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.
46 lines
1.1 KiB
46 lines
1.1 KiB
|
|
/* @(#)s_ilogb.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_ilogb(double x) |
|
* return the binary exponent of non-zero x |
|
* ieee_ilogb(0) = 0x80000001 |
|
* ieee_ilogb(inf/NaN) = 0x7fffffff (no signal is raised) |
|
*/ |
|
|
|
#include "fdlibm.h" |
|
|
|
#ifdef __STDC__ |
|
int ieee_ilogb(double x) |
|
#else |
|
int ieee_ilogb(x) |
|
double x; |
|
#endif |
|
{ |
|
int hx,lx,ix; |
|
|
|
hx = (__HI(x))&0x7fffffff; /* high word of x */ |
|
if(hx<0x00100000) { |
|
lx = __LO(x); |
|
if((hx|lx)==0) |
|
return 0x80000001; /* ieee_ilogb(0) = 0x80000001 */ |
|
else /* subnormal x */ |
|
if(hx==0) { |
|
for (ix = -1043; lx>0; lx<<=1) ix -=1; |
|
} else { |
|
for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; |
|
} |
|
return ix; |
|
} |
|
else if (hx<0x7ff00000) return (hx>>20)-1023; |
|
else return 0x7fffffff; |
|
}
|
|
|