text: /*
   * 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: mbfuncinput.c,v 1.10 2007/09/12 10:15:56 wolti Exp $
   */
  
  /* ----------------------- System includes ----------------------------------*/
  #include "stdlib.h"
  #include "string.h"
  
  /* ----------------------- Platform includes --------------------------------*/
  #include "port.h"
  
  /* ----------------------- Modbus includes ----------------------------------*/
  #include "mb.h"
  #include "mbframe.h"
  #include "mbproto.h"
  #include "mbconfig.h"
  
  /* ----------------------- Defines ------------------------------------------*/
  #define MB_PDU_FUNC_READ_ADDR_OFF           ( MB_PDU_DATA_OFF )
  #define MB_PDU_FUNC_READ_REGCNT_OFF         ( MB_PDU_DATA_OFF + 2 )
  #define MB_PDU_FUNC_READ_SIZE               ( 4 )
  #define MB_PDU_FUNC_READ_REGCNT_MAX         ( 0x007D )
  
  #define MB_PDU_FUNC_READ_RSP_BYTECNT_OFF    ( MB_PDU_DATA_OFF )
  
  /* ----------------------- Static functions ---------------------------------*/
  eMBException    prveMBError2Exception(eMBErrorCode eErrorCode);
  
  /* ----------------------- Start implementation -----------------------------*/
  #if MB_FUNC_READ_INPUT_ENABLED > 0
  
  eMBException
  eMBFuncReadInputRegister(UCHAR* pucFrame, USHORT* usLen)
  {
  	USHORT          usRegAddress;
  	USHORT          usRegCount;
  	UCHAR*          pucFrameCur;
  
  	eMBException    eStatus = MB_EX_NONE;
  	eMBErrorCode    eRegStatus;
  
  	if(*usLen == (MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN)) {
  		usRegAddress = (USHORT)(pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8);
  		usRegAddress |= (USHORT)(pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1]);
  		usRegAddress++;
  
  		usRegCount = (USHORT)(pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF] << 8);
  		usRegCount |= (USHORT)(pucFrame[MB_PDU_FUNC_READ_REGCNT_OFF + 1]);
  
  		/* Check if the number of registers to read is valid. If not
  		 * return Modbus illegal data value exception.
  		 */
  		if((usRegCount >= 1)
  		        && (usRegCount < MB_PDU_FUNC_READ_REGCNT_MAX)) {
  			/* Set the current PDU data pointer to the beginning. */
  			pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
  			*usLen = MB_PDU_FUNC_OFF;
  
  			/* First byte contains the function code. */
  			*pucFrameCur++ = MB_FUNC_READ_INPUT_REGISTER;
  			*usLen += 1;
  
  			/* Second byte in the response contain the number of bytes. */
  			*pucFrameCur++ = (UCHAR)(usRegCount * 2);
  			*usLen += 1;
  
  			eRegStatus =
  			    eMBRegInputCB(pucFrameCur, usRegAddress, usRegCount);
  
  			/* If an error occured convert it into a Modbus exception. */
  			if(eRegStatus != MB_ENOERR) {
  				eStatus = prveMBError2Exception(eRegStatus);
  			} else {
  				*usLen += usRegCount * 2;
  			}
  		} else {
  			eStatus = MB_EX_ILLEGAL_DATA_VALUE;
  		}
  	} else {
  		/* Can't be a valid read input register request because the length
  		 * is incorrect. */
  		eStatus = MB_EX_ILLEGAL_DATA_VALUE;
  	}
  
  	return eStatus;
  }
  
  #endif
  