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 #include <math.h> 14 15 #include "math_private.h" 16 17 float 18 nexttowardf(float x, long double y) 19 { 20 int32_t hx,ix; 21 int64_t hy,iy; 22 u_int64_t ly; 23 24 GET_FLOAT_WORD(hx,x); 25 GET_LDOUBLE_WORDS64(hy,ly,y); 26 ix = hx&0x7fffffff; /* |x| */ 27 iy = hy&0x7fffffffffffffffLL; /* |y| */ 28 29 if((ix>0x7f800000) || /* x is nan */ 30 ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0)) 31 /* y is nan */ 32 return x+y; 33 if((long double) x==y) return y; /* x=y, return y */ 34 if(ix==0) { /* x == 0 */ 35 volatile float u; 36 SET_FLOAT_WORD(x,(u_int32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/ 37 u = x; 38 u = u * u; /* raise underflow flag */ 39 return x; 40 } 41 if(hx>=0) { /* x > 0 */ 42 if(hy<0||(ix>>23)>(iy>>48)-0x3f80 43 || ((ix>>23)==(iy>>48)-0x3f80 44 && (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x > y, x -= ulp */ 45 hx -= 1; 46 } else { /* x < y, x += ulp */ 47 hx += 1; 48 } 49 } else { /* x < 0 */ 50 if(hy>=0||(ix>>23)>(iy>>48)-0x3f80 51 || ((ix>>23)==(iy>>48)-0x3f80 52 && (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x < y, x -= ulp */ 53 hx -= 1; 54 } else { /* x > y, x += ulp */ 55 hx += 1; 56 } 57 } 58 hy = hx&0x7f800000; 59 if(hy>=0x7f800000) return x+x; /* overflow */ 60 if(hy<0x00800000) { 61 volatile float u = x*x; /* underflow */ 62 } 63 SET_FLOAT_WORD(x,hx); 64 return x; 65 } 66