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 #ifndef lint
17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_logbf.c,v 1.8 2005/12/03 11:57:19 bde Exp $";
18 #endif
19
20 #include "math.h"
21 #include "math_private.h"
22
23 static const float
24 two25 = 3.355443200e+07; /* 0x4c000000 */
25
26 float
logbf(float x)27 logbf(float x)
28 {
29 int32_t ix;
30 GET_FLOAT_WORD(ix,x);
31 ix &= 0x7fffffff; /* high |x| */
32 if(ix==0) return (float)-1.0/fabsf(x);
33 if(ix>=0x7f800000) return x*x;
34 if(ix<0x00800000) {
35 x *= two25; /* convert subnormal x to normal */
36 GET_FLOAT_WORD(ix,x);
37 ix &= 0x7fffffff;
38 return (float) ((ix>>23)-127-25);
39 } else
40 return (float) ((ix>>23)-127);
41 }
42