pip_lio.c

Using DSP/BIOS I/O in Multichannel Systems

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/*
 *  ======== pip_lio.c ========
 *! Revision History
 *! ================
 */

#include <std.h>
#include <log.h>
#include <swi.h>
#include <pip.h>

#include <lio.h>

extern LIO_Fxns PIP_LIO_FXNS;
LIO_Fxns *drv = &PIP_LIO_FXNS;

Void PIP_LIO_txPrime(int chan, PIP_Obj *pip);
Void PIP_LIO_rxPrime(int chan, PIP_Obj *pip);

#define RCV_CHAN0 0
#define XMT_CHAN0 1
#define RCV_CHAN1 2
#define XMT_CHAN1 3

/* forward decl */
extern Void PIP_LIO_rxPump(Uns, Arg);
extern Void PIP_LIO_txPump(Uns, Arg);

extern far PIP_Obj txPip0;
extern far PIP_Obj rxPip0;
extern far PIP_Obj txPip1;
extern far PIP_Obj rxPip1;

Void
PIP_LIO_init(Void)
{
	drv->init(RCV_CHAN0, NULL);
	drv->init(XMT_CHAN0, NULL);
	drv->init(RCV_CHAN1, NULL);
	drv->init(XMT_CHAN1, NULL);

	drv->setCallback(RCV_CHAN0, PIP_LIO_rxPump, (Arg)&rxPip0);
	drv->setCallback(XMT_CHAN0, PIP_LIO_txPump, (Arg)&txPip0);
	drv->setCallback(RCV_CHAN1, PIP_LIO_rxPump, (Arg)&rxPip1);
	drv->setCallback(XMT_CHAN1, PIP_LIO_txPump, (Arg)&txPip1);

	drv->start(RCV_CHAN0);
	drv->start(XMT_CHAN0);
	drv->start(RCV_CHAN1);
	drv->start(XMT_CHAN1);

	/* PENDING: Do I really need to call these here? */
    /* these enable interrupts, maybe a problem? */
    /* PIP_LIO_txPrime(XMT_CHAN, txPip); */
    /* PIP_LIO_rxPrime(RCV_CHAN, rxPip); */
}

/* LIO callback for transmit channels */
Void
PIP_LIO_txPump(Uns chan, Arg parg)
{
	PIP_Obj *pip = (PIP_Obj *)parg;
	
	if (drv->getBuf(chan, NULL, NULL) != NULL) {
		PIP_free(pip);
		/* push another buffer into the hardware queue if available */
		PIP_LIO_txPrime(chan, pip);
	}

}

/*
 *  ======= PIP_LIO_txPrime ========
 *  This must be called  by the notifyReader function of the txPips
 */
Void
PIP_LIO_txPrime(int chan, PIP_Obj *pip)
{
	static int nested = 0;

	if (nested) return;

	nested = 1;

	/* if there is room in the driver and a frame on the tx queue */

	/* PENDING: There is a race condition between !isEmpty and nested =
       0. If the callback occurs after isEmpty returns false but before
       nested = 0 then a new buffer will not be put into the hw queue
       and the system will deadlock. We need to turn off interrupts
       here. SWI callbacks would have made this easier I think. We could
       replace HWI_disable with drv->disable perhaps. */
	HWI_disable();
	/* must ensure isEmpty, can only operate on one PIP frame at a time */
	if (drv->isEmpty(chan) && PIP_getReaderNumFrames(pip) > 0) {
		HWI_enable();
		/* pull it off of the pipe and put it on the hardware queue */
	    PIP_get(pip);
	    drv->setBuf(chan,
					PIP_getReaderAddr(pip),
					PIP_getReaderSize(pip)*sizeof(int)); /* words to bytes */
	} else {
		HWI_enable();
	}

	nested = 0;
}

/* LIO callback for receive channels */
Void
PIP_LIO_rxPump(Uns chan, Arg parg)
{
	PIP_Obj *pip = (PIP_Obj *)parg;
	int validWords;
	
	if (drv->getBuf(chan, NULL, &validWords)) {
		validWords = validWords/sizeof(int); /* convert from bytes to words */
		PIP_setWriterSize(pip, validWords);
		PIP_put(pip);

		/* We know a buffer just came out of the hw queue, so try to
		   put another in. */
		PIP_LIO_rxPrime(chan, pip);
	}
}

/*
 *  ======= DSS_rxPrime ========
 *  This must be the notifyWriter function of the rxPips
 */
void
PIP_LIO_rxPrime(int chan, PIP_Obj *pip)
{
	static int nested = 0;

	if (nested) return;
	nested = 1;
	
	/* if there is a frame on the rx queue */

	/* PENDING: There is a race condition between !isFull and nested =
       0. If the callback occurs after isFull returns false but before
       nested = 0 then a new buffer will not be put into the hw queue
       and the system will deadlock. We need to turn off interrupts
       here. SWI callbacks would have made this easier I think. We could
       replace HWI_disable with drv->disable perhaps. */
	HWI_disable();
	if (drv->isEmpty(chan) && PIP_getWriterNumFrames(pip) > 0) {
		HWI_enable();
	    PIP_alloc(pip);
	    drv->setBuf(chan,
					PIP_getWriterAddr(pip),
					PIP_getWriterSize(pip)*sizeof(int)); /* words to bytes */
	} else {
		HWI_enable();
	}


	nested = 0;
}