/*
 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (c) 2006 Christian Walter <wolti@sil.at>
 * 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 * File: $Id: mb.c,v 1.28 2010/06/06 13:54:40 wolti Exp $
 */

/* ----------------------- System includes ----------------------------------*/
#include <nuttx/config.h>
#include <stdlib.h>
#include <string.h>

/* ----------------------- Platform includes --------------------------------*/
#include "port.h"

/* ----------------------- Modbus includes ----------------------------------*/
#include <apps/modbus/mb.h>
#include <apps/modbus/mbframe.h>
#include <apps/modbus/mbproto.h>
#include <apps/modbus/mbfunc.h>

#include <apps/modbus/mbport.h>

#ifdef CONFIG_MB_RTU_ENABLED
#include "mbrtu.h"
#endif

#ifdef CONFIG_MB_ASCII_ENABLED
#include "mbascii.h"
#endif

#ifdef CONFIG_MB_TCP_ENABLED
#include "mbtcp.h"
#endif

#ifndef MB_PORT_HAS_CLOSE
#define MB_PORT_HAS_CLOSE 0
#endif

/* ----------------------- Static variables ---------------------------------*/

static uint8_t  ucMBAddress;
static eMBMode  eMBCurrentMode;

static enum
{
    STATE_ENABLED,
    STATE_DISABLED,
    STATE_NOT_INITIALIZED
} eMBState = STATE_NOT_INITIALIZED;

/* Functions pointer which are initialized in eMBInit(). Depending on the
 * mode (RTU or ASCII) the are set to the correct implementations.
 */
static peMBFrameSend peMBFrameSendCur;
static pvMBFrameStart pvMBFrameStartCur;
static pvMBFrameStop pvMBFrameStopCur;
static peMBFrameReceive peMBFrameReceiveCur;
static pvMBFrameClose pvMBFrameCloseCur;

/* Callback functions required by the porting layer. They are called when
 * an external event has happend which includes a timeout or the reception
 * or transmission of a character.
 */
bool(*pxMBFrameCBByteReceived)(void);
bool(*pxMBFrameCBTransmitterEmpty)(void);
bool(*pxMBPortCBTimerExpired)(void);

bool(*pxMBFrameCBReceiveFSMCur)(void);
bool(*pxMBFrameCBTransmitFSMCur)(void);

/* An array of Modbus functions handlers which associates Modbus function
 * codes with implementing functions.
 */
static xMBFunctionHandler xFuncHandlers[CONFIG_MB_FUNC_HANDLERS_MAX] = {
#ifdef CONFIG_MB_FUNC_OTHER_REP_SLAVEID_ENABLED
    {MB_FUNC_OTHER_REPORT_SLAVEID, eMBFuncReportSlaveID},
#endif
#ifdef CONFIG_MB_FUNC_READ_INPUT_ENABLED
    {MB_FUNC_READ_INPUT_REGISTER, eMBFuncReadInputRegister},
#endif
#ifdef CONFIG_MB_FUNC_READ_HOLDING_ENABLED
    {MB_FUNC_READ_HOLDING_REGISTER, eMBFuncReadHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED
    {MB_FUNC_WRITE_MULTIPLE_REGISTERS, eMBFuncWriteMultipleHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_HOLDING_ENABLED
    {MB_FUNC_WRITE_REGISTER, eMBFuncWriteHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_READWRITE_HOLDING_ENABLED
    {MB_FUNC_READWRITE_MULTIPLE_REGISTERS, eMBFuncReadWriteMultipleHoldingRegister},
#endif
#ifdef CONFIG_MB_FUNC_READ_COILS_ENABLED
    {MB_FUNC_READ_COILS, eMBFuncReadCoils},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_COIL_ENABLED
    {MB_FUNC_WRITE_SINGLE_COIL, eMBFuncWriteCoil},
#endif
#ifdef CONFIG_MB_FUNC_WRITE_MULTIPLE_COILS_ENABLED
    {MB_FUNC_WRITE_MULTIPLE_COILS, eMBFuncWriteMultipleCoils},
#endif
#ifdef CONFIG_MB_FUNC_READ_DISCRETE_INPUTS_ENABLED
    {MB_FUNC_READ_DISCRETE_INPUTS, eMBFuncReadDiscreteInputs},
#endif
};

/* ----------------------- Start implementation -----------------------------*/
eMBErrorCode
eMBInit(eMBMode eMode, uint8_t ucSlaveAddress, uint8_t ucPort, speed_t ulBaudRate, eMBParity eParity)
{
    eMBErrorCode    eStatus = MB_ENOERR;

    /* check preconditions */

    if ((ucSlaveAddress == MB_ADDRESS_BROADCAST) ||
        (ucSlaveAddress < MB_ADDRESS_MIN) || (ucSlaveAddress > MB_ADDRESS_MAX))
    {
        eStatus = MB_EINVAL;
    }
    else
    {
        ucMBAddress = ucSlaveAddress;

        switch (eMode)
        {
#ifdef CONFIG_MB_RTU_ENABLED
        case MB_RTU:
            pvMBFrameStartCur = eMBRTUStart;
            pvMBFrameStopCur = eMBRTUStop;
            peMBFrameSendCur = eMBRTUSend;
            peMBFrameReceiveCur = eMBRTUReceive;
            pvMBFrameCloseCur = MB_PORT_HAS_CLOSE ? vMBPortClose : NULL;
            pxMBFrameCBByteReceived = xMBRTUReceiveFSM;
            pxMBFrameCBTransmitterEmpty = xMBRTUTransmitFSM;
            pxMBPortCBTimerExpired = xMBRTUTimerT35Expired;

            eStatus = eMBRTUInit(ucMBAddress, ucPort, ulBaudRate, eParity);
            break;
#endif
#ifdef CONFIG_MB_ASCII_ENABLED
        case MB_ASCII:
            pvMBFrameStartCur = eMBASCIIStart;
            pvMBFrameStopCur = eMBASCIIStop;
            peMBFrameSendCur = eMBASCIISend;
            peMBFrameReceiveCur = eMBASCIIReceive;
            pvMBFrameCloseCur = MB_PORT_HAS_CLOSE ? vMBPortClose : NULL;
            pxMBFrameCBByteReceived = xMBASCIIReceiveFSM;
            pxMBFrameCBTransmitterEmpty = xMBASCIITransmitFSM;
            pxMBPortCBTimerExpired = xMBASCIITimerT1SExpired;

            eStatus = eMBASCIIInit(ucMBAddress, ucPort, ulBaudRate, eParity);
            break;
#endif
        default:
            eStatus = MB_EINVAL;
        }

        if (eStatus == MB_ENOERR)
        {
            if (!xMBPortEventInit())
            {
                /* port dependent event module initalization failed. */
                eStatus = MB_EPORTERR;
            }
            else
            {
                eMBCurrentMode = eMode;
                eMBState = STATE_DISABLED;
            }
        }
    }
    return eStatus;
}

#ifdef CONFIG_MB_TCP_ENABLED
eMBErrorCode
eMBTCPInit(uint16_t ucTCPPort)
{
    eMBErrorCode    eStatus = MB_ENOERR;

    if ((eStatus = eMBTCPDoInit(ucTCPPort)) != MB_ENOERR)
    {
        eMBState = STATE_DISABLED;
    }
    else if (!xMBPortEventInit())
    {
        /* Port dependent event module initalization failed. */
        eStatus = MB_EPORTERR;
    }
    else
    {
        pvMBFrameStartCur = eMBTCPStart;
        pvMBFrameStopCur = eMBTCPStop;
        peMBFrameReceiveCur = eMBTCPReceive;
        peMBFrameSendCur = eMBTCPSend;
        pvMBFrameCloseCur = MB_PORT_HAS_CLOSE ? vMBTCPPortClose : NULL;
        ucMBAddress = MB_TCP_PSEUDO_ADDRESS;
        eMBCurrentMode = MB_TCP;
        eMBState = STATE_DISABLED;
    }
    return eStatus;
}
#endif

eMBErrorCode
eMBRegisterCB(uint8_t ucFunctionCode, pxMBFunctionHandler pxHandler)
{
    int             i;
    eMBErrorCode    eStatus;

    if ((0 < ucFunctionCode) && (ucFunctionCode <= 127))
    {
        ENTER_CRITICAL_SECTION();
        if (pxHandler != NULL)
        {
            for(i = 0; i < CONFIG_MB_FUNC_HANDLERS_MAX; i++)
            {
                if ((xFuncHandlers[i].pxHandler == NULL) ||
                    (xFuncHandlers[i].pxHandler == pxHandler))
                {
                    xFuncHandlers[i].ucFunctionCode = ucFunctionCode;
                    xFuncHandlers[i].pxHandler = pxHandler;
                    break;
                }
            }
            eStatus = (i != CONFIG_MB_FUNC_HANDLERS_MAX) ? MB_ENOERR : MB_ENORES;
        }
        else
        {
            for(i = 0; i < CONFIG_MB_FUNC_HANDLERS_MAX; i++)
            {
                if (xFuncHandlers[i].ucFunctionCode == ucFunctionCode)
                {
                    xFuncHandlers[i].ucFunctionCode = 0;
                    xFuncHandlers[i].pxHandler = NULL;
                    break;
                }
            }
            /* Remove can't fail. */
            eStatus = MB_ENOERR;
        }
        EXIT_CRITICAL_SECTION();
    }
    else
    {
        eStatus = MB_EINVAL;
    }
    return eStatus;
}


eMBErrorCode
eMBClose(void)
{
    eMBErrorCode    eStatus = MB_ENOERR;

    if (eMBState == STATE_DISABLED)
    {
        if (pvMBFrameCloseCur != NULL)
        {
            pvMBFrameCloseCur();
        }
    }
    else
    {
        eStatus = MB_EILLSTATE;
    }
    return eStatus;
}

eMBErrorCode
eMBEnable(void)
{
    eMBErrorCode    eStatus = MB_ENOERR;

    if (eMBState == STATE_DISABLED)
    {
        /* Activate the protocol stack. */
        pvMBFrameStartCur();
        eMBState = STATE_ENABLED;
    }
    else
    {
        eStatus = MB_EILLSTATE;
    }
    return eStatus;
}

eMBErrorCode
eMBDisable(void)
{
    eMBErrorCode    eStatus;

    if (eMBState == STATE_ENABLED)
    {
        pvMBFrameStopCur();
        eMBState = STATE_DISABLED;
        eStatus = MB_ENOERR;
    }
    else if (eMBState == STATE_DISABLED)
    {
        eStatus = MB_ENOERR;
    }
    else
    {
        eStatus = MB_EILLSTATE;
    }
    return eStatus;
}

eMBErrorCode
eMBPoll(void)
{
    static uint8_t     *ucMBFrame;
    static uint8_t      ucRcvAddress;
    static uint8_t      ucFunctionCode;
    static uint16_t     usLength;
    static eMBException eException;

    int             i;
    eMBErrorCode    eStatus = MB_ENOERR;
    eMBEventType    eEvent;

    /* Check if the protocol stack is ready. */
    if (eMBState != STATE_ENABLED)
    {
        return MB_EILLSTATE;
    }

    /* Check if there is a event available. If not return control to caller.
     * Otherwise we will handle the event. */
    if (xMBPortEventGet(&eEvent) == true)
    {
        switch (eEvent)
        {
        case EV_READY:
            break;

        case EV_FRAME_RECEIVED:
            eStatus = peMBFrameReceiveCur(&ucRcvAddress, &ucMBFrame, &usLength);
            if (eStatus == MB_ENOERR)
            {
                /* Check if the frame is for us. If not ignore the frame. */
                if ((ucRcvAddress == ucMBAddress) || (ucRcvAddress == MB_ADDRESS_BROADCAST))
                {
                    (void)xMBPortEventPost(EV_EXECUTE);
                }
            }
            break;

        case EV_EXECUTE:
            ucFunctionCode = ucMBFrame[MB_PDU_FUNC_OFF];
            eException = MB_EX_ILLEGAL_FUNCTION;
            for(i = 0; i < CONFIG_MB_FUNC_HANDLERS_MAX; i++)
            {
                /* No more function handlers registered. Abort. */
                if (xFuncHandlers[i].ucFunctionCode == 0)
                {
                    break;
                }
                else if (xFuncHandlers[i].ucFunctionCode == ucFunctionCode)
                {
                    eException = xFuncHandlers[i].pxHandler(ucMBFrame, &usLength);
                    break;
                }
            }

            /* If the request was not sent to the broadcast address we
             * return a reply. */
            if (ucRcvAddress != MB_ADDRESS_BROADCAST)
            {
                if (eException != MB_EX_NONE)
                {
                    /* An exception occured. Build an error frame. */
                    usLength = 0;
                    ucMBFrame[usLength++] = (uint8_t)(ucFunctionCode | MB_FUNC_ERROR);
                    ucMBFrame[usLength++] = eException;
                }
#ifdef CONFIG_MB_ASCII_ENABLED
                if ((eMBCurrentMode == MB_ASCII) && CONFIG_MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS)
                {
                    vMBPortTimersDelay(CONFIG_MB_ASCII_TIMEOUT_WAIT_BEFORE_SEND_MS);
                }
#endif
                (void)peMBFrameSendCur(ucMBAddress, ucMBFrame, usLength);
            }
            break;

        case EV_FRAME_SENT:
            break;
        }
    }
    return MB_ENOERR;
}