| /* @(#)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. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$NetBSD: s_nextafter.c,v 1.8 1995/05/10 20:47:58 jtc Exp $"; |
| #endif |
| |
| /* IEEE functions |
| * nextafter(x,y) |
| * return the next machine floating-point number of x in the |
| * direction toward y. |
| * Special cases: |
| */ |
| |
| /* Ugly hack so that the aliasing works. */ |
| #define __nexttoward __internal___nexttoward |
| #define nexttoward __internal_nexttoward |
| |
| #include <errno.h> |
| #include <math.h> |
| #include <math_private.h> |
| #include <float.h> |
| |
| double __nextafter(double x, double y) |
| { |
| 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 y; /* x=y, return y */ |
| if((ix|lx)==0) { /* x == 0 */ |
| double u; |
| INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */ |
| u = math_opt_barrier (x); |
| u = u*u; |
| math_force_eval (u); /* raise underflow flag */ |
| return x; |
| } |
| 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) { |
| double u = x+x; /* overflow */ |
| math_force_eval (u); |
| __set_errno (ERANGE); |
| } |
| if(hy<0x00100000) { |
| double u = x*x; /* underflow */ |
| math_force_eval (u); /* raise underflow flag */ |
| __set_errno (ERANGE); |
| } |
| INSERT_WORDS(x,hx,lx); |
| return x; |
| } |
| weak_alias (__nextafter, nextafter) |
| #ifdef NO_LONG_DOUBLE |
| strong_alias (__nextafter, __nextafterl) |
| weak_alias (__nextafter, nextafterl) |
| strong_alias (__nextafter, __nexttowardl) |
| weak_alias (__nexttowardl, nexttowardl) |
| #undef __nexttoward |
| strong_alias (__nextafter, __nexttoward) |
| #undef nexttoward |
| weak_alias (__nextafter, nexttoward) |
| #endif |