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 int32_t hx,hy,ix,iy; 28 u_int32_t lx,ly; 29 int32_t esx,esy; 30 31 GET_LDOUBLE_WORDS(esx,hx,lx,x); 32 GET_LDOUBLE_WORDS(esy,hy,ly,y); 33 ix = esx&0x7fff; /* |x| */ 34 iy = esy&0x7fff; /* |y| */ 35 36 if (((ix==0x7fff)&&(((hx&0x7fffffff)|lx)!=0)) || /* x is nan */ 37 ((iy==0x7fff)&&(((hy&0x7fffffff)|ly)!=0))) /* y is nan */ 38 return x+y; 39 if(x==y) return y; /* x=y, return y */ 40 if((ix|hx|lx)==0) { /* x == 0 */ 41 volatile long double u; 42 SET_LDOUBLE_WORDS(x,esy&0x8000,0,1);/* return +-minsubnormal */ 43 u = x; 44 u = u * u; /* raise underflow flag */ 45 return x; 46 } 47 if(esx>=0) { /* x > 0 */ 48 if(esx>esy||((esx==esy) && (hx>hy||((hx==hy)&&(lx>ly))))) { 49 /* x > y, x -= ulp */ 50 if(lx==0) { 51 if ((hx&0x7fffffff)==0) esx -= 1; 52 hx = (hx - 1) | (hx & 0x80000000); 53 } 54 lx -= 1; 55 } else { /* x < y, x += ulp */ 56 lx += 1; 57 if(lx==0) { 58 hx = (hx + 1) | (hx & 0x80000000); 59 if ((hx&0x7fffffff)==0) esx += 1; 60 } 61 } 62 } else { /* x < 0 */ 63 if(esy>=0||(esx>esy||((esx==esy)&&(hx>hy||((hx==hy)&&(lx>ly)))))){ 64 /* x < y, x -= ulp */ 65 if(lx==0) { 66 if ((hx&0x7fffffff)==0) esx -= 1; 67 hx = (hx - 1) | (hx & 0x80000000); 68 } 69 lx -= 1; 70 } else { /* x > y, x += ulp */ 71 lx += 1; 72 if(lx==0) { 73 hx = (hx + 1) | (hx & 0x80000000); 74 if ((hx&0x7fffffff)==0) esx += 1; 75 } 76 } 77 } 78 esy = esx&0x7fff; 79 if(esy==0x7fff) return x+x; /* overflow */ 80 if(esy==0) { 81 volatile long double u = x*x; /* underflow */ 82 if(u==x) { 83 SET_LDOUBLE_WORDS(x,esx,hx,lx); 84 return x; 85 } 86 } 87 SET_LDOUBLE_WORDS(x,esx,hx,lx); 88 return x; 89 } 90 DEF_STD(nextafterl); 91 MAKE_UNUSED_CLONE(nexttowardl, nextafterl); 92