POK
logbf.c
1 /*
2  * POK header
3  *
4  * The following file is a part of the POK project. Any modification should
5  * made according to the POK licence. You CANNOT use this file or a part of
6  * this file is this part of a file for your own project
7  *
8  * For more information on the POK licence, please see our LICENCE FILE
9  *
10  * Please follow the coding guidelines described in doc/CODING_GUIDELINES
11  *
12  * Copyright (c) 2007-2009 POK team
13  *
14  * Created by julien on Fri Jan 30 14:41:34 2009
15  */
16 
17 /* s_logbf.c -- float version of s_logb.c.
18  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
19  */
20 
21 /*
22  * ====================================================
23  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
24  *
25  * Developed at SunPro, a Sun Microsystems, Inc. business.
26  * Permission to use, copy, modify, and distribute this
27  * software is freely granted, provided that this notice
28  * is preserved.
29  * ====================================================
30  */
31 
32 #ifdef POK_NEEDS_LIBMATH
33 
34 #include <libm.h>
35 #include "math_private.h"
36 
37 float
38 logbf(float x)
39 {
40  int32_t ix;
41  GET_FLOAT_WORD(ix,x);
42  ix &= 0x7fffffff; /* high |x| */
43  if(ix==0) return (float)-1.0/fabsf(x);
44  if(ix>=0x7f800000) return x*x;
45  if((ix>>=23)==0) /* IEEE 754 logb */
46  return -126.0;
47  else
48  return (float) (ix-127);
49 }
50 
51 #endif