/*
 * hb_StrIsUTF8() function
 *
 * Copyright 2014 Przemyslaw Czerpak <druzus / at / priv.onet.pl>
 *
 * This program 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.
 *
 * This program 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 this software; see the file COPYING.txt.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA (or visit the web site https://www.gnu.org/).
 *
 * As a special exception, the Harbour Project gives permission for
 * additional uses of the text contained in its release of Harbour.
 *
 * The exception is that, if you link the Harbour libraries with other
 * files to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the Harbour library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the Harbour
 * Project under the name Harbour.  If you copy code from other
 * Harbour Project or Free Software Foundation releases into a copy of
 * Harbour, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for Harbour, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.
 *
 */

#include "hbapi.h"

HB_FUNC( HB_STRISUTF8 )
{
   HB_SIZE nLen = hb_parclen( 1 );
   HB_BOOL fUtf8 = HB_FALSE;

   if( nLen > 0 )
   {
      const char * szText = hb_parc( 1 );

      do
      {
         char c = *szText++;

         if( c & 0x80 )
         {
            int i = 0;

            while( ( c <<= 1 ) & 0x80  )
               ++i;
            if( i == 0 || ( HB_SIZE ) i >= nLen )
               break;
            nLen -= i;
            do
               if( ( *szText++ & 0xC0 ) != 0x80 )
                  break;
            while( --i );
            if( i != 0 )
               break;

            fUtf8 = HB_TRUE;
         }
      }
      while( --nLen );
      if( nLen != 0 )
         fUtf8 = HB_FALSE;
   }

   hb_retl( fUtf8 );
}