at90can_send_message.c

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// ----------------------------------------------------------------------------
/*
 * 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: at90can_send_message.c 6837 2008-11-16 19:05:15Z fabian $
 */
// ----------------------------------------------------------------------------

#include "at90can_private.h"
#ifdef  SUPPORT_FOR_AT90CAN__

#include <string.h>

// ----------------------------------------------------------------------------
void at90can_copy_message_to_mob(const can_t *msg)
{
        // write DLC (Data Length Code)
        CANCDMOB = msg->length;
        
        #if SUPPORT_EXTENDED_CANID
        
        if (msg->flags.extended) {
                // extended CAN ID
                CANCDMOB |= (1 << IDE);
                
                CANIDT4 = (uint8_t)  msg->id << 3;
                
                uint32_t temp = msg->id << 3;
                uint8_t *ptr = (uint8_t *) &temp;
                
                CANIDT3 = *(ptr + 1);
                CANIDT2 = *(ptr + 2);
                CANIDT1 = *(ptr + 3);
        }
        else {
                // standard CAN ID
                CANIDT4 = 0;
                CANIDT3 = 0;
                CANIDT2 = (uint8_t)  msg->id << 5;
                CANIDT1 = (uint16_t) msg->id >> 3;
        }
        
        #else
        
        CANIDT4 = 0;
        CANIDT3 = 0;
        CANIDT2 = (uint8_t)  msg->id << 5;
        CANIDT1 = (uint16_t) msg->id >> 3;
        
        #endif
        
        if (msg->flags.rtr) {
                CANIDT4 |= (1<<RTRTAG);
        }
        else {
                const uint8_t *p = msg->data;
                for (uint8_t i = 0;i < msg->length;i++) {
                        CANMSG = *p++;
                }
        }
}

// ----------------------------------------------------------------------------
uint8_t at90can_send_message(const can_t *msg)
{
        // check if there is any free MOb
        uint8_t mob = _find_free_mob();
        if (mob >= 15)
                return 0;
        
        // load corresponding MOb page ...
        CANPAGE = (mob << 4);
        
        // clear flags
        CANSTMOB &= 0;
        
        // ... and copy the data
        at90can_copy_message_to_mob( msg );
        
        // enable interrupt
        _enable_mob_interrupt(mob);
        
        ENTER_CRITICAL_SECTION;
        #if CAN_TX_BUFFER_SIZE == 0
                _free_buffer--;
        #elif CAN_FORCE_TX_ORDER
                _transmission_in_progress = 1;
        #endif
        LEAVE_CRITICAL_SECTION;
        
        // enable transmission
        CANCDMOB |= (1<<CONMOB0);
        
        return (mob + 1);
}

#endif  // SUPPORT_FOR_AT90CAN__