486 lines
15 KiB
C
486 lines
15 KiB
C
/*
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* FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
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* Copyright (c) 2006 Christian Walter <wolti@sil.at>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* File: $Id: mbascii.c,v 1.15 2007/02/18 23:46:48 wolti Exp $
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*/
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/* ----------------------- System includes ----------------------------------*/
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#include "stdlib.h"
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#include "string.h"
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/* ----------------------- Platform includes --------------------------------*/
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#include "port.h"
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/* ----------------------- Modbus includes ----------------------------------*/
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#include "mb.h"
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#include "mbconfig.h"
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#include "mbascii.h"
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#include "mbframe.h"
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#include "mbcrc.h"
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#include "mbport.h"
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#if MB_ASCII_ENABLED > 0
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/* ----------------------- Defines ------------------------------------------*/
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#define MB_ASCII_DEFAULT_CR '\r' /*!< Default CR character for Modbus ASCII. */
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#define MB_ASCII_DEFAULT_LF '\n' /*!< Default LF character for Modbus ASCII. */
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#define MB_SER_PDU_SIZE_MIN 3 /*!< Minimum size of a Modbus ASCII frame. */
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#define MB_SER_PDU_SIZE_MAX 256 /*!< Maximum size of a Modbus ASCII frame. */
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#define MB_SER_PDU_SIZE_LRC 1 /*!< Size of LRC field in PDU. */
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#define MB_SER_PDU_ADDR_OFF 0 /*!< Offset of slave address in Ser-PDU. */
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#define MB_SER_PDU_PDU_OFF 1 /*!< Offset of Modbus-PDU in Ser-PDU. */
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/* ----------------------- Type definitions ---------------------------------*/
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typedef enum
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{
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STATE_RX_IDLE, /*!< Receiver is in idle state. */
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STATE_RX_RCV, /*!< Frame is beeing received. */
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STATE_RX_WAIT_EOF /*!< Wait for End of Frame. */
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} eMBRcvState;
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typedef enum
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{
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STATE_TX_IDLE, /*!< Transmitter is in idle state. */
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STATE_TX_START, /*!< Starting transmission (':' sent). */
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STATE_TX_DATA, /*!< Sending of data (Address, Data, LRC). */
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STATE_TX_END, /*!< End of transmission. */
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STATE_TX_NOTIFY /*!< Notify sender that the frame has been sent. */
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} eMBSndState;
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typedef enum
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{
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BYTE_HIGH_NIBBLE, /*!< Character for high nibble of byte. */
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BYTE_LOW_NIBBLE /*!< Character for low nibble of byte. */
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} eMBBytePos;
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/* ----------------------- Static functions ---------------------------------*/
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static UCHAR prvucMBCHAR2BIN( UCHAR ucCharacter );
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static UCHAR prvucMBBIN2CHAR( UCHAR ucByte );
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static UCHAR prvucMBLRC( UCHAR * pucFrame, USHORT usLen );
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/* ----------------------- Static variables ---------------------------------*/
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static volatile eMBSndState eSndState;
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static volatile eMBRcvState eRcvState;
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/* We reuse the Modbus RTU buffer because only one buffer is needed and the
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* RTU buffer is bigger. */
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extern volatile UCHAR ucRTUBuf[];
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static volatile UCHAR *ucASCIIBuf = ucRTUBuf;
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static volatile USHORT usRcvBufferPos;
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static volatile eMBBytePos eBytePos;
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static volatile UCHAR *pucSndBufferCur;
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static volatile USHORT usSndBufferCount;
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static volatile UCHAR ucLRC;
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static volatile UCHAR ucMBLFCharacter;
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/* ----------------------- Start implementation -----------------------------*/
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eMBErrorCode
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eMBASCIIInit( UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity )
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{
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eMBErrorCode eStatus = MB_ENOERR;
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( void )ucSlaveAddress;
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ENTER_CRITICAL_SECTION( );
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ucMBLFCharacter = MB_ASCII_DEFAULT_LF;
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if( xMBPortSerialInit( ucPort, ulBaudRate, 7, eParity ) != TRUE )
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{
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eStatus = MB_EPORTERR;
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}
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else if( xMBPortTimersInit( MB_ASCII_TIMEOUT_SEC * 20000UL ) != TRUE )
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{
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eStatus = MB_EPORTERR;
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}
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EXIT_CRITICAL_SECTION( );
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return eStatus;
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}
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void
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eMBASCIIStart( void )
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{
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ENTER_CRITICAL_SECTION( );
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vMBPortSerialEnable( TRUE, FALSE );
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eRcvState = STATE_RX_IDLE;
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EXIT_CRITICAL_SECTION( );
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/* No special startup required for ASCII. */
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( void )xMBPortEventPost( EV_READY );
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}
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void
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eMBASCIIStop( void )
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{
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ENTER_CRITICAL_SECTION( );
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vMBPortSerialEnable( FALSE, FALSE );
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vMBPortTimersDisable( );
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EXIT_CRITICAL_SECTION( );
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}
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eMBErrorCode
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eMBASCIIReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength )
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{
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eMBErrorCode eStatus = MB_ENOERR;
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ENTER_CRITICAL_SECTION( );
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assert( usRcvBufferPos < MB_SER_PDU_SIZE_MAX );
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/* Length and CRC check */
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if( ( usRcvBufferPos >= MB_SER_PDU_SIZE_MIN )
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&& ( prvucMBLRC( ( UCHAR * ) ucASCIIBuf, usRcvBufferPos ) == 0 ) )
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{
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/* Save the address field. All frames are passed to the upper layed
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* and the decision if a frame is used is done there.
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*/
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*pucRcvAddress = ucASCIIBuf[MB_SER_PDU_ADDR_OFF];
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/* Total length of Modbus-PDU is Modbus-Serial-Line-PDU minus
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* size of address field and CRC checksum.
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*/
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*pusLength = ( USHORT )( usRcvBufferPos - MB_SER_PDU_PDU_OFF - MB_SER_PDU_SIZE_LRC );
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/* Return the start of the Modbus PDU to the caller. */
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*pucFrame = ( UCHAR * ) & ucASCIIBuf[MB_SER_PDU_PDU_OFF];
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}
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else
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{
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eStatus = MB_EIO;
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}
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EXIT_CRITICAL_SECTION( );
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return eStatus;
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}
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eMBErrorCode
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eMBASCIISend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
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{
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eMBErrorCode eStatus = MB_ENOERR;
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UCHAR usLRC;
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ENTER_CRITICAL_SECTION( );
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/* Check if the receiver is still in idle state. If not we where to
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* slow with processing the received frame and the master sent another
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* frame on the network. We have to abort sending the frame.
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*/
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if( eRcvState == STATE_RX_IDLE )
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{
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/* First byte before the Modbus-PDU is the slave address. */
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pucSndBufferCur = ( UCHAR * ) pucFrame - 1;
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usSndBufferCount = 1;
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/* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
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pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress;
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usSndBufferCount += usLength;
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/* Calculate LRC checksum for Modbus-Serial-Line-PDU. */
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usLRC = prvucMBLRC( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
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ucASCIIBuf[usSndBufferCount++] = usLRC;
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/* Activate the transmitter. */
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eSndState = STATE_TX_START;
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vMBPortSerialEnable( FALSE, TRUE );
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}
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else
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{
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eStatus = MB_EIO;
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}
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EXIT_CRITICAL_SECTION( );
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return eStatus;
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}
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BOOL
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xMBASCIIReceiveFSM( void )
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{
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BOOL xNeedPoll = FALSE;
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UCHAR ucByte;
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UCHAR ucResult;
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assert( eSndState == STATE_TX_IDLE );
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( void )xMBPortSerialGetByte( ( CHAR * ) & ucByte );
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switch ( eRcvState )
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{
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/* A new character is received. If the character is a ':' the input
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* buffer is cleared. A CR-character signals the end of the data
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* block. Other characters are part of the data block and their
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* ASCII value is converted back to a binary representation.
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*/
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case STATE_RX_RCV:
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/* Enable timer for character timeout. */
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vMBPortTimersEnable( );
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if( ucByte == ':' )
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{
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/* Empty receive buffer. */
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eBytePos = BYTE_HIGH_NIBBLE;
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usRcvBufferPos = 0;
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}
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else if( ucByte == MB_ASCII_DEFAULT_CR )
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{
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eRcvState = STATE_RX_WAIT_EOF;
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}
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else
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{
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ucResult = prvucMBCHAR2BIN( ucByte );
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switch ( eBytePos )
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{
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/* High nibble of the byte comes first. We check for
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* a buffer overflow here. */
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case BYTE_HIGH_NIBBLE:
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if( usRcvBufferPos < MB_SER_PDU_SIZE_MAX )
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{
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ucASCIIBuf[usRcvBufferPos] = ( UCHAR )( ucResult << 4 );
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eBytePos = BYTE_LOW_NIBBLE;
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break;
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}
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else
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{
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/* not handled in Modbus specification but seems
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* a resonable implementation. */
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eRcvState = STATE_RX_IDLE;
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/* Disable previously activated timer because of error state. */
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vMBPortTimersDisable( );
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}
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break;
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case BYTE_LOW_NIBBLE:
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ucASCIIBuf[usRcvBufferPos++] |= ucResult;
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eBytePos = BYTE_HIGH_NIBBLE;
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break;
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}
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}
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break;
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case STATE_RX_WAIT_EOF:
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if( ucByte == ucMBLFCharacter )
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{
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/* Disable character timeout timer because all characters are
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* received. */
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vMBPortTimersDisable( );
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/* Receiver is again in idle state. */
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eRcvState = STATE_RX_IDLE;
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/* Notify the caller of eMBASCIIReceive that a new frame
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* was received. */
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xNeedPoll = xMBPortEventPost( EV_FRAME_RECEIVED );
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}
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else if( ucByte == ':' )
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{
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/* Empty receive buffer and back to receive state. */
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eBytePos = BYTE_HIGH_NIBBLE;
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usRcvBufferPos = 0;
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eRcvState = STATE_RX_RCV;
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/* Enable timer for character timeout. */
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vMBPortTimersEnable( );
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}
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else
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{
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/* Frame is not okay. Delete entire frame. */
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eRcvState = STATE_RX_IDLE;
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}
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break;
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case STATE_RX_IDLE:
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if( ucByte == ':' )
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{
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/* Enable timer for character timeout. */
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vMBPortTimersEnable( );
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/* Reset the input buffers to store the frame. */
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usRcvBufferPos = 0;;
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eBytePos = BYTE_HIGH_NIBBLE;
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eRcvState = STATE_RX_RCV;
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}
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break;
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}
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return xNeedPoll;
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}
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BOOL
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xMBASCIITransmitFSM( void )
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{
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BOOL xNeedPoll = FALSE;
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UCHAR ucByte;
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assert( eRcvState == STATE_RX_IDLE );
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switch ( eSndState )
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{
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/* Start of transmission. The start of a frame is defined by sending
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* the character ':'. */
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case STATE_TX_START:
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ucByte = ':';
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xMBPortSerialPutByte( ( CHAR )ucByte );
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eSndState = STATE_TX_DATA;
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eBytePos = BYTE_HIGH_NIBBLE;
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break;
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/* Send the data block. Each data byte is encoded as a character hex
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* stream with the high nibble sent first and the low nibble sent
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* last. If all data bytes are exhausted we send a '\r' character
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* to end the transmission. */
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case STATE_TX_DATA:
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if( usSndBufferCount > 0 )
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{
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switch ( eBytePos )
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{
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case BYTE_HIGH_NIBBLE:
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ucByte = prvucMBBIN2CHAR( ( UCHAR )( *pucSndBufferCur >> 4 ) );
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xMBPortSerialPutByte( ( CHAR ) ucByte );
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eBytePos = BYTE_LOW_NIBBLE;
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break;
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case BYTE_LOW_NIBBLE:
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ucByte = prvucMBBIN2CHAR( ( UCHAR )( *pucSndBufferCur & 0x0F ) );
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xMBPortSerialPutByte( ( CHAR )ucByte );
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pucSndBufferCur++;
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eBytePos = BYTE_HIGH_NIBBLE;
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usSndBufferCount--;
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break;
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}
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}
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else
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{
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xMBPortSerialPutByte( MB_ASCII_DEFAULT_CR );
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eSndState = STATE_TX_END;
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}
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break;
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/* Finish the frame by sending a LF character. */
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case STATE_TX_END:
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xMBPortSerialPutByte( ( CHAR )ucMBLFCharacter );
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/* We need another state to make sure that the CR character has
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* been sent. */
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eSndState = STATE_TX_NOTIFY;
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break;
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/* Notify the task which called eMBASCIISend that the frame has
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* been sent. */
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case STATE_TX_NOTIFY:
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eSndState = STATE_TX_IDLE;
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xNeedPoll = xMBPortEventPost( EV_FRAME_SENT );
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/* Disable transmitter. This prevents another transmit buffer
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* empty interrupt. */
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vMBPortSerialEnable( TRUE, FALSE );
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eSndState = STATE_TX_IDLE;
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break;
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/* We should not get a transmitter event if the transmitter is in
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* idle state. */
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case STATE_TX_IDLE:
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/* enable receiver/disable transmitter. */
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vMBPortSerialEnable( TRUE, FALSE );
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break;
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}
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return xNeedPoll;
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}
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BOOL
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xMBASCIITimerT1SExpired( void )
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{
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switch ( eRcvState )
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{
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/* If we have a timeout we go back to the idle state and wait for
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* the next frame.
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*/
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case STATE_RX_RCV:
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case STATE_RX_WAIT_EOF:
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eRcvState = STATE_RX_IDLE;
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break;
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default:
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assert( ( eRcvState == STATE_RX_RCV ) || ( eRcvState == STATE_RX_WAIT_EOF ) );
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break;
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}
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vMBPortTimersDisable( );
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/* no context switch required. */
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return FALSE;
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}
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static UCHAR
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prvucMBCHAR2BIN( UCHAR ucCharacter )
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{
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if( ( ucCharacter >= '0' ) && ( ucCharacter <= '9' ) )
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{
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return ( UCHAR )( ucCharacter - '0' );
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}
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else if( ( ucCharacter >= 'A' ) && ( ucCharacter <= 'F' ) )
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{
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return ( UCHAR )( ucCharacter - 'A' + 0x0A );
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}
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else
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{
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return 0xFF;
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}
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}
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static UCHAR
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prvucMBBIN2CHAR( UCHAR ucByte )
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{
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if( ucByte <= 0x09 )
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{
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return ( UCHAR )( '0' + ucByte );
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}
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else if( ( ucByte >= 0x0A ) && ( ucByte <= 0x0F ) )
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{
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return ( UCHAR )( ucByte - 0x0A + 'A' );
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}
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else
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{
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/* Programming error. */
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assert( 0 );
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}
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return '0';
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}
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static UCHAR
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prvucMBLRC( UCHAR * pucFrame, USHORT usLen )
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{
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UCHAR ucLRC = 0; /* LRC char initialized */
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while( usLen-- )
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{
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ucLRC += *pucFrame++; /* Add buffer byte without carry */
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}
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/* Return twos complement */
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ucLRC = ( UCHAR ) ( -( ( CHAR ) ucLRC ) );
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return ucLRC;
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}
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#endif
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