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113 lines
3.8 KiB
C
113 lines
3.8 KiB
C
/*
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* Harbour Project source code:
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* adler32 checksum function
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*
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* Copyright 2007 Przemyslaw Czerpak <druzus / at / priv.onet.pl>
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* www - http://harbour-project.org
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*
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* Algorithm taken from adler32.c Copyright (C) 1995-2002 Mark Adler
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING.txt. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
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*
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* As a special exception, the Harbour Project gives permission for
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* additional uses of the text contained in its release of Harbour.
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*
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* The exception is that, if you link the Harbour libraries with other
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* files to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the Harbour library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by the Harbour
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* Project under the name Harbour. If you copy code from other
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* Harbour Project or Free Software Foundation releases into a copy of
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* Harbour, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from them.
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*
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* If you write modifications of your own for Harbour, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice.
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*
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*/
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#include "hbapi.h"
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#include "hbapierr.h"
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#include "hbchksum.h"
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#define BASE 65521 /* largest prime smaller than 65536 */
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#define NMAX 5552 /* largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
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#define LOOP_DO1( buf, i ) { s1 += buf[ i ]; s2 += s1; }
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#define LOOP_DO2( buf, i ) { LOOP_DO1( buf, i ) LOOP_DO1( buf, i + 1 ) }
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#define LOOP_DO4( buf, i ) { LOOP_DO2( buf, i ) LOOP_DO2( buf, i + 2 ) }
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#define LOOP_DO8( buf, i ) { LOOP_DO4( buf, i ) LOOP_DO4( buf, i + 4 ) }
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#define LOOP_DO16( buf, i ) { LOOP_DO8( buf, i ) LOOP_DO8( buf, i + 8 ) }
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HB_U32 hb_adler32( HB_U32 adler, const void * buf, HB_SIZE len )
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{
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HB_U32 s1 = adler & 0xffff;
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HB_U32 s2 = ( adler >> 16 ) & 0xffff;
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if( buf && len )
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{
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const unsigned char * ucbuf = ( const unsigned char * ) buf;
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do
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{
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HB_ISIZ n = len < NMAX ? len : NMAX;
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len -= n;
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if( n >= 16 )
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{
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do
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{
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LOOP_DO16( ucbuf, 0 )
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ucbuf += 16;
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n -= 16;
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}
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while( n >= 16 );
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}
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if( n )
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{
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do
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{
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s1 += *ucbuf++;
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s2 += s1;
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}
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while( --n );
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}
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s1 %= BASE;
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s2 %= BASE;
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}
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while( len );
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}
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return ( s2 << 16 ) | s1;
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}
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HB_FUNC( HB_ADLER32 )
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{
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const char * szString = hb_parc( 1 );
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if( szString )
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hb_retnint( hb_adler32( ( HB_U32 ) hb_parnl( 2 ), szString, hb_parclen( 1 ) ) );
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else
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hb_errRT_BASE( EG_ARG, 3012, NULL, HB_ERR_FUNCNAME, HB_ERR_ARGS_BASEPARAMS );
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}
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