halcrc.c

开发源代码的CPU卡的COS源程序。

/* ============================================================================
   Project Name : jayaCard
   Module Name  : proto/hal/avr/halcrc.c
   Version : $Id: halcrc.c,v 1.4 2004/01/11 09:56:32 dgil Exp $

	Description: CRC calculus

    The Original Code is jayaCard code.

    The Initial Developer of the Original Code is Gilles Dumortier.

    Portions created by the Initial Developer are Copyright (C) 2002-2004 the
    Initial Developer. All Rights Reserved.

    Contributor(s):

    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 of the License, 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 program; see http://www.gnu.org/licenses/gpl.html

   History Rev	Description
   072603 dgil	wrote it from generic implementation
   ============================================================================
*/

#include "precomp.h"

/* =========================================================================
	__hal_tcl_init_crc()

	initialise the CRC to begin a calculation.

	use tcl_type { TCL_TYPEA; TCL_TYPEB } to initialise the correct CRC.

   ========================================================================= */

void __hal_tcl_init_crc(void)
{
	if (tcl_type==TCL_TYPEA) {
		__avr_crc = 0x6363;
	} else {
		__avr_crc = 0xFFFF;
	}
}

/* =========================================================================
	__hal_crc_init()

	initialise the CRC to begin a calculation.
   ========================================================================= */

void __hal_crc_init(void)
{
	__avr_crc = 0x6363;
}

/* =========================================================================
	__avr_calculate_crc()
   ========================================================================= */

void __avr_calculate_crc(jbyte by)
{
	by = (by^(jbyte)(__avr_crc & 0x00FF));
	by = (by^(by<<4));
	__avr_crc = (__avr_crc >> 8)^((jword)by << 8)^((jword)by<<3)^((jword)by>>4);
}

/* =========================================================================
	__avr_locrc()
   ========================================================================= */

jbyte __avr_locrc(void)
{
	if (tcl_type==TCL_TYPEA) {
		return LOBYTE(__avr_crc);
	} else {
		return LOBYTE(~__avr_crc);
	}
}

/* =========================================================================
	__avr_hicrc()
   ========================================================================= */

jbyte __avr_hicrc(void)
{
	if (tcl_type==TCL_TYPEA) {
		return HIBYTE(__avr_crc);
	} else {
		return HIBYTE(~__avr_crc);
	}
}

/* =========================================================================
	That's all folks !
   ========================================================================= */