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comparison packages/language/c/libc/current/src/stdlib/ldiv.cxx @ 0:3111d98ba7b3 ecos-v1_1-release

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Initial commit of eCos version 1.1
author jlarmour
date Tue, 11 May 1999 11:16:07 +0000
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children 443894e2e912
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-1:000000000000 0:3111d98ba7b3
1 //===========================================================================
2 //
3 // ldiv.cxx
4 //
5 // Real alternative for inline implementation of the ANSI standard
6 // ldiv() utility function defined in section 7.10.6.4 of the standard
7 //
8 //===========================================================================
9 //####COPYRIGHTBEGIN####
10 //
11 // -------------------------------------------
12 // The contents of this file are subject to the Cygnus eCos Public License
13 // Version 1.0 (the "License"); you may not use this file except in
14 // compliance with the License. You may obtain a copy of the License at
15 // http://sourceware.cygnus.com/ecos
16 //
17 // Software distributed under the License is distributed on an "AS IS"
18 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
19 // License for the specific language governing rights and limitations under
20 // the License.
21 //
22 // The Original Code is eCos - Embedded Cygnus Operating System, released
23 // September 30, 1998.
24 //
25 // The Initial Developer of the Original Code is Cygnus. Portions created
26 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved.
27 // -------------------------------------------
28 //
29 //####COPYRIGHTEND####
30 //===========================================================================
31 //#####DESCRIPTIONBEGIN####
32 //
33 // Author(s): jlarmour
34 // Contributors: jlarmour@cygnus.co.uk
35 // Date: 1998-02-13
36 // Purpose:
37 // Description:
38 // Usage:
39 //
40 //####DESCRIPTIONEND####
41 //
42 //===========================================================================
43 //
44 // This code is based on code with the following copyright:
45 //
46 /*
47 * Copyright (c) 1990 Regents of the University of California.
48 * All rights reserved.
49 *
50 * This code is derived from software contributed to Berkeley by
51 * Chris Torek.
52 *
53 * Redistribution and use in source and binary forms, with or without
54 * modification, are permitted provided that the following conditions
55 * are met:
56 * 1. Redistributions of source code must retain the above copyright
57 * notice, this list of conditions and the following disclaimer.
58 * 2. Redistributions in binary form must reproduce the above copyright
59 * notice, this list of conditions and the following disclaimer in the
60 * documentation and/or other materials provided with the distribution.
61 * 3. All advertising materials mentioning features or use of this software
62 * must display the following acknowledgement:
63 * This product includes software developed by the University of
64 * California, Berkeley and its contributors.
65 * 4. Neither the name of the University nor the names of its contributors
66 * may be used to endorse or promote products derived from this software
67 * without specific prior written permission.
68 *
69 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
70 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
71 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
72 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
73 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
74 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
75 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
76 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
77 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
78 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
79 * SUCH DAMAGE.
80 */
81
82
83 // CONFIGURATION
84
85 #include <pkgconf/libc.h> // Configuration header
86
87 // Include the C library?
88 #ifdef CYGPKG_LIBC
89
90 // INCLUDES
91
92 #include <cyg/infra/cyg_type.h> // Common type definitions and support
93 #include <cyg/infra/cyg_trac.h> // Tracing support
94
95 // We don't want the inline versions of stdlib functions defined here
96
97 #ifdef CYGIMP_LIBC_STDLIB_INLINES
98 #undef CYGIMP_LIBC_STDLIB_INLINES
99 #endif
100
101 #include <stddef.h> // NULL, wchar_t and size_t from compiler
102 #include <stdlib.h> // Main header for stdlib functions
103 #include "clibincl/stdlibsupp.hxx" // Support for stdlib functions
104
105
106 // EXPORTED SYMBOLS
107
108 externC ldiv_t
109 ldiv( long numer, long denom ) CYGPRI_LIBC_WEAK_ALIAS("_ldiv");
110
111
112 // FUNCTIONS
113
114 ldiv_t
115 _ldiv( long numer, long denom )
116 {
117 ldiv_t result;
118
119 CYG_REPORT_FUNCNAMETYPE( "_ldiv", "quotient: %d");
120 CYG_REPORT_FUNCARG2( "numer=%d, denom=%d", numer, denom );
121
122 // The ANSI standard says that |r.quot| <= |n/d|, where
123 // n/d is to be computed in infinite precision. In other
124 // words, we should always truncate the quotient towards
125 // 0, never -infinity.
126 //
127 // Machine ldivision and remainer may work either way when
128 // one or both of n or d is negative. If only one is
129 // negative and r.quot has been truncated towards -inf,
130 // r.rem will have the same sign as denom and the opposite
131 // sign of num; if both are negative and r.quot has been
132 // truncated towards -inf, r.rem will be positive (will
133 // have the opposite sign of num). These are considered
134 // `wrong'.
135 //
136 // If both are num and denom are positive, r will always
137 // be positive.
138 //
139 // This all boils down to:
140 // if num >= 0, but r.rem < 0, we got the wrong answer.
141 // In that case, to get the right answer, add 1 to r.quot and
142 // subtract denom from r.rem.
143
144 result.quot = numer / denom;
145 result.rem = numer % denom;
146
147 if ( (numer >= 0) && (result.rem < 0) )
148 {
149 result.quot++;
150 result.rem -= denom;
151 } // if
152
153 CYG_REPORT_RETVAL( result.quot );
154
155 return result;
156 } // _ldiv()
157
158 #endif // ifdef CYGPKG_LIBC
159
160 // EOF ldiv.cxx