implement parsing of header of message
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2 changed files with 94 additions and 6 deletions
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@ -12,7 +12,7 @@ Protocol message definition
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+-----------+------------+-----------------+--------------+-------------+
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+-----------+------------+-----------------+--------------+-------------+
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- message ID defined by the defines PROTMESSID_x
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- message ID defined by the defines PROTMESSID_x
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- cnt: counter which is incremet for each message and wraps around at 255
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- cnt: counter which is increment for each message and wraps around at 255
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- length n in bytes of the data
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- length n in bytes of the data
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- actual data, dependent on message type
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- actual data, dependent on message type
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- 16 bits CRC, calculating over the entire message, is transmitted inverted
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- 16 bits CRC, calculating over the entire message, is transmitted inverted
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@ -41,5 +41,86 @@ Protocol message definition
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/* Implementation *************************************************************/
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/* Implementation *************************************************************/
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// TODO
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#define MESS_HEADER_LENGTH_BYTE 5 /* ID, cnt, length */
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#define MESS_LEN_WITHOUT_DATA_BYTE ( MESS_HEADER_LENGTH_BYTE + 2 /* CRC */ )
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bool CProtocol::ParseMessage ( const CVector<uint8_t>& vecIn )
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{
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/*
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return code: true -> ok; false -> error
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*/
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int iID, iCnt, iLenBy, i;
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unsigned int iCurPos;
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// query length of input vector
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const int iVecInLenByte = vecIn.Size();
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// vector must be at least "MESS_LEN_WITHOUT_DATA_BYTE" bytes long
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if ( iVecInLenByte < MESS_LEN_WITHOUT_DATA_BYTE )
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{
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return false; // return error code
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}
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// decode header -----
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iCurPos = 0; // start from beginning
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for ( i = 0; i < MESS_HEADER_LENGTH_BYTE; i++ )
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{
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/* 2 bytes ID */
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iID = static_cast<int> ( GetValFromStream ( vecIn, iCurPos, 2 ) );
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/* 1 byte cnt */
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iCnt = static_cast<int> ( GetValFromStream ( vecIn, iCurPos, 1 ) );
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/* 2 bytes length */
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iLenBy = static_cast<int> ( GetValFromStream ( vecIn, iCurPos, 2 ) );
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}
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// make sure the length is correct
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if ( iLenBy != iVecInLenByte - MESS_LEN_WITHOUT_DATA_BYTE )
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{
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return false; // return error code
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}
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// now check CRC -----
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CCRC CRCObj;
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iCurPos = 0; // start from beginning
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const int iLenCRCCalc = MESS_HEADER_LENGTH_BYTE + iLenBy;
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for ( i = 0; i < iLenCRCCalc; i++ )
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{
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CRCObj.AddByte ( static_cast<uint8_t> (
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GetValFromStream ( vecIn, iCurPos, 1 ) ) );
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}
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if ( CRCObj.GetCRC () != GetValFromStream ( vecIn, iCurPos, 2 ) )
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{
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return false; // return error code
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}
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// TODO actual parsing of message data
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return true; // everything was ok
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}
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uint32_t CProtocol::GetValFromStream ( const CVector<uint8_t>& vecIn,
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unsigned int& iPos,
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const unsigned int iNumOfBytes )
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{
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/*
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note: iPos is automatically incremented in this function
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*/
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// 4 bytes maximum since we return uint32
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ASSERT ( ( iNumOfBytes > 0 ) && ( iNumOfBytes <= 4 ) );
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ASSERT ( vecIn.Size() >= iPos + iNumOfBytes );
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uint32_t iRet = 0;
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for ( int i = 0; i < iNumOfBytes; i++ )
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{
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iRet |= vecIn[iPos + i] << ( i * 8 /* size of byte */ );
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}
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return iRet;
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}
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@ -24,8 +24,10 @@
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#if !defined(PROTOCOL_H__3B123453_4344_BB2392354455IUHF1912__INCLUDED_)
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#if !defined(PROTOCOL_H__3B123453_4344_BB2392354455IUHF1912__INCLUDED_)
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#define PROTOCOL_H__3B123453_4344_BB2392354455IUHF1912__INCLUDED_
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#define PROTOCOL_H__3B123453_4344_BB2392354455IUHF1912__INCLUDED_
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#include "global.h"
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#include <qglobal.h>
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#include "global.h"
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#include "util.h"
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/* Definitions ****************************************************************/
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/* Definitions ****************************************************************/
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@ -39,11 +41,16 @@
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class CProtocol
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class CProtocol
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{
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{
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public:
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public:
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CProtocol() {}
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CProtocol() : iCounter(0) {}
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virtual ~CProtocol() {}
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virtual ~CProtocol() {}
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protected:
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protected:
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bool ParseMessage ( const CVector<uint8_t>& vecIn );
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uint32_t GetValFromStream ( const CVector<uint8_t>& vecIn,
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unsigned int& iPos,
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const unsigned int iNumOfBytes );
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uint8_t iCounter;
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};
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};
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class CServerProtocol : public CProtocol
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class CServerProtocol : public CProtocol
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