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