| /* @(#)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. |
| * ==================================================== |
| */ |
| |
| #include <sys/cdefs.h> |
| __FBSDID("$FreeBSD$"); |
| |
| /* IEEE functions |
| * nextafter(x,y) |
| * return the next machine floating-point number of x in the |
| * direction toward y. |
| * Special cases: |
| */ |
| |
| #include <float.h> |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| double |
| nextafter(double x, double y) |
| { |
| volatile double t; |
| 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 */ |
| INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */ |
| t = x*x; |
| if(t==x) return t; else return x; /* raise underflow flag */ |
| } |
| 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) return x+x; /* overflow */ |
| if(hy<0x00100000) { /* underflow */ |
| t = x*x; |
| if(t!=x) { /* raise underflow flag */ |
| INSERT_WORDS(y,hx,lx); |
| return y; |
| } |
| } |
| INSERT_WORDS(x,hx,lx); |
| return x; |
| } |
| |
| #if (LDBL_MANT_DIG == 53) |
| __weak_reference(nextafter, nexttoward); |
| __weak_reference(nextafter, nexttowardl); |
| __weak_reference(nextafter, nextafterl); |
| #endif |
