1 /*
2 * ====================================================
3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
4 *
5 * Developed at SunPro, a Sun Microsystems, Inc. business.
6 * Permission to use, copy, modify, and distribute this
7 * software is freely granted, provided that this notice
8 * is preserved.
9 * ====================================================
10 */
11
12 /* ilogb(double x)
13 * return the binary exponent of non-zero x
14 * ilogb(0) = FP_ILOGB0
15 * ilogb(NaN) = FP_ILOGBNAN (no signal is raised)
16 * ilogb(inf) = INT_MAX (no signal is raised)
17 */
18
19 #include <limits.h>
20
21 #include "math.h"
22 #include "math_private.h"
23
24 int
ilogb(double x)25 ilogb(double x)
26 {
27 int32_t hx, ix, lx;
28
29 EXTRACT_WORDS(hx,lx,x);
30 hx &= 0x7fffffff;
31 if(hx<0x00100000) {
32 if((hx|lx)==0)
33 return FP_ILOGB0;
34 else
35 ix = subnormal_ilogb(hx, lx);
36 return ix;
37 }
38 else if (hx<0x7ff00000) return (hx>>20)-1023;
39 else if (hx>0x7ff00000 || lx!=0) return FP_ILOGBNAN;
40 else return INT_MAX;
41 }
42