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| 2 | /* @(#)e_remainder.c 5.1 93/09/24 */
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| 3 | /*
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| 4 | * ====================================================
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| 5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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| 6 | *
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| 7 | * Developed at SunPro, a Sun Microsystems, Inc. business.
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| 8 | * Permission to use, copy, modify, and distribute this
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| 9 | * software is freely granted, provided that this notice
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| 10 | * is preserved.
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| 11 | * ====================================================
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| 12 | */
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| 13 |
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| 14 | /* __ieee754_remainder(x,p)
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| 15 | * Return :
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| 16 | * returns x REM p = x - [x/p]*p as if in infinite
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| 17 | * precise arithmetic, where [x/p] is the (infinite bit)
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| 18 | * integer nearest x/p (in half way case choose the even one).
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| 19 | * Method :
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| 20 | * Based on fmod() return x-[x/p]chopped*p exactlp.
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| 21 | */
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| 22 |
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| 23 | #include "fdlibm.h"
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| 24 |
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| 25 | #ifndef _DOUBLE_IS_32BITS
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| 26 |
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| 27 | #ifdef __STDC__
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| 28 | static const double zero = 0.0;
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| 29 | #else
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| 30 | static double zero = 0.0;
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| 31 | #endif
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| 32 |
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| 33 |
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| 34 | #ifdef __STDC__
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| 35 | double __ieee754_remainder(double x, double p)
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| 36 | #else
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| 37 | double __ieee754_remainder(x,p)
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| 38 | double x,p;
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| 39 | #endif
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| 40 | {
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| 41 | int32_t hx,hp;
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| 42 | uint32_t sx,lx,lp;
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| 43 | double p_half;
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| 44 |
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| 45 | EXTRACT_WORDS(hx,lx,x);
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| 46 | EXTRACT_WORDS(hp,lp,p);
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| 47 | sx = hx&0x80000000;
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| 48 | hp &= 0x7fffffff;
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| 49 | hx &= 0x7fffffff;
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| 50 |
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| 51 | /* purge off exception values */
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| 52 | if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */
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| 53 | if((hx>=0x7ff00000)|| /* x not finite */
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| 54 | ((hp>=0x7ff00000)&& /* p is NaN */
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| 55 | (((hp-0x7ff00000)|lp)!=0)))
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| 56 | return (x*p)/(x*p);
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| 57 |
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| 58 |
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| 59 | if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */
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| 60 | if (((hx-hp)|(lx-lp))==0) return zero*x;
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| 61 | x = fabs(x);
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| 62 | p = fabs(p);
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| 63 | if (hp<0x00200000) {
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| 64 | if(x+x>p) {
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| 65 | x-=p;
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| 66 | if(x+x>=p) x -= p;
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| 67 | }
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| 68 | } else {
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| 69 | p_half = 0.5*p;
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| 70 | if(x>p_half) {
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| 71 | x-=p;
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| 72 | if(x>=p_half) x -= p;
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| 73 | }
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| 74 | }
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| 75 | GET_HIGH_WORD(hx,x);
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| 76 | SET_HIGH_WORD(x,hx^sx);
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| 77 | return x;
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| 78 | }
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| 79 |
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| 80 | #endif /* defined(_DOUBLE_IS_32BITS) */
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