/* @(#)s_nextafter.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. * ==================================================== */ #ifndef lint static char rcsid[] = "$Id: s_nextafter.c,v 1.1.1.1 1994/08/19 09:39:52 jkh Exp $"; #endif /* IEEE functions * nextafter(x,y) * return the next machine floating-point number of x in the * direction toward y. * Special cases: */ #include "math.h" #include "math_private.h" #ifdef __STDC__ double nextafter(double x, double y) #else double nextafter(x,y) double x,y; #endif { int32_t hx,hy,ix,iy; u_int32_t lx,ly; EXTRACT_WORDS(hx,lx,x); EXTRACT_WORDS(hy,ly,y); ix = hx&0x7fffffff; /* |x| */ iy = hy&0x7fffffff; /* |y| */ if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */ ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */ return x+y; if(x==y) return x; /* x=y, return x */ if((ix|lx)==0) { /* x == 0 */ INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */ y = x*x; if(y==x) return y; else return x; /* raise underflow flag */ } if(hx>=0) { /* x > 0 */ if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ if(lx==0) hx -= 1; lx -= 1; } else { /* x < y, x += ulp */ lx += 1; if(lx==0) hx += 1; } } else { /* x < 0 */ if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ if(lx==0) hx -= 1; lx -= 1; } else { /* x > y, x += ulp */ lx += 1; if(lx==0) hx += 1; } } hy = hx&0x7ff00000; if(hy>=0x7ff00000) return x+x; /* overflow */ if(hy<0x00100000) { /* underflow */ y = x*x; if(y!=x) { /* raise underflow flag */ INSERT_WORDS(y,hx,lx); return y; } } INSERT_WORDS(x,hx,lx); return x; }