/// <summary>
/// Reads a string up to the specified <i>text</i> in the input buffer.
/// </summary>
/// <remarks>
/// The ReadTo() function will read text from the byte buffer up to a predetermined
/// limit (1024 characters) when looking for the string <i>text</i>. If <i>text</i>
/// is not found within this limit, data is thrown away and more data is read
/// (effectively consuming the earlier bytes).
/// <para>this method is provided as compatibility with the Microsoft implementation.
/// There are some important differences however. This method attempts to fix a minor
/// pathological problem with the Microsoft implementation. If the string <i>text</i>
/// is not found, the MS implementation may modify the internal state of the decoder.
/// As a workaround, it pushes all decoded characters back into its internal byte
/// buffer, which fixes the problem that a second call to the ReadTo() method returns
/// the consistent results, but a call to Read(byte[], ..) may return data that was
/// not actually transmitted by the DCE. This would happen in case that an invalid
/// byte sequence was found, converted to a fallback character. The original byte
/// sequence is removed and replaced with the byte equivalent of the fallback
/// character.</para>
/// <para>This method is rather slow, because it tries to preserve the byte buffer
/// in case of failure. If your application works entirely by using character
/// sequences, you may get much better performance by using Read(char[], ...) and
/// searching for string sequences yourself, as Read(char[], ...) does a complete
/// conversion bytes to characters in as few steps as possible.</para>
/// </remarks>
/// <param name="text">The text to indicate where the read operation stops.</param>
/// <returns>The contents of the input buffer up to the specified <i>text</i>.</returns>
public string ReadTo(string text)
{
if (IsDisposed) throw new ObjectDisposedException("SerialPortStream");
if (string.IsNullOrEmpty(text)) throw new ArgumentException("Parameter text shall not be null or empty", "text");
// Decoders in .NET are designed for streams and not really for reading
// a little bit of data. By design, they are "greedy", they consume as much
// byte data as possible. The data that they consume is cached internally.
// Because it's not possible to ask the decoder only to decode if there
// is sufficient bytes, we have to keep account of how many bytes are
// consumed for each character.
// Hence, m_ReadIncomplete tells us if we've consumed bytes, but have not
// yet received a converted character.
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: BEGIN");
bool changedtext = !text.Equals(m_ReadToString);
if (changedtext) {
// Last search might have had a read overflow and we're now looking for a different
// string. So we need to reset our buffer and start from the beginning
ReadToOverflowCheck();
}
int readlen = m_Read.Length - (m_ReadIncomplete ? 1 : 0);
if (changedtext && readlen >= text.Length) {
// Check if the text already exists
string lbuffer = m_Read.GetString(readlen);
int p = lbuffer.IndexOf(text, StringComparison.Ordinal);
if (p != -1) {
// It does exist, so consume up to the buffered portion
string result = lbuffer.Substring(0, p);
int l = p + text.Length;
ReadToConsume(l);
return result;
}
}
TimerExpiry te = new TimerExpiry(m_ReadTimeout);
while (!ReadToMatch(text)) {
int bytesRead;
int c = m_SerialPort.SerialPortIo.PeekChar(m_ReadOffset, Decoder, out bytesRead);
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: c = {0} = PeekChar(m_ReadOffset={1}, Decoder, out bytesRead={2})", c, m_ReadOffset, bytesRead);
if (c != -1) {
if (m_ReadIncomplete) {
int lb = m_Read.Length - 1;
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: m_ReadIncomplete == true; m_Read[{0}]={1}; m_ReadOffsets[{0}]={2}", lb, (char)c, m_ReadOffsets[lb]);
m_Read[lb] = (char)c;
m_ReadOffsets[lb] += bytesRead;
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: m_ReadIncomplete == true; m_Read[{0}]={1}; m_ReadOffsets[{0}]={2}", lb, (char)c, m_ReadOffsets[lb]);
} else {
if (m_Read.Free == 0) {
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_ReadIncomplete == false; m_Read.Free==0");
// Discard the oldest character in preference for the newer character
if (m_ReadOverflow == -1) {
// Overflow. We capture the first byte, because we'll have to reset the decoder later
m_ReadOverflowChar = m_Read[0];
m_ReadOverflow = m_ReadOffsets[0];
}
m_Read.Consume(1);
m_ReadOffsets.Consume(1);
}
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: m_ReadIncomplete == false; m_Read.Append({0}); m_ReadOffsets.Append({1})", (char)c, bytesRead);
m_Read.Append((char)c);
m_ReadOffsets.Append(bytesRead);
}
m_ReadOffset += bytesRead;
m_ReadIncomplete = false;
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_ReadOffset = {0}", m_ReadOffset);
} else {
if (bytesRead > 0) {
if (!m_ReadIncomplete) {
// The decoder consumed bytes, even though we don't have a character
if (m_Read.Free == 0) {
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_ReadIncomplete == false; m_Read.Free == 0");
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_Read.Consume(1)");
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_ReadOffset = {0} - {1}", m_ReadOffset, m_ReadOffsets[0]);
// Discard the oldest character in preference for the newer character
if (m_ReadOverflow == -1) {
// Overflow. We capture the first byte, because we'll have to reset the decoder later
m_ReadOverflowChar = m_Read[0];
m_ReadOverflow = m_ReadOffsets[0];
}
m_Read.Consume(1);
m_ReadOffsets.Consume(1);
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_ReadOffset = {0}", m_ReadOffset);
}
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: m_ReadIncomplete == false; m_Read.Free == {0}", m_Read.Free);
m_Read.Append((char)0);
m_ReadOffsets.Append(bytesRead);
m_ReadOffset += bytesRead;
m_ReadIncomplete = true;
} else {
int lb = m_Read.Length - 1;
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: m_ReadIncomplete == true; m_ReadOffsets[{0}]={1}", lb, m_ReadOffsets[lb]);
m_ReadOffsets[lb] += bytesRead;
m_ReadOffset += bytesRead;
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: m_ReadIncomplete == true; m_ReadOffsets[{0}]={1}", lb, m_ReadOffsets[lb]);
}
} else {
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0,
"ReadTo: WaitForReadEvent({0}, {1})", m_ReadOffset + 1, te.RemainingTime());
// Need to wait for the next byte
if (!m_SerialPort.SerialPortIo.WaitForReadEvent(m_ReadOffset + 1, te.RemainingTime())) {
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: TIMEOUT");
// Remember the string for the next timeout
m_ReadToString = text;
throw new TimeoutException();
}
}
}
}
m_SerialPort.SerialPortIo.DiscardInBuffer(m_ReadOffset);
string rbuffer = m_Read.GetString();
rbuffer = rbuffer.Substring(0, m_Read.Length - text.Length);
ReadToReset();
m_TraceRT.TraceEvent(System.Diagnostics.TraceEventType.Verbose, 0, "ReadTo: RESULT = {0}", rbuffer);
return rbuffer;
}
/// <summary>
/// Synchronously reads one character from the SerialPortStream input buffer.
/// </summary>
/// <returns>The character that was read. -1 indicates no data was available
/// within the timeout.</returns>
public int ReadChar()
{
if (IsDisposed) throw new ObjectDisposedException("SerialPortStream");
// Dealing with cached characters read by the ReadTo() method
ReadToOverflowCheck();
if (IsReadToBuffered()) {
// Check there is at least one valid byte. if the condition:
// (m_ReadIncomplete == true && m_Read.Length == 1 || m_Read.Length < 1)
// then there are no valid bytes available.
if (!m_ReadIncomplete || m_Read.Length > 1) {
int value = m_Read[0];
ReadToConsume(1);
return value;
}
}
ReadToReset();
// Reading data from the byte buffer
TimerExpiry t = new TimerExpiry(m_ReadTimeout);
int timeout = m_ReadTimeout;
do {
if (!m_SerialPort.SerialPortIo.WaitForReadEvent(timeout)) return -1;
int c = m_SerialPort.SerialPortIo.ReadChar(this.Decoder);
if (c != -1) return c;
timeout = t.RemainingTime();
} while (timeout > 0);
return -1;
}
/// <summary>
/// Wait for sufficient buffer space to be available in the write buffer within a timeout.
/// </summary>
/// <param name="count">The number of bytes that should be available.</param>
/// <param name="timeout">The timeout in milliseconds.</param>
/// <returns><b>true</b> if there is at least <c>count</c> bytes available in the write
/// buffer within <c>timeout</c> milliseconds. <b>false</b> is always returned if no
/// buffers have been allocated or if the serial thread isn't running (without a timeout).
/// </returns>
public bool WaitForWriteEvent(int count, int timeout)
{
if (m_Buffers == null || !IsRunning) return false;
int free;
lock (m_WriteLock) {
// If we can't write the entire buffer to the WRITE buffer, we should wait
free = m_Buffers.WriteBuffer.Free;
if (free < count) m_WriteBufferNotFullEvent.Reset();
}
// Wait until we can write the full amount of data to the buffer
TimerExpiry exp = new TimerExpiry(timeout);
while (free < count) {
if (!m_WriteBufferNotFullEvent.WaitOne(exp.RemainingTime())) {
return false;
} else {
lock (m_WriteLock) {
// If we can't write the entire buffer to the WRITE buffer, we should wait
free = m_Buffers.WriteBuffer.Free;
if (free < count) m_WriteBufferNotFullEvent.Reset();
}
}
}
return true;
}
/// <summary>
/// Reads a number of characters from the SerialPortStream input buffer and writes
/// them into an array of characters at a given offset.
/// </summary>
/// <remarks>
/// This function converts the data in the local buffer to characters based on the
/// encoding defined by the encoding property. The encoder used may buffer data between
/// calls if characters may require more than one byte of data for its interpretation
/// as a character.
/// </remarks>
/// <param name="buffer">The character array to write the input to.</param>
/// <param name="offset">Offset into the buffer where to start putting the data.</param>
/// <param name="count">Maximum number of bytes to read into the buffer.</param>
/// <returns>The actual number of bytes copied into the buffer, 0 if there was a timeout.</returns>
public int Read(char[] buffer, int offset, int count)
{
if (IsDisposed) throw new ObjectDisposedException("SerialPortStream");
if (buffer == null) throw new ArgumentNullException("buffer", "NULL buffer provided");
if (offset < 0) throw new ArgumentOutOfRangeException("offset", "Negative offset provided");
if (count < 0) throw new ArgumentOutOfRangeException("count", "Negative count provided");
if (buffer.Length - offset < count) throw new ArgumentException("offset and count exceed buffer boundaries");
if (count == 0) return 0;
// Dealing with cached characters read by the ReadTo() method
int cached = 0;
ReadToOverflowCheck();
if (IsReadToBuffered()) {
int readlen = Math.Min(count, m_Read.Length - (m_ReadIncomplete ? 1 : 0));
if (readlen > 0) {
cached = m_Read.CopyTo(buffer, offset, readlen);
ReadToConsume(cached);
if (cached == count) {
// Read operation is complete, may/may not be data in the cache
return cached;
}
offset += cached;
count -= cached;
// If there are no bytes in the serial driver, we don't need to wait
if (m_SerialPort.SerialPortIo.BufferedBytesToRead == 0) return cached;
}
}
ReadToReset();
// Obtaining bytes from our buffered I/O thread
TimerExpiry t = new TimerExpiry(m_ReadTimeout);
int timeout = m_ReadTimeout;
do {
if (!m_SerialPort.SerialPortIo.WaitForReadEvent(timeout)) return 0;
int c = m_SerialPort.SerialPortIo.Read(buffer, offset, count, this.Decoder);
if (c > 0) return c;
timeout = t.RemainingTime();
} while (timeout > 0);
return 0;
}
/// <summary>
/// Wait for there to be at least <i>bytes</i> by a timeout.
/// </summary>
/// <param name="bytes">Number of bytes expected to be in the input buffer</param>
/// <param name="timeout">Timeout in milliseconds</param>
/// <returns><b>true</b> if there is at least <i>bytes</i> number of data in the
/// read buffer. <b>false</b> if there is not enough data within the timeout
/// specified.</returns>
public bool WaitForReadEvent(int bytes, int timeout)
{
if (IsRunning) {
TimerExpiry te = new TimerExpiry(timeout);
while (true) {
lock (m_ReadLock) {
if (m_Buffers.ReadBuffer.Length >= bytes) return true;
m_ReadBufferEvent.Reset();
}
if (!m_ReadBufferEvent.WaitOne(timeout)) return false;
timeout = te.RemainingTime();
}
} else {
if (m_Buffers == null) return false;
if (m_Buffers.ReadBuffer.Length < bytes) {
// No data in the buffer to read. No need to timeout, as we're not running
// and therefore don't expect more data
return false;
}
}
return true;
}
