source: SVN/cambria/redboot/packages/language/c/libc/string/current/src/memcmp.cxx @ 1

Last change on this file since 1 was 1, checked in by Tim Harvey, 2 years ago

restored latest version of files from server backup

Signed-off-by: Tim Harvey <tharvey@…>

File size: 5.9 KB
Line 
1//===========================================================================
2//
3//      memcmp.cxx
4//
5//      ANSI standard memcmp() routine
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: 
45// Date:          2000-04-14
46// Purpose:     
47// Description:
48// Usage:       
49//
50//####DESCRIPTIONEND####
51//
52//===========================================================================
53
54// CONFIGURATION
55
56#include <pkgconf/libc_string.h>   // Configuration header
57
58// INCLUDES
59
60#include <cyg/infra/cyg_type.h>    // Common type definitions
61#include <cyg/infra/cyg_trac.h>    // Tracing support
62#include <cyg/infra/cyg_ass.h>     // Assertion support
63#include <string.h>                // Header for this file
64#include <stddef.h>           // Compiler definitions such as size_t, NULL etc.
65#include <cyg/libc/string/stringsupp.hxx> // Useful string function support and
66                                          // prototypes
67
68
69// EXPORTED SYMBOLS
70
71externC int
72memcmp( const void *s1, const void *s2, size_t n ) \
73    CYGBLD_ATTRIB_WEAK_ALIAS(__memcmp);
74
75// FUNCTIONS
76
77int
78__memcmp( const void *s1, const void *s2, size_t n )
79{
80    int retval;
81
82    CYG_REPORT_FUNCNAMETYPE( "__memcmp", "returning %d" );
83    CYG_REPORT_FUNCARG3( "s1=%08x, s2=%08x, n=%d", s1, s2, n );
84
85    if (n)
86    {
87        CYG_CHECK_DATA_PTR( s1, "s1 is not a valid pointer!" );
88        CYG_CHECK_DATA_PTR( s2, "s2 is not a valid pointer!" );
89    }
90
91#if defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || defined(__OPTIMIZE_SIZE__)
92    const unsigned char *m1 = (const unsigned char *) s1;
93    const unsigned char *m2 = (const unsigned char *) s2;
94   
95    while (n--)
96    {
97        if (*m1 != *m2)
98        {
99            retval = *m1 - *m2;
100            CYG_REPORT_RETVAL( retval );
101            return retval;
102        }
103        m1++;
104        m2++;
105    }
106    CYG_REPORT_RETVAL( 0 );
107    return 0;
108#else 
109    const unsigned char *m1 = (const unsigned char *) s1;
110    const unsigned char *m2 = (const unsigned char *) s2;
111    const CYG_WORD *aligned_m1;
112    const CYG_WORD *aligned_m2;
113   
114    // If the size is too small, or either pointer is unaligned,
115    // then we punt to the byte compare loop.  Hopefully this will
116    // not turn up in inner loops.
117    if (CYG_LIBC_STR_OPT_TOO_SMALL(n) || CYG_LIBC_STR_UNALIGNED2(m1,m2))
118    {
119        while (n--)
120        {
121            if (*m1 != *m2)
122            {
123                retval = *m1 - *m2;
124                CYG_REPORT_RETVAL( retval );
125                return retval;
126            }
127            m1++;
128            m2++;
129        }
130        CYG_REPORT_RETVAL( 0 );
131        return 0;
132    }
133   
134    // Otherwise, load and compare the blocks of memory one
135    // word at a time.
136    aligned_m1 = (const CYG_WORD *) m1;
137    aligned_m2 = (const CYG_WORD *) m2;
138    while (n > CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE)
139    {
140        if (*aligned_m1 != *aligned_m2) 
141        {
142            // This block of characters has a mismatch, somewhere.
143            // xoring them together and then testing for null would
144            // be fastest, but this is clearer code.
145            m1 = (const unsigned char *)aligned_m1;
146            m2 = (const unsigned char *)aligned_m2;
147            while (n--)
148            {
149                if (*m1 != *m2)
150                {
151                    retval = *m1 - *m2;
152                    CYG_REPORT_RETVAL( retval );
153                    return retval;
154                }
155                m1++;
156                m2++;
157            }
158            // NOT REACHED
159        }
160        aligned_m1++;
161        aligned_m2++;
162        n -= CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE;
163    }
164   
165    // checking the last few characters
166   
167    m1 = (const unsigned char *)aligned_m1;
168    m2 = (const unsigned char *)aligned_m2;
169   
170    while (n--)
171    {
172        if (*m1 != *m2)
173        {
174            retval = *m1 - *m2;
175            CYG_REPORT_RETVAL( retval );
176            return retval;
177        }
178        m1++;
179        m2++;
180    }
181   
182    CYG_REPORT_RETVAL( 0 );
183    return 0;
184#endif // not defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) ||
185       //     defined(__OPTIMIZE_SIZE__)
186} // __memcmp()
187
188// EOF memcmp.cxx
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