POK
log2.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 /* @(#)w_log10.c 5.1 93/09/24 */
18 /*
19  * ====================================================
20  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
21  *
22  * Developed at SunPro, a Sun Microsystems, Inc. business.
23  * Permission to use, copy, modify, and distribute this
24  * software is freely granted, provided that this notice
25  * is preserved.
26  * ====================================================
27  */
28 
29 #ifdef POK_NEEDS_LIBMATH
30 
31 /*
32  * wrapper log2(X)
33  */
34 
35 #include <libm.h>
36 #include "math_private.h"
37 
38 
39 double
40 log2(double x) /* wrapper log10 */
41 {
42 #ifdef _IEEE_LIBM
43  return __ieee754_log2(x);
44 #else
45  double z;
46  z = __ieee754_log2(x);
47  if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
48  if(x<=0.0) {
49  if(x==0.0)
50  return __kernel_standard(x,x,48); /* log2(0) */
51  else
52  return __kernel_standard(x,x,49); /* log2(x<0) */
53  } else
54  return z;
55 #endif
56 }
57 
58 #endif