, lx, lp;
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double p_half;
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hx = __HI(x); /* high word of x */
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lx = __LO(x); /* low word of x */
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hp = __HI(p); /* high word of p */
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lp = __LO(p); /* low word of p */
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sx = hx & 0x80000000;
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hp &= 0x7fffffff;
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hx &= 0x7fffffff;
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/* purge off exception values */
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if((hp | lp) == 0) return (x * p) / (x * p); /* p = 0 */
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if((hx >= 0x7ff00000) || /* x not finite */
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((hp >= 0x7ff00000) && /* p is NaN */
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(((hp - 0x7ff00000) | lp) != 0)))
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return (x * p) / (x * p);
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if(hp <= 0x7fdfffff) x = __fdlibm_fmod(x, p + p); /* now x < 2p */
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if(((hx - hp) | (lx - lp)) == 0) return zero * x;
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x = fabs(x);
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p = fabs(p);
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if(hp < 0x00200000) {
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if(x + x > p) {
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x -= p;
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if(x + x >= p) x -= p;
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}
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} else {
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p_half = 0.5 * p;
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if(x > p_half) {
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x -= p;
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if(x >= p_half) x -= p;
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}
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}
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__HI(x) ^= sx;
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return x;
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}
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