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//===========================================================================

//

//      memcmp.cxx

//

//      ANSI standard memcmp() routine

//

//===========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

// Software Foundation; either version 2 or (at your option) any later version.

//

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// WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

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// this file might be covered by the GNU General Public License.

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// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

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//####ECOSGPLCOPYRIGHTEND####

//===========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):     jlarmour

// Contributors:  

// Date:          2000-04-14

// Purpose:     

// Description: 

// Usage:       

//

//####DESCRIPTIONEND####

//

//===========================================================================

// CONFIGURATION

#include <pkgconf/libc_string.h>   // Configuration header

// 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 <cyg/libc/string/stringsupp.hxx> // Useful string function support and

                                          // prototypes

// EXPORTED SYMBOLS

externC int

memcmp( const void *s1, const void *s2, size_t n ) \

    CYGBLD_ATTRIB_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 );

    if (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()

// EOF memcmp.cxx