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

//

//      memchr.cxx

//

//      ANSI standard memchr() 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

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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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//####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 void *

memchr( const void *s, int c, size_t n )  CYGBLD_ATTRIB_WEAK_ALIAS(__memchr);

// FUNCTIONS

void *

__memchr( const void *s, int c, size_t n )

{

    CYG_REPORT_FUNCNAMETYPE( "__memchr", "returning addr %08x" );

    CYG_REPORT_FUNCARG3( "s=%08x, c=%d, n=%d", s, c, n );

    if (n)

    {

        CYG_CHECK_DATA_PTR( s, "s is not a valid pointer!" );

    }

#if defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || defined(__OPTIMIZE_SIZE__)

    const unsigned char *src = (const unsigned char *) s;

    c &= 0xff;

    while (n--)

    {

        if (*src == c)

        {

            CYG_REPORT_RETVAL( src );

            return (void *) src;

        } // if

        src++;

    }

    CYG_REPORT_RETVAL( NULL );

    return NULL;

#else

    const unsigned char *src = (const unsigned char *) s;

    CYG_WORD *aligned_src;

    CYG_WORD buffer;

    CYG_WORD mask;

    cyg_ucount8 i;

    c &= 0xff;

    // If the size is small, or src is unaligned, then 

    // use the bytewise loop.  We can hope this is rare.

    if (CYG_LIBC_STR_OPT_TOO_SMALL (n) || CYG_LIBC_STR_UNALIGNED (src))

    {

        while (n--)

        {

            if (*src == c)

            {

                CYG_REPORT_RETVAL( src );

                return (void *) src;

            } // if

            src++;

        }

        CYG_REPORT_RETVAL( NULL );

        return NULL;

    }

    // The fast code reads the ASCII one word at a time and only 

    // performs the bytewise search on word-sized segments if they

    // contain the search character, which is detected by XORing 

    // the word-sized segment with a word-sized block of the search

    // character and then detecting for the presence of NULL in the

    // result.

    aligned_src = (CYG_WORD *) src;

    mask = 0;

    for (i = 0; i < CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE; i++)

        mask = (mask << 8) + c;

    while (n > CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE)

    {

        buffer = *aligned_src;

        buffer ^=  mask;

        if (CYG_LIBC_STR_DETECTNULL (buffer))

        {

            src = (unsigned char*) aligned_src;

            for ( i = 0; i < CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE; i++ )

            {

                if (*src == c)

                {

                    CYG_REPORT_RETVAL( src );

                    return (void *) src;

                } // if

                src++;

            }

        }

        n -= CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE;

        aligned_src++;

    }

    // If there are fewer than CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE characters

    // left, then we resort to the bytewise loop.

    src = (const unsigned char *) aligned_src;

    while (n--)

    {

        if (*src == c)

        {

            CYG_REPORT_RETVAL( src );

            return (void *) src;

        } // if

        src++;

    }

    CYG_REPORT_RETVAL( NULL );

    return NULL;

#endif // not defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) ||

       //     defined(__OPTIMIZE_SIZE__)

} // __memchr()

// EOF memchr.cxx