mbtowc.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 94 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
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*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
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* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
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****************************************************************************/


#include "variety.h"
#ifdef __NT__
    #include <stdlib.h>
    #include <windows.h>
    #include <winnls.h>
    #include "mbchar.h"
#endif
#include <mbstring.h>
#include "farfunc.h"



/****
***** Convert a multibyte character to a wide character.
****/

_WCRTLINK int _NEARFAR(mbtowc,_fmbtowc)( wchar_t _FFAR *pwc, const char _FFAR *ch, size_t n )
{
#ifdef __NT__
    int                 rc;
    int                 len;
    wchar_t             wch;
#endif

    /*** Catch special cases ***/
    if( ch == NULL )  return( 0 );
    if( n == 0 )  return( -1 );
    if( *ch == '\0' ) {
        if( pwc != NULL )  *pwc = L'\0';
        return( 0 );
    }
    if( _ismbblead( ch[0] )  &&  ch[1] == '\0' )  return( -1 ); /* invalid */

    /*** Convert the character ***/
    #ifdef __NT__
        len = _NEARFAR(_mbclen,_fmbclen)( ch );
        rc = MultiByteToWideChar( __MBCodePage, MB_ERR_INVALID_CHARS,
                                  (LPCSTR)ch, min(n,len), (LPWSTR)&wch, 1 );
        if( rc != 0 ) {
            if( pwc != NULL )  *pwc = wch;
            return( len );                      /* return mbchar size */
        } else {
            return( -1 );                       /* cannot convert */
        }
    #else
        if( _ismbblead(*ch) && n>=2 ) {         /* lead byte present? */
            if( pwc != NULL ) {
                *pwc = (((wchar_t)ch[0])<<8) |  /* convert to lead:trail */
                        (wchar_t)ch[1];
            }
            return( 2 );                        /* return char size */
        } else if( !_ismbblead(*ch) ) {
            if( pwc != NULL ) {
                *pwc = (wchar_t)ch[0];          /* convert to 00:byte */
            }
            return( 1 );                        /* return char size */
        } else {
            return( -1 );                       /* n==1, but char 2 bytes */
        }
    #endif
}