private void PerformWriteRead(SerialPort com1, SerialPort com2, byte[] xmitBytes, byte[] expectedBytes)
{
byte[] rcvBytes = new byte[expectedBytes.Length * 4];
Stopwatch sw = new Stopwatch();
double expectedTime, actualTime, percentageDifference;
int numParityBits = (Parity)com1.Parity == Parity.None ? 0 : 1;
double numStopBits = GetNumberOfStopBits(com1);
int length = xmitBytes.Length;
int rcvLength;
// TODO: Consider removing all of the code to check the time it takes to transfer the bytes.
// This was likely just a copy and paste from another test case
actualTime = 0;
Thread.CurrentThread.Priority = ThreadPriority.Highest;
for (int i = 0; i < NUM_TRYS; i++)
{
com2.DiscardInBuffer();
IAsyncResult beginWriteResult = com1.BaseStream.BeginWrite(xmitBytes, 0, length, null, null);
while (0 == com2.BytesToRead)
{
;
}
sw.Start();
// Wait for all of the bytes to reach the input buffer of com2
TCSupport.WaitForReadBufferToLoad(com2, length);
sw.Stop();
actualTime += sw.ElapsedMilliseconds;
com1.BaseStream.EndWrite(beginWriteResult);
sw.Reset();
}
Thread.CurrentThread.Priority = ThreadPriority.Normal;
actualTime /= NUM_TRYS;
expectedTime = ((xmitBytes.Length * (1 + numStopBits + com1.DataBits + numParityBits)) / com1.BaudRate) * 1000;
percentageDifference = Math.Abs((expectedTime - actualTime) / expectedTime);
//If the percentageDifference between the expected time and the actual time is to high
//then the expected baud rate must not have been used and we should report an error
if (MAX_ACCEPTABEL_PERCENTAGE_DIFFERENCE < percentageDifference)
{
Fail("ERROR!!! Parity not used Expected time:{0}, actual time:{1} percentageDifference:{2}", expectedTime, actualTime, percentageDifference);
}
rcvLength = com2.Read(rcvBytes, 0, rcvBytes.Length);
if (0 != com2.BytesToRead)
{
Fail("ERROR!!! BytesToRead={0} expected 0", com2.BytesToRead);
}
//Verify that the bytes we sent were the same ones we received
int expectedIndex = 0, actualIndex = 0;
for (; expectedIndex < expectedBytes.Length && actualIndex < rcvBytes.Length; ++expectedIndex, ++actualIndex)
{
if (expectedBytes[expectedIndex] != rcvBytes[actualIndex])
{
if (actualIndex != rcvBytes.Length - 1 && expectedBytes[expectedIndex] == rcvBytes[actualIndex + 1])
{
//Sometimes if there is a parity error an extra byte gets added to the input stream so
//look ahead at the next byte
actualIndex++;
}
else
{
Debug.WriteLine("Bytes Sent:");
TCSupport.PrintBytes(xmitBytes);
Debug.WriteLine("Bytes Received:");
TCSupport.PrintBytes(rcvBytes);
Debug.WriteLine("Expected Bytes:");
TCSupport.PrintBytes(expectedBytes);
Fail(
"ERROR: Expected to read {0,2:X} at {1,3} actually read {2,2:X} sent {3,2:X}",
expectedBytes[expectedIndex],
expectedIndex,
rcvBytes[actualIndex],
xmitBytes[expectedIndex]);
}
}
}
if (expectedIndex < expectedBytes.Length)
{
Fail("ERRROR: Did not enumerate all of the expected bytes index={0} length={1}", expectedIndex, expectedBytes.Length);
}
}
