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 #include <sys/cdefs.h>
17 #if defined(LIBM_SCCS) && !defined(lint)
18 __RCSID("$NetBSD: s_ilogbf.c,v 1.8 2013/02/09 22:56:00 matt Exp $");
19 #endif
20
21 #include "math.h"
22 #include "math_private.h"
23
24 int
ilogbf(float x)25 ilogbf(float x)
26 {
27 int32_t hx,ix;
28
29 GET_FLOAT_WORD(hx,x);
30 hx &= 0x7fffffff;
31 if(hx<0x00800000) {
32 if(hx==0)
33 return FP_ILOGB0; /* ilogb(0) = 0x80000001 */
34 else /* subnormal x */
35 for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
36 return ix;
37 }
38 else if (hx<0x7f800000) return (hx>>23)-127;
39 else return FP_ILOGBNAN; /* inf too */
40 }
41