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 1.10 2016/08/26 08:20:31 christos Exp $");
19 #endif
20
21 #include <math.h>
22 #define __TEST_FENV
23 #include <fenv.h>
24 #ifndef __HAVE_FENV
25 #define feraiseexcept(a)
26 #endif
27 #include "math_private.h"
28
29 int
ilogbf(float x)30 ilogbf(float x)
31 {
32 int32_t hx, ix;
33
34 GET_FLOAT_WORD(hx, x);
35 hx &= 0x7fffffff;
36 if (hx < 0x00800000) {
37 if (hx == 0) {
38 feraiseexcept(FE_INVALID);
39 return FP_ILOGB0; /* ilogb(0) = 0x80000001 */
40 }
41 for (ix = -126, hx <<= 8; hx > 0; hx <<= 1) ix -= 1;
42 return ix;
43 }
44
45 if (hx < 0x7f800000) {
46 return (hx >> 23) - 127;
47 }
48
49 feraiseexcept(FE_INVALID);
50 return isnan(x) ? FP_ILOGBNAN : INT_MAX;
51 }
52