/* Copyright (C) 2006 Ikanos Communications 
 * See IKANOS_PROP_LICENSE.txt for license information. */


//======================================================================
// File Name	:	$RCSfile: apipc.h,v $
// Description	:	Define queue based interface for AP -> host packets
//====================================================================== 

#ifndef _APIPC_H_
#define _APIPC_H_

/* AP ingress and egress ports may need to forward packets (chains of
 * clusters) to the system host CPU.
 *
 * This interface performs those tasks. It has the following features
 *      - supports multiple queues (data prioritization)
 *      - queue indexes seperate from queues (allows indexes to be in
 *        fast memory for lower overheads)
 *
 * When the AP writes to the queue it will update the apNextRead index for the
 * queue, and set the interrupt bit that matches the queue.
 *
 * The host CPU will then clear the interrupt bit and read the entry at
 * hostNextRead, and do a circular increment. This process will continue until 
 * apNextWrite == hostNextRead
 *
 * Note that the maximum capacity of the queue is maxEntries - 1.
 */

/* This structure represents the configuration information for a queue. This
 * will typically be supplied by the host CPU
 */
typedef struct
{
    void                *pQueue;        // Physical address of the queue
    unsigned short      maxEntries;     /* Size of the queue, in entries.
                                         * The size of an entry depends on the
                                         * type of queue.
                                         */
} apQueueSpec_t;

/* The following structure represents the head and tail indexes for the queue.
 * They are constrained to be in the range 0 .. maxEntries - 1 of the queue
 *
 * Typically there will be an array of these to represent all the queues
 */
typedef struct
{
    unsigned short      nextWrite;      // Next index to write
    unsigned short      nextRead;       // Next index to read
} apQueueState_t;

#endif /* _APIPC_H_ */