poll.c

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#include "pioLib.h"

IMPORT DAADIO	daadio;
IMPORT PIO 		pio;

void pioPoll (port, msgQId)
	int port;
	MSG_Q_ID msgQId;
	{
	PIO_MSG_Q_DATA 	msgQData;
	UINT8 			currentState;
	UINT8 			lastState[PIO_MAX_CHANNELS_PER_PORT];
	int 			channel;	
	IMPORT int 		errno;
	UINT8 *			pOutputEnablePort;

	/* Error checking */
	if (pio.initialized == FALSE)
		{
		printf ("pio not initialized\n");
		return;
		}
	/* Fail if not an input port, i.e. if the corresponding bit in the
	   output enable register is on */
	pOutputEnablePort = (UINT8 *) daadio.baseAddr + PIO_OUTPUT_ENABLE_OFFSET;
	if (*pOutputEnablePort & (1 << port))
		{
		printf ("Cannot poll an output port\n");
		return;
		}
	
	/* Initialize our record of the last state of each channel to be OFF */
	for (channel=0; channel<PIO_MAX_CHANNELS_PER_PORT; channel++)
		lastState[channel] = OFF;

	FOREVER
		{
		/* check each channel in port */
		for (channel=0; channel<PIO_MAX_CHANNELS_PER_PORT; channel++)
			{

			/* Get the current state of the channel */
			currentState = pioGet (port, channel);	

			/* Check to see if the current state differs from the state
			   of the channel the last time we checked. If it is, we
			   need to generated a message. */
			if (lastState[channel] != currentState)
				{

				/* Initialize the message structure and send it. */
				msgQData.port = port;
				msgQData.channel = channel;
				msgQData.state = currentState;
				msgQData.timeStamp = tickGet();	

				if (msgQSend (msgQId, &msgQData, sizeof (PIO_MSG_Q_DATA),
								 NO_WAIT, MSG_PRI_NORMAL) == ERROR)
					{

					/* If failure was because queue is full, just print
					   warning and continue. Any other failure, print
					   message and terminate. */

					if (errno == S_objLib_OBJ_UNAVAILABLE)
						printf ("Msg Queue full: dumping data for port %d, channel %d, status is %s at clock tick %d\n", port, channel, (currentState) ? "ON" :
								"OFF", msgQData.timeStamp);
					else
						{
						printf ("Msg Queue fatal error: aborting poll task\n");
						return;
						}
					}
				
				/* Update our record of the last state for this channel. */
				lastState[channel] = currentState;
				}
			taskDelay (PIO_POLL_DELAY);
			}
		}
	}