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90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
/* @(#)s_nextafter.c 5.1 93/09/24 */
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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 SunPro, 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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/* IEEE functions
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* nextafterl(x,y)
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* return the next machine floating-point number of x in the
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* direction toward y.
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* Special cases:
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*/
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#include <openlibm.h>
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#include "math_private.h"
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long double
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nextafterl(long double x, long double y)
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{
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int32_t hx,hy,ix,iy;
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u_int32_t lx,ly,esx,esy;
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GET_LDOUBLE_WORDS(esx,hx,lx,x);
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GET_LDOUBLE_WORDS(esy,hy,ly,y);
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ix = esx&0x7fff; /* |x| */
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iy = esy&0x7fff; /* |y| */
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if (((ix==0x7fff)&&((hx&0x7fffffff|lx)!=0)) || /* x is nan */
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((iy==0x7fff)&&((hy&0x7fffffff|ly)!=0))) /* y is nan */
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return x+y;
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if(x==y) return y; /* x=y, return y */
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if((ix|hx|lx)==0) { /* x == 0 */
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volatile long double u;
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SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */
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u = x;
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u = u * u; /* raise underflow flag */
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return x;
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}
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if(esx<0x8000) { /* x > 0 */
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if(ix>iy||((ix==iy) && (hx>hy||((hx==hy)&&(lx>ly))))) {
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/* x > y, x -= ulp */
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if(lx==0) {
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if ((hx&0x7fffffff)==0) esx -= 1;
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hx = (hx - 1) | (hx & 0x80000000);
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}
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lx -= 1;
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} else { /* x < y, x += ulp */
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lx += 1;
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if(lx==0) {
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hx = (hx + 1) | (hx & 0x80000000);
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if ((hx&0x7fffffff)==0) esx += 1;
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}
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}
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} else { /* x < 0 */
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if(esy>=0||(ix>iy||((ix==iy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){
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/* x < y, x -= ulp */
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if(lx==0) {
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if ((hx&0x7fffffff)==0) esx -= 1;
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hx = (hx - 1) | (hx & 0x80000000);
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}
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lx -= 1;
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} else { /* x > y, x += ulp */
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lx += 1;
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if(lx==0) {
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hx = (hx + 1) | (hx & 0x80000000);
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if ((hx&0x7fffffff)==0) esx += 1;
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}
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}
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}
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esy = esx&0x7fff;
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if(esy==0x7fff) return x+x; /* overflow */
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if(esy==0) {
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volatile long double u = x*x; /* underflow */
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if(u==x) {
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SET_LDOUBLE_WORDS(x,esx,hx,lx);
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return x;
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}
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}
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SET_LDOUBLE_WORDS(x,esx,hx,lx);
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return x;
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}
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//__strong_alias(nexttowardl, nextafterl);
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