1 2 /* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunSoft, a Sun Microsystems, Inc. business. 7 * Permission to use, copy, modify, and distribute this 8 * software is freely granted, provided that this notice 9 * is preserved. 10 * ==================================================== 11 */ 12 13 #include <sys/cdefs.h> 14 /* remainder(x,p) 15 * Return : 16 * returns x REM p = x - [x/p]*p as if in infinite 17 * precise arithmetic, where [x/p] is the (infinite bit) 18 * integer nearest x/p (in half way case choose the even one). 19 * Method : 20 * Based on fmod() return x-[x/p]chopped*p exactlp. 21 */ 22 23 #include <float.h> 24 25 #include "math.h" 26 #include "math_private.h" 27 28 static const double zero = 0.0; 29 30 31 double 32 remainder(double x, double p) 33 { 34 int32_t hx,hp; 35 u_int32_t sx,lx,lp; 36 double p_half; 37 38 EXTRACT_WORDS(hx,lx,x); 39 EXTRACT_WORDS(hp,lp,p); 40 sx = hx&0x80000000; 41 hp &= 0x7fffffff; 42 hx &= 0x7fffffff; 43 44 /* purge off exception values */ 45 if(((hp|lp)==0)|| /* p = 0 */ 46 (hx>=0x7ff00000)|| /* x not finite */ 47 ((hp>=0x7ff00000)&& /* p is NaN */ 48 (((hp-0x7ff00000)|lp)!=0))) 49 return nan_mix_op(x, p, *)/nan_mix_op(x, p, *); 50 51 52 if (hp<=0x7fdfffff) x = fmod(x,p+p); /* now x < 2p */ 53 if (((hx-hp)|(lx-lp))==0) return zero*x; 54 x = fabs(x); 55 p = fabs(p); 56 if (hp<0x00200000) { 57 if(x+x>p) { 58 x-=p; 59 if(x+x>=p) x -= p; 60 } 61 } else { 62 p_half = 0.5*p; 63 if(x>p_half) { 64 x-=p; 65 if(x>=p_half) x -= p; 66 } 67 } 68 GET_HIGH_WORD(hx,x); 69 if ((hx&0x7fffffff)==0) hx = 0; 70 SET_HIGH_WORD(x,hx^sx); 71 return x; 72 } 73 74 #if LDBL_MANT_DIG == 53 75 __weak_reference(remainder, remainderl); 76 #endif 77