Apple16X50Queue.h   [plain text]


/*
Copyright (c) 1997-2002 Apple Computer, Inc. All rights reserved.
Copyright (c) 1994-1996 NeXT Software, Inc.  All rights reserved.
 
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*/

/*
 * 1995-06-28	dreece	Created
 * 2002-03-05	dreece	I/O Kit port, based on drvISASerialPort:queue_primatives.m.
 */

#ifndef _APPLEPCI16X50QUEUE_H
#define _APPLEPCI16X50QUEUE_H

#include "Apple16X50Serial.h"
#include <IOKit/serial/IOSerialStreamSync.h>

#define BIGGEST_EVENT		((UInt32)3)
#define QUEUE_SIZE_MINIMUM	((UInt32)64)
#define QUEUE_SIZE_DEFAULT	((UInt32)2048)
#define QUEUE_SIZE_MAXIMUM	((UInt32)32768)

enum tQueueState {
    kQueueEmpty = (PD_S_TXQ_EMPTY | PD_S_TXQ_LOW_WATER), // 0 events in queue
    kQueueLow = PD_S_TXQ_LOW_WATER,	// 1..(LowWater-1) events in queue
    kQueueMedium = 0,			// LowWater..(HighWater-1) events in queue
    kQueueHigh = PD_S_TXQ_HIGH_WATER,	// HighWater..(Size-1) events in queue
    kQueueFull = (PD_S_TXQ_HIGH_WATER | PD_S_TXQ_FULL)	// Size events in queue
};

enum tDirection { kRxQ, kTxQ };

class Apple16X50Queue
{
public:
    Apple16X50Queue(tDirection dir); // constructor
    ~Apple16X50Queue();		     // destructor
    
    UInt32	HighWater;	// high water mark in chars
    UInt32	LowWater;	// low water mark in chars
    UInt32	Size;		// maximum number of chars in queue
    UInt32	Count;		// current number of chars in queue

    void	setSize(UInt32 size=QUEUE_SIZE_DEFAULT);
    void	setLowWater(UInt32 low=0);
    void	setHighWater(UInt32 high=0);
    inline bool	enqueueThresholdExceeded() { return (Count > EnqueueThreshold); };
    inline bool	dequeueThresholdExceeded() { return (Count < DequeueThreshold); };
    void	flush();
    tQueueState getState();

    void	enqueueEvent(UInt8 event, UInt32 data=0);
    bool	enqueueEventTry(UInt8 event, UInt32 data=0);
    UInt8	dequeueEvent(UInt32 *datap=NULL);
    UInt8	peekEvent(UInt32 depth=0);
    
private:
    UInt32	EnqueueIndex;		// ptr to next enqueue element
    UInt32	DequeueIndex;		// ptr to next dequeue element
    UInt32	EnqueueThreshold;	// enqueue threshold
    UInt32	DequeueThreshold;	// dequeue threshold
    UInt16	*Queue;			// actual array of events;
    char	Name[14];
    bool	OverRun;		// if true then enqueues have failed
    
    inline void pushWord(UInt16 data);	
    inline UInt16 pullWord();
};
#endif // _APPLEPCI16X50QUEUE_H