1 /* @(#)s_nextafter.c 5.1 93/09/24 */ 2 /* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunPro, 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 /* IEEE functions 14 * nextafterl(x,y) 15 * return the next machine floating-point number of x in the 16 * direction toward y. 17 * Special cases: 18 */ 19 20 #include <math.h> 21 22 #include "math_private.h" 23 24 long double 25 nextafterl(long double x, long double y) 26 { 27 int64_t hx,hy,ix,iy; 28 u_int64_t lx,ly; 29 30 GET_LDOUBLE_WORDS64(hx,lx,x); 31 GET_LDOUBLE_WORDS64(hy,ly,y); 32 ix = hx&0x7fffffffffffffffLL; /* |x| */ 33 iy = hy&0x7fffffffffffffffLL; /* |y| */ 34 35 if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) || /* x is nan */ 36 ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0)) /* y is nan */ 37 return x+y; 38 if(x==y) return y; /* x=y, return y */ 39 if((ix|lx)==0) { /* x == 0 */ 40 volatile long double u; 41 SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */ 42 u = x; 43 u = u * u; /* raise underflow flag */ 44 return x; 45 } 46 if(hx>=0) { /* x > 0 */ 47 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ 48 if(lx==0) hx--; 49 lx--; 50 } else { /* x < y, x += ulp */ 51 lx++; 52 if(lx==0) hx++; 53 } 54 } else { /* x < 0 */ 55 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ 56 if(lx==0) hx--; 57 lx--; 58 } else { /* x > y, x += ulp */ 59 lx++; 60 if(lx==0) hx++; 61 } 62 } 63 hy = hx&0x7fff000000000000LL; 64 if(hy==0x7fff000000000000LL) return x+x;/* overflow */ 65 if(hy==0) { 66 volatile long double u = x*x; /* underflow */ 67 } 68 SET_LDOUBLE_WORDS64(x,hx,lx); 69 return x; 70 } 71 72 __strong_alias(nexttowardl, nextafterl); 73