/*
 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (c) 2006-2018 Christian Walter <cwalter@embedded-solutions.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 1.27 2007/02/18 23:45:41 wolti Exp $
 */

/* ----------------------- System includes ----------------------------------*/
#include "stdlib.h"
#include "string.h"

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

/* ----------------------- Modbus includes ----------------------------------*/

#include "mb.h"
#include "mbconfig.h"
#include "mbframe.h"
#include "mbproto.h"
#include "mbfunc.h"

#include "mbport.h"

#if MB_SLAVE_RTU_ENABLED == 1

#include "mbrtu.h"

#endif
#if MB_SLAVE_ASCII_ENABLED == 1
#include "mbascii.h"
#endif
#if MB_SLAVE_TCP_ENABLED == 1
#include "mbtcp.h"
#endif

#ifndef MB_PORT_HAS_CLOSE
#define MB_PORT_HAS_CLOSE 0
#endif

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

static UCHAR 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.
 * Using for Modbus Slave
 */
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.
 * Using for Modbus Slave
 */
BOOL ( *pxMBFrameCBByteReceived )(eMBRTUSlaveObj *pObj);

BOOL ( *pxMBFrameCBTransmitterEmpty )(eMBRTUSlaveObj *pObj);

BOOL ( *pxMBPortCBTimerExpired )(eMBRTUSlaveObj *pObj);

BOOL ( *pxMBFrameCBReceiveFSMCur )(void);

BOOL ( *pxMBFrameCBTransmitFSMCur )(void);

/* An array of Modbus functions handlers which associates Modbus function
 * codes with implementing functions.
 */
static xMBFunctionHandler xFuncHandlers[MB_FUNC_HANDLERS_MAX] = {
#if MB_FUNC_OTHER_REP_SLAVEID_ENABLED > 0
        {MB_FUNC_OTHER_REPORT_SLAVEID, eMBFuncReportSlaveID},
#endif
#if MB_FUNC_READ_INPUT_ENABLED > 0
        {MB_FUNC_READ_INPUT_REGISTER, eMBFuncReadInputRegister},
#endif
#if MB_FUNC_READ_HOLDING_ENABLED > 0
        {MB_FUNC_READ_HOLDING_REGISTER, eMBFuncReadHoldingRegister},
#endif
#if MB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED > 0
        {MB_FUNC_WRITE_MULTIPLE_REGISTERS, eMBFuncWriteMultipleHoldingRegister},
#endif
#if MB_FUNC_WRITE_HOLDING_ENABLED > 0
        {MB_FUNC_WRITE_REGISTER, eMBFuncWriteHoldingRegister},
#endif
#if MB_FUNC_READWRITE_HOLDING_ENABLED > 0
        {MB_FUNC_READWRITE_MULTIPLE_REGISTERS, eMBFuncReadWriteMultipleHoldingRegister},
#endif
#if MB_FUNC_WRITE_FILE_ENABLE > 0
        {MB_FUNC_WRITE_FILE, eMBFuncWriteFile}
#endif
#if MB_FUNC_WRITE_DEVICE_SERIAL_ENABLE > 0
        {MB_FUNC_WRITE_DEVICE_SERIAL_NUMBER, eMBFuncWriteDeviceSerial}
#endif
#if MB_FUNC_READ_COILS_ENABLED > 0
        {MB_FUNC_READ_COILS, eMBFuncReadCoils},
#endif
#if MB_FUNC_WRITE_COIL_ENABLED > 0
        {MB_FUNC_WRITE_SINGLE_COIL, eMBFuncWriteCoil},
#endif
#if MB_FUNC_WRITE_MULTIPLE_COILS_ENABLED > 0
        {MB_FUNC_WRITE_MULTIPLE_COILS, eMBFuncWriteMultipleCoils},
#endif
#if MB_FUNC_READ_DISCRETE_INPUTS_ENABLED > 0
        {MB_FUNC_READ_DISCRETE_INPUTS, eMBFuncReadDiscreteInputs},
#endif
};


/* ----------------------- Start implementation -----------------------------*/
eMBErrorCode
eMBInit(eMBRTUSlaveObj *obj) {
    eMBErrorCode eStatus = MB_ENOERR;

    /* check preconditions */
    if ((obj->ucSlaveAddress == MB_ADDRESS_BROADCAST) ||
        (obj->ucSlaveAddress < MB_ADDRESS_MIN) || (obj->ucSlaveAddress > MB_ADDRESS_MAX)) {
        eStatus = MB_EINVAL;
    } else {
        ucMBAddress = obj->ucSlaveAddress;

        switch (obj->eMode) {
#if MB_SLAVE_RTU_ENABLED > 0
            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(obj);
                break;
#endif
#if MB_SLAVE_ASCII_ENABLED > 0
                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;
                break;
        }

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

#if MB_SLAVE_TCP_ENABLED > 0
eMBErrorCode
eMBTCPInit( USHORT 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(UCHAR ucFunctionCode, pxMBFunctionHandler pxHandler) {
    int i;
    eMBErrorCode eStatus;

    if ((0 < ucFunctionCode) && (ucFunctionCode <= 127)) {
        ENTER_CRITICAL_SECTION();
        if (pxHandler != NULL) {
            for (i = 0; i < 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 != MB_FUNC_HANDLERS_MAX) ? MB_ENOERR : MB_ENORES;
        } else {
            for (i = 0; i < 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(eMBRTUSlaveObj *pObj) {
    eMBErrorCode eStatus = MB_ENOERR;

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


eMBErrorCode
eMBEnable(eMBRTUSlaveObj *obj) {
    eMBErrorCode eStatus = MB_ENOERR;

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

eMBErrorCode
eMBDisable(eMBRTUSlaveObj *pObj) {
    eMBErrorCode eStatus;

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

eMBErrorCode eMBPoll(eMBRTUSlaveObj *obj) {
    static UCHAR ucRcvAddress;
    static UCHAR ucFunctionCode;
    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(obj, &eEvent) == TRUE) {
        switch (eEvent) {
            case EV_READY:
                break;

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

            case EV_EXECUTE:
                ucFunctionCode = obj->ucMBFrame[MB_PDU_FUNC_OFF];
                eException = MB_EX_ILLEGAL_FUNCTION;
                for (i = 0; i < 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(obj, obj->ucMBFrame, &obj->usLength);
                        break;
                    }
                }

                /* If the request was not sent to the broadcast address we
                 * return a reply. */
                if (eException != MB_EX_NONE) {
                    /* An exception occured. Build an error frame. */
                    obj->usLength = 0;
                    obj->ucMBFrame[obj->usLength++] = (UCHAR) (ucFunctionCode | MB_FUNC_ERROR);
                    obj->ucMBFrame[obj->usLength++] = eException;
                }
                eStatus = peMBFrameSendCur(obj, obj->ucMBFrame, obj->usLength);
                break;

            case EV_FRAME_SENT:
                break;
        }
    }
    return MB_ENOERR;
}