adtools/clib2

/*
 * $Id: string_strncmp.c,v 1.5 2010-08-20 15:33:36 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _STDLIB_NULL_POINTER_CHECK_H
#include "stdlib_null_pointer_check.h"
#endif /* _STDLIB_NULL_POINTER_CHECK_H */

/****************************************************************************/

#ifndef _STRING_HEADERS_H
#include "string_headers.h"
#endif /* _STRING_HEADERS_H */

/****************************************************************************/

int
strncmp(const char *s1, const char *s2, size_t n)
{
    int result = 0;

    assert( s1 != NULL && s2 != NULL );
    assert( (int)n >= 0 );

    #if defined(CHECK_FOR_NULL_POINTERS)
    {
        if(s1 == NULL || s2 == NULL)
        {
            __set_errno(EFAULT);
            goto out;
        }
    }
    #endif /* CHECK_FOR_NULL_POINTERS */

    /* If the number of characters is 0 or negative, then this
     * function is supposed to have no effect.
     */
    if(s1 != s2 && (int)n > 0)
    {
        while(n-- > 0)
        {
            if((*s1) == (*s2))
            {
                if((*s1) == '\0')
                    break;

                s1++;
                s2++;
            }
            else
            {
                int c1,c2;
                
                /* The comparison must be performed as if the
                   characters were unsigned characters. */
                c1 = *(unsigned char *)s1;
                c2 = *(unsigned char *)s2;
                
                result = c1 - c2;
                break;
            }
        }
    }

 out:

    return(result);
}