xbusparser.c

Go to the documentation of this file.

 
//  Copyright (c) 2003-2021 Xsens Technologies B.V. or subsidiaries worldwide.
//  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.  Neither the names of the copyright holders nor the names of their contributors
//      may be used to endorse or promote products derived from this software without
//      specific prior written permission.
//  
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDERS OR CONTRIBUTORS 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.THE LAWS OF THE NETHERLANDS 
//  SHALL BE EXCLUSIVELY APPLICABLE AND ANY DISPUTES SHALL BE FINALLY SETTLED UNDER THE RULES 
//  OF ARBITRATION OF THE INTERNATIONAL CHAMBER OF COMMERCE IN THE HAGUE BY ONE OR MORE 
//  ARBITRATORS APPOINTED IN ACCORDANCE WITH SAID RULES.
//  
 
 
//  Copyright (c) 2003-2021 Xsens Technologies B.V. or subsidiaries worldwide.
//  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.  Neither the names of the copyright holders nor the names of their contributors
//      may be used to endorse or promote products derived from this software without
//      specific prior written permission.
//  
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDERS OR CONTRIBUTORS 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.THE LAWS OF THE NETHERLANDS 
//  SHALL BE EXCLUSIVELY APPLICABLE AND ANY DISPUTES SHALL BE FINALLY SETTLED UNDER THE RULES 
//  OF ARBITRATION OF THE INTERNATIONAL CHAMBER OF COMMERCE IN THE HAGUE BY ONE OR MORE 
//  ARBITRATORS APPOINTED IN ACCORDANCE WITH SAID RULES.
//  
 
#include "xbusparser.h"
#include <stdio.h>
#include <stdbool.h>
#include "xbus.h"
 
 
void XbusParser_init(XbusParser* obj, unsigned char* buffer, int bufferSize)
{
        obj->m_rxBufferSize = bufferSize;
        obj->m_rxBuffer = buffer;
        obj->m_idxWrite = 0;
        obj->m_state = haveNothing;
        obj->m_lastError = RES_Ok;
}
 
 
enum Result XbusParser_insertByte(XbusParser* obj, unsigned char byte, int* messageSize)
{
        enum Result result = RES_Ok;
        bool incrementIdxWrite = true;
 
        if (obj->m_state != haveNothing)        // if we have at least a preamble,
                obj->m_rxBuffer[obj->m_idxWrite] = byte;        // store the received byte in the buffer.
 
        switch (obj->m_state)
        {
                case haveNothing:
                        if (byte == XBUS_PREAMBLE)                              // if we have a preamble,
                        {
                                obj->m_idxWrite = 0;                                            // reset the write index
                                obj->m_rxBuffer[obj->m_idxWrite] = byte;                // store the byte
                                obj->m_state = havePreamble;                            // update our state
                                obj->m_totalLength = 1;                                 // reset m_totalLength
                                obj->m_checksum = 0;                                            // reset m_checksum
                                result = RES_FoundPreamble;
                        }
                        else
                        {
                                incrementIdxWrite = false;                      // don't increment m_idxWrite if we are not in a xbus message
                                result = RES_SpuriousByte;
                        }
                        break;
 
                case havePreamble:
                        obj->m_totalLength++;
                        obj->m_checksum += obj->m_rxBuffer[obj->m_idxWrite];
                        if (obj->m_totalLength == OFFSET_TO_LEN + 1)
                        {
                                if (obj->m_rxBuffer[obj->m_idxWrite] != LENGTH_EXTENDER_BYTE)
                                {
                                        obj->m_state = haveLength;
                                        obj->m_payloadLength = obj->m_rxBuffer[obj->m_idxWrite];
                                        obj->m_offsetToPayload = OFFSET_TO_PAYLOAD;
                                }
                                else
                                {
                                        obj->m_state = haveLengthExtenderByte;
                                        obj->m_offsetToPayload = OFFSET_TO_PAYLOAD_EXT;
                                }
                        }
                        break;
 
                case haveLengthExtenderByte:
                        obj->m_totalLength++;
                        obj->m_checksum += obj->m_rxBuffer[obj->m_idxWrite];
                        if (obj->m_totalLength == OFFSET_TO_LEN + 2)
                                obj->m_payloadLength = 256 * obj->m_rxBuffer[obj->m_idxWrite];
                        if (obj->m_totalLength == OFFSET_TO_LEN + 3)
                        {
                                obj->m_payloadLength += obj->m_rxBuffer[obj->m_idxWrite];
                                obj->m_state = haveLength;
                        }
                        break;
 
                case haveLength:
                        obj->m_totalLength++;
                        obj->m_checksum += obj->m_rxBuffer[obj->m_idxWrite];
                        if (obj->m_totalLength == (obj->m_offsetToPayload + obj->m_payloadLength + 1)) // if the current byte is the checksum
                        {
                                if ((obj->m_checksum & 0x00FF) == 0) // if checksum ok
                                        obj->m_state = haveMessage;
                                else // if checksum error,
                                {
                                        obj->m_state = haveNothing;
                                        return RES_CheckSumError;
                                }
                        }
                        break;
 
                case haveMessage:
                        break;
 
                case haveError:
                        return obj->m_lastError;
 
                default:
                        break;
        }
 
        if (obj->m_state == haveMessage)
        {
                *messageSize = obj->m_totalLength;
                return RES_MessageReceived;
        }
 
        if (incrementIdxWrite)
        {
                if (++obj->m_idxWrite >= obj->m_rxBufferSize)
                {
                        //Error condition if no packet received yet (report buffer overflow, restart ? Keep parser in error state)
                        //User must restart the parser to clear error state
                        obj->m_state = haveError;
                        obj->m_lastError = RES_BufferOverflow;
                        return obj->m_lastError;
                }
        }
 
        return result;
}