1/* s_ilogbf.c -- float version of s_ilogb.c.
2 */
3
4/*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
8 * Developed at SunPro, a Sun Microsystems, Inc. business.
9 * Permission to use, copy, modify, and distribute this
10 * software is freely granted, provided that this notice
11 * is preserved.
12 * ====================================================
13 */
14
15#if defined(LIBM_SCCS) && !defined(lint)
16static char rcsid[] = "$NetBSD: s_ilogbf.c,v 1.4 1995/05/10 20:47:31 jtc Exp $";
17#endif
18
19#include <limits.h>
20#include <math.h>
21#include <math_private.h>
22
23int __ieee754_ilogbf(float x)
24{
25 int32_t hx,ix;
26
27 GET_FLOAT_WORD(hx,x);
28 hx &= 0x7fffffff;
29 if(hx<0x00800000) {
30 if(hx==0)
31 return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */
32 else /* subnormal x */
33 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
34 return ix;
35 }
36 else if (hx<0x7f800000) return (hx>>23)-127;
37 else if (FP_ILOGBNAN != INT_MAX) {
38 /* ISO C99 requires ilogbf(+-Inf) == INT_MAX. */
39 if (hx==0x7f800000)
40 return INT_MAX;
41 }
42 return FP_ILOGBNAN;
43}
44