//! - \b CAN_STS_TXREQUEST - if a message object's TxRequest bit is set, that
//! means that a transmission is pending on that object.  The application can
//! use this to determine which objects are still waiting to send a message.
//! - \b CAN_STS_NEWDAT - if a message object's NewDat bit is set, that means
//! that a new message has been received in that object, and has not yet been
//! picked up by the host application
//! - \b CAN_STS_MSGVAL - if a message object's MsgVal bit is set, that means
//! it has a valid configuration programmed.  The host application can use this
//! to determine which message objects are empty/unused.
//!
//! \return Returns the value of the status register.
//
//*****************************************************************************
unsigned long
CANStatusGet(unsigned long ulBase, tCANStsReg eStatusReg)
{
    unsigned long ulStatus;

    //
    // Check the arguments.
    //
    ASSERT((ulBase == CAN0_BASE) ||
           (ulBase == CAN1_BASE) ||
           (ulBase == CAN2_BASE));

    switch(eStatusReg)
    {
        //
        // Just return the global CAN status register since that is what was
        // requested.
        //
        case CAN_STS_CONTROL:
        {
            ulStatus = CANRegRead(ulBase + CAN_O_STS);
            CANRegWrite(ulBase + CAN_O_STS,
                        ~(CAN_STS_RXOK | CAN_STS_TXOK | CAN_STS_LEC_M));
            break;
        }

        //
        // Combine the Transmit status bits into one 32bit value.
        //
        case CAN_STS_TXREQUEST:
        {
            ulStatus = CANRegRead(ulBase + CAN_O_TXRQ1);
            ulStatus |= CANRegRead(ulBase + CAN_O_TXRQ2) << 16;
            break;
        }

        //
        // Combine the New Data status bits into one 32bit value.
        //
        case CAN_STS_NEWDAT:
        {
            ulStatus = CANRegRead(ulBase + CAN_O_NWDA1);
            ulStatus |= CANRegRead(ulBase + CAN_O_NWDA2) << 16;
            break;
        }

        //
        // Combine the Message valid status bits into one 32bit value.
        //
        case CAN_STS_MSGVAL:
        {
            ulStatus = CANRegRead(ulBase + CAN_O_MSG1VAL);
            ulStatus |= CANRegRead(ulBase + CAN_O_MSG2VAL) << 16;
            break;
        }

        //
        // Unknown CAN status requested so return 0.
        //
        default:
        {
            ulStatus = 0;
            break;
        }
    }
    return(ulStatus);
}

//*****************************************************************************
//
//! Reads the CAN controller error counter register.
//!
//! \param ulBase is the base address of the CAN controller.
//! \param pulRxCount is a pointer to storage for the receive error counter.
//! \param pulTxCount is a pointer to storage for the transmit error counter.
//!
//! Reads the error counter register and returns the transmit and receive error
//! counts to the caller along with a flag indicating if the controller receive
//! counter has reached the error passive limit.  The values of the receive and
//! transmit error counters are returned through the pointers provided as
//! parameters.
//!
//! After this call, \e *pulRxCount will hold the current receive error count
//! and \e *pulTxCount will hold the current transmit error count.
//!
//! \return Returns \b true if the receive error count has reached the error
//! passive limit, and \b false if the error count is below the error passive
//! limit.
//
//*****************************************************************************
tBoolean
CANErrCntrGet(unsigned long ulBase, unsigned long *pulRxCount,
              unsigned long *pulTxCount)
{
    unsigned long ulCANError;

    //
    // Check the arguments.
    //
    ASSERT((ulBase == CAN0_BASE) ||
           (ulBase == CAN1_BASE) ||
           (ulBase == CAN2_BASE));

    //
    // Read the current count of transmit/receive errors.
    //
    ulCANError = CANRegRead(ulBase + CAN_O_ERR);

    //
    // Extract the error numbers from the register value.
    //
    *pulRxCount = (ulCANError & CAN_ERR_REC_M) >> CAN_ERR_REC_S;
    *pulTxCount = (ulCANError & CAN_ERR_TEC_M) >> CAN_ERR_TEC_S;

    if(ulCANError & CAN_ERR_RP)
    {
        return(true);
    }
    return(false);
}

//*****************************************************************************
//
//! Configures a message object in the CAN controller.
//!
//! \param ulBase is the base address of the CAN controller.
//! \param ulObjID is the object number to configure (1-32).
//! \param pMsgObject is a pointer to a structure containing message object
//! settings.
//! \param eMsgType indicates the type of message for this object.
//!
//! This function is used to configure any one of the 32 message objects in the
//! CAN controller.  A message object can be configured as any type of CAN
//! message object as well as several options for automatic transmission and
//! reception.  This call also allows the message object to be configured to
//! generate interrupts on completion of message receipt or transmission.  The
//! message object can also be configured with a filter/mask so that actions
//! are only taken when a message that meets certain parameters is seen on the
//! CAN bus.
//!
//! The \e eMsgType parameter must be one of the following values:
//!
//! - \b MSG_OBJ_TYPE_TX - CAN transmit message object.
//! - \b MSG_OBJ_TYPE_TX_REMOTE - CAN transmit remote request message object.
//! - \b MSG_OBJ_TYPE_RX - CAN receive message object.
//! - \b MSG_OBJ_TYPE_RX_REMOTE - CAN receive remote request message object.
//! - \b MSG_OBJ_TYPE_RXTX_REMOTE - CAN remote frame receive remote, then
//! transmit message object.
//!
//! The message object pointed to by \e pMsgObject must be populated by the
//! caller, as follows:
//!
//! - \e ulMsgID - contains the message ID, either 11 or 29 bits.
//! - \e ulMsgIDMask - mask of bits from \e ulMsgID that must match if
//! identifier filtering is enabled.
//! - \e ulFlags
//!   - Set \b MSG_OBJ_TX_INT_ENABLE flag to enable interrupt on transmission.
//!   - Set \b MSG_OBJ_RX_INT_ENABLE flag to enable interrupt on receipt.
//!   - Set \b MSG_OBJ_USE_ID_FILTER flag to enable filtering based on the
//!   identifier mask specified by \e ulMsgIDMask.
//! - \e ulMsgLen - the number of bytes in the message data.  This should be
//! non-zero even for a remote frame; it should match the expected bytes of the
//! data responding data frame.
//! - \e pucMsgData - points to a buffer containing up to 8 bytes of data for a
//! data frame.
//!
//! To send a data frame or remote frame directly, take the following steps:
//!
//! -# Set \e tMsgObjType to \b MSG_OBJ_TYPE_TX.
//! -# Set \e ulMsgID to the message ID.
//! -# Set \e ulFlags Set \b MSG_OBJ_TX_INT_ENABLE to to get an interrupt when
//! the message is sent.  To disable filtering based on message identifiers, do
//! not set \b MSG_OBJ_USE_ID_FILTER.
//! -# Set \e ulMsgLen to the number of bytes in the data frame.
//! -# Set \e pucMsgData to point to an array containing the bytes in the
//! message (if a data frame, this is not applicable; if a remote frame, it is
//! a good idea to set this to point to a valid buffer).
//! -# Call this function with \e ulObjID set to one of the 32 object buffers.
//!
//! To receive a specific data frame, take the following steps:
//!
//! -# Set \e tMsgObjType to \b MSG_OBJ_TYPE_RX.
//! -# Set \e ulMsgID to the full message ID, or a partial mask to use partial
//! ID matching.
//! -# Set \e ulMsgIDMask bits that should be used for masking during
//! comparison.
//! -# Set \e ulFlags as follows:
//!   - Set \b MSG_OBJ_TX_INT_ENABLE flag to be interrupted when the data frame
//!   is received.
//!   - Set \b MSG_OBJ_USE_ID_FILTER flag to enable identifier based filtering.
//! -# Set \e ulMsgLen to the number of bytes in the expected data frame.
//! -# The buffer pointed to by \e pucMsgData is not used for this call.
//! -# Call this function with \e ulObjID set to one of the 32 object buffers.
//!
//! If you specify a message object buffer that already contains a message
//! definition, it will be overwritten.
//!
//! \return None.
//
//*****************************************************************************
void
CANMessageSet(unsigned long ulBase, unsigned long ulObjID,
              tCANMsgObject *pMsgObject, tMsgObjType eMsgType)
{
    unsigned short usCmdMaskReg;
    unsigned short usMaskReg[2];
    unsigned short usArbReg[2];
    unsigned short usMsgCtrl;
    tBoolean bTransferData;
    tBoolean bUseExtendedID;

    bTransferData = 0;

    //
    // Check the arguments.
    //
    ASSERT((ulBase == CAN0_BASE) ||
           (ulBase == CAN1_BASE) ||
           (ulBase == CAN2_BASE));
    ASSERT((ulObjID <= 32) && (ulObjID != 0));
    ASSERT((eMsgType == MSG_OBJ_TYPE_TX) ||
           (eMsgType == MSG_OBJ_TYPE_TX_REMOTE) ||
           (eMsgType == MSG_OBJ_TYPE_RX) ||
           (eMsgType == MSG_OBJ_TYPE_RX_REMOTE) ||
           (eMsgType == MSG_OBJ_TYPE_TX_REMOTE) ||
           (eMsgType == MSG_OBJ_TYPE_RXTX_REMOTE));

    //
    // Wait for busy bit to clear
    //
    while(CANRegRead(ulBase + CAN_O_IF1CRQ) & CAN_IF1CRQ_BUSY)
    {
    }

    //
    // See if we need to use an extended identifier or not.
    //
    if((pMsgObject->ulMsgID > CAN_MAX_11BIT_MSG_ID) ||
       (pMsgObject->ulFlags & MSG_OBJ_EXTENDED_ID))
    {
        bUseExtendedID = 1;
    }
    else
    {
        bUseExtendedID = 0;
    }

    //
    // This is always a write to the Message object as this call is setting a
    // message object.  This call will also always set all size bits so it sets
    // both data bits.  The call will use the CONTROL register to set control
    // bits so this bit needs to be set as well.
    //
    usCmdMaskReg = (CAN_IF1CMSK_WRNRD | CAN_IF1CMSK_DATAA | CAN_IF1CMSK_DATAB |
                    CAN_IF1CMSK_CONTROL);

    //
    // Initialize the values to a known state before filling them in based on
    // the type of message object that is being configured.
    //
    usArbReg[0] = 0;
    usMsgCtrl = 0;
    usMaskReg[0] = 0;
    usMaskReg[1] = 0;

    switch(eMsgType)
    {
        //
        // Transmit message object.
        //
        case MSG_OBJ_TYPE_TX:
        {
            //
            // Set the TXRQST bit and the reset the rest of the register.
            //
            usMsgCtrl |= CAN_IF1MCTL_TXRQST;
            usArbReg[1] = CAN_IF1ARB2_DIR;
            bTransferData = 1;
            break;
        }

        //
        // Transmit remote request message object
        //
        case MSG_OBJ_TYPE_TX_REMOTE:
        {
            //
            // Set the TXRQST bit and the reset the rest of the register.
            //
            usMsgCtrl |= CAN_IF1MCTL_TXRQST;
            usArbReg[1] = 0;
            break;
        }

        //
        // Receive message object.
        //
        case MSG_OBJ_TYPE_RX:
        {
            //
            // This clears the DIR bit along with everthing else.  The TXRQST
            // bit was cleard by defaulting usMsgCtrl to 0.
            //
            usArbReg[1] = 0;
            break;
        }

        //
        // Receive remote request message object.
        //
        case MSG_OBJ_TYPE_RX_REMOTE:
        {
            //
            // The DIR bit is set to one for remote receivers.  The TXRQST bit
            // was cleard by defaulting usMsgCtrl to 0.
            //
            usArbReg[1] = CAN_IF1ARB2_DIR;

            //
            // Set this object so that it only indicates that a remote frame
            // was received and allow for software to handle it by sending back
            // a data frame.
            //
            usMsgCtrl = CAN_IF1MCTL_UMASK;

            //
            // Use the full Identifier by default.
            //
            usMaskReg[0] = 0xffff;
            usMaskReg[1] = 0x1fff;

            //
            // Make sure to send the mask to the message object.
            //
            usCmdMaskReg |= CAN_IF1CMSK_MASK;
            break;
        }

        //
        // Remote frame receive remote, with auto-transmit message object.
        //
        case MSG_OBJ_TYPE_RXTX_REMOTE:
        {
            //
            // Oddly the DIR bit is set to one for remote receivers.
            //
            usArbReg[1] = CAN_IF1ARB2_DIR;

            //
            // Set this object to auto answer if a matching identifier is seen.
            //
            usMsgCtrl = CAN_IF1MCTL_RMTEN | CAN_IF1MCTL_UMASK;

            //
            // The data to be returned needs to be filled in.
            //
            bTransferData = 1;
            break;
        }

        //
        // This case should never happen due to the ASSERT statement at the
        // beginning of this function.
        //
        default:
        {
            return;
        }
    }

    //
    // Configure the Mask Registers.
    //
    if(pMsgObject->ulFlags & MSG_OBJ_USE_ID_FILTER)
    {
        if(bUseExtendedID)
        {
            //
            // Set the 29 bits of Identifier mask that were requested.
            //
            usMaskReg[0] = pMsgObject->ulMsgIDMask & CAN_IF1MSK1_IDMSK_M;
            usMaskReg[1] = ((pMsgObject->ulMsgIDMask >> 16) &
                            CAN_IF1MSK2_IDMSK_M);
        }