slave.h

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/*
    liblightmodbus - a lightweight, multiplatform Modbus library
    Copyright (C) 2017 Jacek Wieczorek <mrjjot@gmail.com>

    This file is part of liblightmodbus.

    Liblightmodbus is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Liblightmodbus is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef LIGHTMODBUS_SLAVE_H
#define LIGHTMODBUS_SLAVE_H

// For C++
#ifdef __cplusplus
extern "C" {
#endif

#include <inttypes.h>
#include <stddef.h>
#include "parser.h"
#include "libconf.h"
#include "lightmodbus.h"

#ifdef LIGHTMODBUS_SLAVE_BASE

#ifdef LIGHTMODBUS_SLAVE_USER_FUNCTIONS
    struct modbusSlave;
    typedef struct modbusSlaveUserFunction
    {
        uint8_t function; 

        ModbusError ( *handler )( struct modbusSlave *status, ModbusParser *parser );
    } ModbusSlaveUserFunction;
#endif

#if defined( LIGHTMODBUS_REGISTER_CALLBACK ) || defined( LIGHTMODBUS_COIL_CALLBACK )
    #ifndef LIGHTMODBUS_EXPERIMENTAL
        #error Register callback functions are an experimental feature that may cause problems. Please define LIGHTMODBUS_EXPERIMENTAL to dismiss this error message.
    #endif

    typedef enum modbusRegisterQuery
    {
        MODBUS_REGQ_R, 
        MODBUS_REGQ_W, 
        MODBUS_REGQ_R_CHECK, 
        MODBUS_REGQ_W_CHECK 
    } ModbusRegisterQuery;

    typedef uint16_t ( *ModbusRegisterCallbackFunction )( ModbusRegisterQuery query, ModbusDataType datatype, uint16_t index, uint16_t value, void *ctx );
#endif

typedef struct modbusSlave
{
    uint8_t address; 

    //Universal register/coil callback function
    #if defined( LIGHTMODBUS_COIL_CALLBACK ) || defined( LIGHTMODBUS_REGISTER_CALLBACK )

        ModbusRegisterCallbackFunction registerCallback;

        void *registerCallbackContext;
    #endif

    //Slave registers arrays
    #ifndef LIGHTMODBUS_REGISTER_CALLBACK
        uint16_t *registers; 
        uint16_t *inputRegisters; 
        uint8_t *registerMask; 
        uint16_t registerMaskLength; 
    #endif
    uint16_t registerCount; 
    uint16_t inputRegisterCount; 

    //Slave coils array
    #ifndef LIGHTMODBUS_COIL_CALLBACK
        uint8_t *coils; 
        uint8_t *discreteInputs; 
        uint8_t *coilMask; 
        uint16_t coilMaskLength; 
    #endif
    uint16_t coilCount; 
    uint16_t discreteInputCount; 

    ModbusExceptionCode lastException;

    ModbusFrameError parseError;

    //Array of user defined functions - these can override default Modbus functions
    #ifdef LIGHTMODBUS_SLAVE_USER_FUNCTIONS

        ModbusSlaveUserFunction *userFunctions;
        uint16_t userFunctionCount; 
    #endif

    struct
    {
        #ifdef LIGHTMODBUS_STATIC_MEM_SLAVE_RESPONSE
            uint8_t frame[LIGHTMODBUS_STATIC_MEM_SLAVE_RESPONSE];
        #else
            uint8_t *frame;
        #endif

        uint8_t length;
    } response;

    struct
    {
        #ifdef LIGHTMODBUS_STATIC_MEM_SLAVE_REQUEST
            uint8_t frame[LIGHTMODBUS_STATIC_MEM_SLAVE_REQUEST];
        #else
            const uint8_t *frame;
        #endif

        uint8_t length;
    } request;

} ModbusSlave;
#endif

//Function prototypes
#ifdef LIGHTMODBUS_SLAVE_BASE

extern ModbusError modbusBuildException( ModbusSlave *status, uint8_t function, ModbusExceptionCode code );

extern ModbusError modbusParseRequest( ModbusSlave *status );

extern ModbusError modbusSlaveInit( ModbusSlave *status );

extern ModbusError modbusSlaveEnd( ModbusSlave *status );

static inline ModbusError modbusBuildExceptionErr( ModbusSlave *status, uint8_t function, ModbusExceptionCode code, ModbusFrameError parseError ) //Build an exception and write error to status->parseError
{
    if ( status == NULL ) return MODBUS_ERROR_NULLPTR;
    status->parseError = parseError;
    ModbusError err = modbusBuildException( status, function, code );
    if ( err == MODBUS_ERROR_OK ) return MODBUS_ERROR_PARSE;
    else return err;
}
#endif

// For C++ (closes `extern "C"` )
#ifdef __cplusplus
}
#endif

#endif