You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
78 lines
2.0 KiB
78 lines
2.0 KiB
|
|
/* @(#)s_nextafter.c 1.3 95/01/18 */ |
|
/* |
|
* ==================================================== |
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
|
* |
|
* Developed at SunSoft, a Sun Microsystems, Inc. business. |
|
* Permission to use, copy, modify, and distribute this |
|
* software is freely granted, provided that this notice |
|
* is preserved. |
|
* ==================================================== |
|
*/ |
|
|
|
/* IEEE functions |
|
* nextafter(x,y) |
|
* return the next machine floating-point number of x in the |
|
* direction toward y. |
|
* Special cases: |
|
*/ |
|
|
|
#include "fdlibm.h" |
|
|
|
#ifdef __STDC__ |
|
double ieee_nextafter(double x, double y) |
|
#else |
|
double ieee_nextafter(x,y) |
|
double x,y; |
|
#endif |
|
{ |
|
int hx,hy,ix,iy; |
|
unsigned lx,ly; |
|
|
|
hx = __HI(x); /* high word of x */ |
|
lx = __LO(x); /* low word of x */ |
|
hy = __HI(y); /* high word of y */ |
|
ly = __LO(y); /* low word of 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 x; /* x=y, return x */ |
|
if((ix|lx)==0) { /* x == 0 */ |
|
__HI(x) = hy&0x80000000; /* return +-minsubnormal */ |
|
__LO(x) = 1; |
|
y = x*x; |
|
if(y==x) return y; 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 */ |
|
y = x*x; |
|
if(y!=x) { /* raise underflow flag */ |
|
__HI(y) = hx; __LO(y) = lx; |
|
return y; |
|
} |
|
} |
|
__HI(x) = hx; __LO(x) = lx; |
|
return x; |
|
}
|
|
|