POK
ilogbf.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_ilogbf.c -- float version of s_ilogb.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 int
38 ilogbf(float x)
39 {
40  int32_t hx,ix;
41 
42  GET_FLOAT_WORD(hx,x);
43  hx &= 0x7fffffff;
44  if(hx<0x00800000) {
45  if(hx==0)
46  return 0x80000001; /* ilogb(0) = 0x80000001 */
47  else /* subnormal x */
48  for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1;
49  return ix;
50  }
51  else if (hx<0x7f800000) return (hx>>23)-127;
52  else return 0x7fffffff;
53 }
54 
55 #endif
56