diff packages/language/c/libc/current/src/string/memcmp.cxx @ 0:3111d98ba7b3 ecos-v1_1-release

Initial commit of eCos version 1.1
author jlarmour
date Tue, 11 May 1999 11:16:07 +0000
parents
children 443894e2e912
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+//===========================================================================
+//
+//      memcmp.cxx
+//
+//      ANSI standard memcmp() routine
+//
+//===========================================================================
+//####COPYRIGHTBEGIN####
+//
+// -------------------------------------------
+// The contents of this file are subject to the Cygnus eCos Public License
+// Version 1.0 (the "License"); you may not use this file except in
+// compliance with the License.  You may obtain a copy of the License at
+// http://sourceware.cygnus.com/ecos
+// 
+// Software distributed under the License is distributed on an "AS IS"
+// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the
+// License for the specific language governing rights and limitations under
+// the License.
+// 
+// The Original Code is eCos - Embedded Cygnus Operating System, released
+// September 30, 1998.
+// 
+// The Initial Developer of the Original Code is Cygnus.  Portions created
+// by Cygnus are Copyright (C) 1998 Cygnus Solutions.  All Rights Reserved.
+// -------------------------------------------
+//
+//####COPYRIGHTEND####
+//===========================================================================
+//#####DESCRIPTIONBEGIN####
+//
+// Author(s):   jlarmour
+// Contributors:  jlarmour@cygnus.co.uk
+// Date:        1998-02-13
+// Purpose:     
+// Description: 
+// Usage:       
+//
+//####DESCRIPTIONEND####
+//
+//===========================================================================
+
+// CONFIGURATION
+
+#include <pkgconf/libc.h>   // Configuration header
+
+// Include the C library?
+#ifdef CYGPKG_LIBC     
+
+// INCLUDES
+
+#include <cyg/infra/cyg_type.h>    // Common type definitions
+#include <cyg/infra/cyg_trac.h>    // Tracing support
+#include <cyg/infra/cyg_ass.h>     // Assertion support
+#include <string.h>                // Header for this file
+#include <stddef.h>           // Compiler definitions such as size_t, NULL etc.
+#include "clibincl/stringsupp.hxx" // Useful string function support and
+                                   // prototypes
+
+
+// EXPORTED SYMBOLS
+
+externC int
+memcmp( const void *s1, const void *s2, size_t n ) \
+    CYGPRI_LIBC_WEAK_ALIAS("_memcmp");
+
+// FUNCTIONS
+
+int
+_memcmp( const void *s1, const void *s2, size_t n )
+{
+    int retval;
+
+    CYG_REPORT_FUNCNAMETYPE( "_memcmp", "returning %d" );
+    CYG_REPORT_FUNCARG3( "s1=%08x, s2=%08x, n=%d", s1, s2, n );
+
+    CYG_CHECK_DATA_PTR( s1, "s1 is not a valid pointer!" );
+    CYG_CHECK_DATA_PTR( s2, "s2 is not a valid pointer!" );
+
+#if defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || defined(__OPTIMIZE_SIZE__)
+    const unsigned char *m1 = (const unsigned char *) s1;
+    const unsigned char *m2 = (const unsigned char *) s2;
+    
+    while (n--)
+    {
+        if (*m1 != *m2)
+        {
+            retval = *m1 - *m2;
+            CYG_REPORT_RETVAL( retval );
+            return retval;
+        }
+        m1++;
+        m2++;
+    }
+    CYG_REPORT_RETVAL( 0 );
+    return 0;
+#else  
+    const unsigned char *m1 = (const unsigned char *) s1;
+    const unsigned char *m2 = (const unsigned char *) s2;
+    const CYG_WORD *aligned_m1;
+    const CYG_WORD *aligned_m2;
+    
+    // If the size is too small, or either pointer is unaligned,
+    // then we punt to the byte compare loop.  Hopefully this will
+    // not turn up in inner loops.
+    if (CYG_LIBC_STR_OPT_TOO_SMALL(n) || CYG_LIBC_STR_UNALIGNED2(m1,m2))
+    {
+        while (n--)
+        {
+            if (*m1 != *m2)
+            {
+                retval = *m1 - *m2;
+                CYG_REPORT_RETVAL( retval );
+                return retval;
+            }
+            m1++;
+            m2++;
+        }
+        CYG_REPORT_RETVAL( 0 );
+        return 0;
+    }
+    
+    // Otherwise, load and compare the blocks of memory one 
+    // word at a time.
+    aligned_m1 = (const CYG_WORD *) m1;
+    aligned_m2 = (const CYG_WORD *) m2;
+    while (n > CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE)
+    {
+        if (*aligned_m1 != *aligned_m2) 
+        {
+            // This block of characters has a mismatch, somewhere.
+            // xoring them together and then testing for null would
+            // be fastest, but this is clearer code.
+            m1 = (const unsigned char *)aligned_m1;
+            m2 = (const unsigned char *)aligned_m2;
+            while (n--)
+            {
+                if (*m1 != *m2)
+                {
+                    retval = *m1 - *m2;
+                    CYG_REPORT_RETVAL( retval );
+                    return retval;
+                }
+                m1++;
+                m2++;
+            }
+            // NOT REACHED
+        }
+        aligned_m1++;
+        aligned_m2++;
+        n -= CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE;
+    }
+    
+    // checking the last few characters
+    
+    m1 = (const unsigned char *)aligned_m1;
+    m2 = (const unsigned char *)aligned_m2;
+    
+    while (n--)
+    {
+        if (*m1 != *m2)
+        {
+            retval = *m1 - *m2;
+            CYG_REPORT_RETVAL( retval );
+            return retval;
+        }
+        m1++;
+        m2++;
+    }
+    
+    CYG_REPORT_RETVAL( 0 );
+    return 0;
+#endif // not defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) ||
+       //     defined(__OPTIMIZE_SIZE__)
+} // _memcmp()
+
+#endif // CYGPKG_LIBC     
+
+// EOF memcmp.cxx