I'm writing to some serial comm port with specific bytes set into buffer. My protocol for write buffer is written below. Platform is Windows and IDE is Visual C++.

1. Byte 0 will have message type indicator (Byte)
2. Byte 1-4 will have message number (Uint32)
3. Byte 5-8 will have unix epoc time (Uint32)
4. Byte 13-14 will have number of sample packets (Uint16)
5. Bytes 15+ (upto 60) will have sample data packets (Uint16)
6. Byte 15+(No of samples*2) will have end of message (Byte)

Now I'm concern about buffer building (raw Bytes) from integer or short values. Please have a look at the below code.

void ConvertIntToByte(int iValue, BYTE* ucRawBuffer, int iOffset)
{
  ucRawBuffer[iOffset]   = ((iValue >> 24) & 0xFF);
  ucRawBuffer[iOffset+1] = ((iValue >> 16) & 0xFF);
  ucRawBuffer[iOffset+2] = ((iValue >> 8) & 0xFF);
  ucRawBuffer[iOffset+3] = (iValue & 0xFF);
}

void ConvertShortToByte(short iValue, BYTE* ucRawBuffer, int iOffset)
{
  ucRawBuffer[iOffset]   = (iValue >> 8) & 0xFF;
  ucRawBuffer[iOffset+1] = iValue & 0xFF;
}

void DataThreadFunction()
{
  while(!m_bClosed)
  {
    DWORD dwRet = WaitForSingleObject(m_hDataSendEvent, INFINITE);
    if(dwRet == WAIT_OBJECT_0)
    {
      ResetEvent(m_hDataSendEvent);

      int iUTCTime = GetEpochTime();
      m_iMsgSequence++;
      ASSERT(m_iMaxSamples != 0);

      BYTE ucXmtdat[60] = {0};
      ucXmtdat[0] = 0x0B;
      ConvertIntToByte(iUTCTime, ucXmtdat, 1);
      ConvertIntToByte(m_iMsgSequence, ucXmtdat, 5);
      ConvertIntToByte(m_iMaxSamples, ucXmtdat, 13);
      int iOffset = 15;
      // m_data - member vector populating from some other method
      for(unsigned int i = 0; i < m_data.size(); i++)
      {
        short iCurrData = m_data[i];
        ConvertShortToByte(iCurrData, ucXmtdat, iOffset);
        iOffset += sizeof(unsigned short);
      }

      m_data.clear();
      iOffset = 15+(m_iMaxSamples*2);
      ucXmtdat[iOffset] = 0xCA;

      bool bSuccess = m_objComm.WriteCommPort(ucXmtdat, 60);
    }
  }
}

I'm writing to some serial comm port with specific bytes set into buffer. My protocol for write buffer is written below. Platform is Windows and IDE is Visual C++.

1. Byte 0 will have message type indicator (Byte)
2. Byte 1-4 will have message number (Uint32)
3. Byte 5-8 will have unix epoch time (Uint32)
4. Byte 13-14 will have number of sample packets (Uint16)
5. Bytes 15+ (upto 60) will have sample data packets (Uint16)
6. Byte 15+(No of samples*2) will have end of message (Byte)

Now I'm concern about buffer building (raw Bytes) from integer or short values.

void ConvertIntToByte(int iValue, BYTE* ucRawBuffer, int iOffset)
{
  ucRawBuffer[iOffset]   = ((iValue >> 24) & 0xFF);
  ucRawBuffer[iOffset+1] = ((iValue >> 16) & 0xFF);
  ucRawBuffer[iOffset+2] = ((iValue >> 8) & 0xFF);
  ucRawBuffer[iOffset+3] = (iValue & 0xFF);
}

void ConvertShortToByte(short iValue, BYTE* ucRawBuffer, int iOffset)
{
  ucRawBuffer[iOffset]   = (iValue >> 8) & 0xFF;
  ucRawBuffer[iOffset+1] = iValue & 0xFF;
}

void DataThreadFunction()
{
  while(!m_bClosed)
  {
    DWORD dwRet = WaitForSingleObject(m_hDataSendEvent, INFINITE);
    if(dwRet == WAIT_OBJECT_0)
    {
      ResetEvent(m_hDataSendEvent);

      int iUTCTime = GetEpochTime();
      m_iMsgSequence++;
      ASSERT(m_iMaxSamples != 0);

      BYTE ucXmtdat[60] = {0};
      ucXmtdat[0] = 0x0B;
      ConvertIntToByte(iUTCTime, ucXmtdat, 1);
      ConvertIntToByte(m_iMsgSequence, ucXmtdat, 5);
      ConvertIntToByte(m_iMaxSamples, ucXmtdat, 13);
      int iOffset = 15;
      // m_data - member vector populating from some other method
      for(unsigned int i = 0; i < m_data.size(); i++)
      {
        short iCurrData = m_data[i];
        ConvertShortToByte(iCurrData, ucXmtdat, iOffset);
        iOffset += sizeof(unsigned short);
      }

      m_data.clear();
      iOffset = 15+(m_iMaxSamples*2);
      ucXmtdat[iOffset] = 0xCA;

      bool bSuccess = m_objComm.WriteCommPort(ucXmtdat, 60);
    }
  }
}