// ----------------------------------------------------------------------------
/*
 * Copyright (c) 2007 Fabian Greif, Roboterclub Aachen e.V.
 *  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id: mcp2515_get_message.c 758 2010-08-01 23:50:48Z jacobsen $
 */
// ----------------------------------------------------------------------------

#include "mcp2515_private.h"
#ifdef	SUPPORT_FOR_MCP2515__

static uint8_t lastRxBuf1Status;


// ----------------------------------------------------------------------------

uint8_t mcp2515_get_message(tCAN *msg)
{
	uint8_t addr;
	
	#ifdef	RXnBF_FUNKTION
		if (!IS_SET(MCP2515_RX0BF))
			addr = SPI_READ_RX;
		else if (!IS_SET(MCP2515_RX1BF))
			addr = SPI_READ_RX | 0x04;
		else
			return 0;
	#else
		// read status
		uint8_t status = mcp2515_read_status(SPI_RX_STATUS);
		
		if (lastRxBuf1Status & status){
			// message in buffer 1 from last time so read it first this time
			addr = SPI_READ_RX | 0x04;
			lastRxBuf1Status = 0;
		}
		else if (_bit_is_set(status,6)) {
			// message in buffer 0
			addr = SPI_READ_RX;
			lastRxBuf1Status = status & (uint8_t)0x80;
		}
		else if (_bit_is_set(status,7)) {
			// message in buffer 1
			addr = SPI_READ_RX | 0x04;
			lastRxBuf1Status = 0;
		}
		else {
			// Error: no message available
			return 0;
		}
	#endif
	
	RESET(MCP2515_CS);
	spi_putc(addr);
	
	// CAN ID auslesen und ueberpruefen
	uint8_t tmp = mcp2515_read_id(&msg->id);
	#if SUPPORT_EXTENDED_CANID
		msg->flags.extended = tmp & 0x01;
	#else
		if (tmp & 0x01) {
			// Nachrichten mit extended ID verwerfen
			SET(MCP2515_CS);
			#ifdef	RXnBF_FUNKTION
			if (!IS_SET(MCP2515_RX0BF))
			#else
			if (_bit_is_set(status, 6))
			#endif
				mcp2515_bit_modify(CANINTF, (1<<RX0IF), 0);
			else
				mcp2515_bit_modify(CANINTF, (1<<RX1IF), 0);
			
			return 0;
		}
	#endif
	
	// read DLC
	uint8_t length = spi_putc(0xff);
	#ifdef RXnBF_FUNKTION
		if (!(tmp & 0x01))
			msg->flags.rtr = (tmp & 0x02) ? 1 : 0;
		else
			msg->flags.rtr = (length & (1<<RTR)) ? 1 : 0;
	#else
		msg->flags.rtr = (_bit_is_set(status, 3)) ? 1 : 0;
	#endif
	
	length &= 0x0f;
	msg->length = length;
	// read data
	uint8_t i;
	for (i=0;i<length;i++) {
		msg->data[i] = spi_putc(0xff);
	}
	SET(MCP2515_CS);
	
	// clear interrupt flag
	#ifdef RXnBF_FUNKTION
	if (!IS_SET(MCP2515_RX0BF))
	#else
	if (_bit_is_set(status, 6))
	#endif
		mcp2515_bit_modify(CANINTF, (1<<RX0IF), 0);
	else
		mcp2515_bit_modify(CANINTF, (1<<RX1IF), 0);
	
	#ifdef RXnBF_FUNKTION
		return 1;
	#else
		return (status & 0x07) + 1;
	#endif
}

#endif	// SUPPORT_FOR_MCP2515__