piolib.c

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#include "pioLib.h"

IMPORT DAADIO daadio;
PIO pio;

STATUS pioInit (outputEnableMask)
	UINT8 outputEnableMask;	/* Mask to set which are output ports */
	{
	UINT8 *	pOutputEnablePort;
	int 	port;
	UINT8 *	pPort;

	/* If daadioInit() has not been called, fail */
	if (daadio.initialized == FALSE)
		{
		printf ("daadio not initialized\n");
		return (ERROR);
		}

	/* If mutex semaphore has not been created, do it now */
	if (pio.mutexSem == NULL)
		{
		if ((pio.mutexSem = semMCreate (SEM_Q_PRIORITY|SEM_DELETE_SAFE|
									SEM_INVERSION_SAFE)) == NULL)
			return (ERROR);
		}

	/* Initialize <pOutputEnablePort> to point to the output enable register */
	pOutputEnablePort = (UINT8 *)daadio.baseAddr + 
						PIO_OUTPUT_ENABLE_OFFSET;

	/* Set the output enable register to the mask the user passed us */
	*pOutputEnablePort = outputEnableMask;

	/* Reset all output channels */
	for (port=0; port<PIO_MAX_PORTS; port++, outputEnableMask>>=1)
		{
		if (outputEnableMask & 1) 
			{
			pPort = (UINT8 *) daadio.baseAddr + PIO_PORT_NUM_TO_OFF (port);
			*pPort = (UINT8)0;
			}
		}

	pio.initialized = TRUE;

	return (OK);
	}

STATUS pioSet (port, channel, state)
	int port, channel;
	BOOL state;
	{
	UINT8 *pPort;	/* pointer to port register */
	int channelBit;	/* bit which reflect which channel is being set */

	/* Error checking...
	 * Ensure pioInit() routine has been called 
	 * and the port and channel are within range.
	 */
	
	if (pio.initialized == FALSE)
		{
		printf ("pio not initialized\n");
		return (ERROR);
		}

	if (port < 0 || port >= PIO_MAX_PORTS)
		{
		printf ("port number out of range\n");
		return (ERROR);
		}

	if (channel < 0 || channel >= PIO_MAX_CHANNELS_PER_PORT)
		{
		printf ("channel number out of range\n");
		return (ERROR);
		}

	if ((*((UINT8 *)daadio.baseAddr + PIO_OUTPUT_ENABLE_OFFSET) & (1 << port)) 
		== 0)
		{
		printf ("can not set an input port\n");
		return (ERROR);
		}
	
	/* Initialize <pPort> to point to the appropriate port */
	pPort = (UINT8 *) daadio.baseAddr +  PIO_PORT_NUM_TO_OFF (port);

	/* Set a bit in <channelBit> which reflects which channel is being set, 
	   i.e. if channel 0, set bit 0; if channel 1, set bit 1; and so on. */
	channelBit = 1 << channel;

	/* Update the port register pointed to by <pPort> to be set or unset
	   based on the value of <state>. Since this is a read/modify/write
	   operation, mutual exclusion needs to be assured. */
	if (semTake (pio.mutexSem, WAIT_FOREVER) == ERROR)
		return (ERROR);
	if (state)
		*pPort |=  channelBit;
	else
		*pPort &= ~channelBit;
	semGive (pio.mutexSem);
	
	return (OK);
	}

int pioGet (port, channel)
	int port, channel;
	{
	UINT8 *pPort;	/* pointer to port register */
	int channelBit;	/* bit which reflects which channel is being tested */
	BOOL state;		/* whether channel is ON or OFF */

	/* Error checking...
	 * Ensure that pioInit() routine has been called 
	 * and the port and channel are within range.
	 */
	
	if (pio.initialized == FALSE)
		{
		printf ("pio not initialized\n");
		return (ERROR);
		}

	if (port < 0 || port >= PIO_MAX_PORTS)
		{
		printf ("port number out of range\n");
		return (ERROR);
		}

	if (channel < 0 || channel >= PIO_MAX_CHANNELS_PER_PORT)
		{
		printf ("channel number out of range\n");
		return (ERROR);
		}
	
	/* Initialize <pPort> to point to the appropriate port */
	pPort = (UINT8 *) daadio.baseAddr +  PIO_PORT_NUM_TO_OFF (port);

	/* Set a bit in <channelBit> which reflects which channel is being set, 
	   i.e. if channel 0, set bit 0; if channel 1, set bit 1; and so on. */
	channelBit = 1 << channel;

	/* Set <state> to be ON or OFF depending on the state of the channel */
	state = (*pPort & channelBit) ? ON : OFF;	

	return (state);
	}