1/* s_ilogbf.c -- float version of s_ilogb.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#if defined(LIBM_SCCS) && !defined(lint)
17static char rcsid[] = "$NetBSD: s_ilogbf.c,v 1.4 1995/05/10 20:47:31 jtc Exp $";
18#endif
19
20#include <limits.h>
21#include <math.h>
22#include <math_private.h>
23
24int __ieee754_ilogbf(float x)
25{
26 int32_t hx,ix;
27
28 GET_FLOAT_WORD(hx,x);
29 hx &= 0x7fffffff;
30 if(hx<0x00800000) {
31 if(hx==0)
32 return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */
33 else /* subnormal x */
34 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
35 return ix;
36 }
37 else if (hx<0x7f800000) return (hx>>23)-127;
38 else if (FP_ILOGBNAN != INT_MAX) {
39 /* ISO C99 requires ilogbf(+-Inf) == INT_MAX. */
40 if (hx==0x7f800000)
41 return INT_MAX;
42 }
43 return FP_ILOGBNAN;
44}
45