1*2fe8fb19SBen Gras /* s_logbf.c -- float version of s_logb.c.
2*2fe8fb19SBen Gras * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3*2fe8fb19SBen Gras */
4*2fe8fb19SBen Gras
5*2fe8fb19SBen Gras /*
6*2fe8fb19SBen Gras * ====================================================
7*2fe8fb19SBen Gras * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8*2fe8fb19SBen Gras *
9*2fe8fb19SBen Gras * Developed at SunPro, a Sun Microsystems, Inc. business.
10*2fe8fb19SBen Gras * Permission to use, copy, modify, and distribute this
11*2fe8fb19SBen Gras * software is freely granted, provided that this notice
12*2fe8fb19SBen Gras * is preserved.
13*2fe8fb19SBen Gras * ====================================================
14*2fe8fb19SBen Gras */
15*2fe8fb19SBen Gras
16*2fe8fb19SBen Gras #include <sys/cdefs.h>
17*2fe8fb19SBen Gras #if defined(LIBM_SCCS) && !defined(lint)
18*2fe8fb19SBen Gras __RCSID("$NetBSD: s_logbf.c,v 1.7 2002/05/26 22:01:57 wiz Exp $");
19*2fe8fb19SBen Gras #endif
20*2fe8fb19SBen Gras
21*2fe8fb19SBen Gras #include "math.h"
22*2fe8fb19SBen Gras #include "math_private.h"
23*2fe8fb19SBen Gras
24*2fe8fb19SBen Gras float
logbf(float x)25*2fe8fb19SBen Gras logbf(float x)
26*2fe8fb19SBen Gras {
27*2fe8fb19SBen Gras int32_t ix;
28*2fe8fb19SBen Gras GET_FLOAT_WORD(ix,x);
29*2fe8fb19SBen Gras ix &= 0x7fffffff; /* high |x| */
30*2fe8fb19SBen Gras if(ix==0) return (float)-1.0/fabsf(x);
31*2fe8fb19SBen Gras if(ix>=0x7f800000) return x*x;
32*2fe8fb19SBen Gras if((ix>>=23)==0) /* IEEE 754 logb */
33*2fe8fb19SBen Gras return -126.0;
34*2fe8fb19SBen Gras else
35*2fe8fb19SBen Gras return (float) (ix-127);
36*2fe8fb19SBen Gras }
37