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comparison packages/language/c/libm/current/src/double/portable-api/s_logb.c @ 208:e0c0827131d1 ecos

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Merge from eCos master repository on 2002-05-20-20:11:54-BST
author jlarmour
date Mon, 20 May 2002 22:19:26 +0000
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children d2c90368aeef
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207:74c807ddde34 208:e0c0827131d1
1 //===========================================================================
2 //
3 // s_logb.c
4 //
5 // Part of the standard mathematical function library
6 //
7 //===========================================================================
8 //####ECOSGPLCOPYRIGHTBEGIN####
9 // -------------------------------------------
10 // This file is part of eCos, the Embedded Configurable Operating System.
11 // Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
12 //
13 // eCos is free software; you can redistribute it and/or modify it under
14 // the terms of the GNU General Public License as published by the Free
15 // Software Foundation; either version 2 or (at your option) any later version.
16 //
17 // eCos is distributed in the hope that it will be useful, but WITHOUT ANY
18 // WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
20 // for more details.
21 //
22 // You should have received a copy of the GNU General Public License along
23 // with eCos; if not, write to the Free Software Foundation, Inc.,
24 // 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
25 //
26 // As a special exception, if other files instantiate templates or use macros
27 // or inline functions from this file, or you compile this file and link it
28 // with other works to produce a work based on this file, this file does not
29 // by itself cause the resulting work to be covered by the GNU General Public
30 // License. However the source code for this file must still be made available
31 // in accordance with section (3) of the GNU General Public License.
32 //
33 // This exception does not invalidate any other reasons why a work based on
34 // this file might be covered by the GNU General Public License.
35 //
36 // Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
37 // at http://sources.redhat.com/ecos/ecos-license
38 // -------------------------------------------
39 //####ECOSGPLCOPYRIGHTEND####
40 //===========================================================================
41 //#####DESCRIPTIONBEGIN####
42 //
43 // Author(s): jlarmour
44 // Contributors: jlarmour
45 // Date: 1998-02-13
46 // Purpose:
47 // Description:
48 // Usage:
49 //
50 //####DESCRIPTIONEND####
51 //
52 //===========================================================================
53
54 // CONFIGURATION
55
56 #include <pkgconf/libm.h> // Configuration header
57
58 // Include the Math library?
59 #ifdef CYGPKG_LIBM
60
61 // Derived from code with the following copyright
62
63
64 /* @(#)s_logb.c 1.3 95/01/18 */
65 /*
66 * ====================================================
67 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
68 *
69 * Developed at SunSoft, a Sun Microsystems, Inc. business.
70 * Permission to use, copy, modify, and distribute this
71 * software is freely granted, provided that this notice
72 * is preserved.
73 * ====================================================
74 */
75
76 /*
77 * double logb(x)
78 * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
79 * Use ilogb instead.
80 */
81
82 #include "mathincl/fdlibm.h"
83
84 double logb(double x)
85 {
86 int lx,ix;
87 ix = (CYG_LIBM_HI(x))&0x7fffffff; /* high |x| */
88 lx = CYG_LIBM_LO(x); /* low x */
89 if((ix|lx)==0) return -1.0/fabs(x);
90 if(ix>=0x7ff00000) return x*x;
91 if((ix>>=20)==0) /* IEEE 754 logb */
92 return -1022.0;
93 else
94 return (double) (ix-1023);
95 }
96
97 #endif // ifdef CYGPKG_LIBM
98
99 // EOF s_logb.c