1/* s_logbf.c -- float version of s_logb.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__FBSDID("$FreeBSD$");
18
19#include "math.h"
20#include "math_private.h"
21
22static const float
23two25 = 3.355443200e+07;		/* 0x4c000000 */
24
25float
26logbf(float x)
27{
28	int32_t ix;
29	GET_FLOAT_WORD(ix,x);
30	ix &= 0x7fffffff;			/* high |x| */
31	if(ix==0) return (float)-1.0/fabsf(x);
32	if(ix>=0x7f800000) return x*x;
33	if(ix<0x00800000) {
34		x *= two25;		 /* convert subnormal x to normal */
35		GET_FLOAT_WORD(ix,x);
36		ix &= 0x7fffffff;
37		return (float) ((ix>>23)-127-25);
38	} else
39		return (float) ((ix>>23)-127);
40}
41