strncat.cxx

ecos实时嵌入式操作系统

//===========================================================================
//
//      strncat.cxx
//
//      ANSI standard strncat() 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.
//
// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
// 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.
//
// This exception does not invalidate any other reasons why a work based on
// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####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 char *
strncat( char *s1, const char *s2, size_t n ) \
    CYGBLD_ATTRIB_WEAK_ALIAS(__strncat);

// FUNCTIONS

char *
__strncat( char *s1, const char *s2, size_t n)
{
    CYG_REPORT_FUNCNAMETYPE( "__strncat", "returning %08x" );
    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__)
    char *s = s1;
    
    while (*s1)
        s1++;
    while (n-- != 0 && (*s1++ = *s2++))
    {
        if (n == 0)
            *s1 = '\0';
    }
    
    CYG_REPORT_RETVAL( s );

    return s;
#else
    char *s = s1;
    
    // Skip over the data in s1 as quickly as possible.
    if (!CYG_LIBC_STR_UNALIGNED (s1))
    {
        CYG_WORD *aligned_s1 = (CYG_WORD *)s1;
        while (!CYG_LIBC_STR_DETECTNULL (*aligned_s1))
            aligned_s1++;
        
        s1 = (char *)aligned_s1;
    }
    
    while (*s1)
        s1++;
    
    // s1 now points to the its trailing null character, now copy
    // up to N bytes from S2 into S1 stopping if a NULL is encountered
    // in S2.
    // 
    // It is not safe to use strncpy here since it copies EXACTLY N
    // characters, NULL padding if necessary.

    while (n-- != 0 && (*s1++ = *s2++))
    {
        if (n == 0)
            *s1 = '\0';
    }
    
    CYG_REPORT_RETVAL( s );

    return s;
#endif // not defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) ||
       //     defined(__OPTIMIZE_SIZE__)
} // __strncat()

// EOF strncat.cxx