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/*
* linux/drivers/acorn/scsi/msgqueue.h
*
* Copyright (C) 1997 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* message queue handling
*/
#ifndef MSGQUEUE_H
#define MSGQUEUE_H
struct message {
char msg[8];
int length;
int fifo;
};
struct msgqueue_entry {
struct message msg;
struct msgqueue_entry *next;
};
#define NR_MESSAGES 4
typedef struct {
struct msgqueue_entry *qe;
struct msgqueue_entry *free;
struct msgqueue_entry entries[NR_MESSAGES];
} MsgQueue_t;
/*
* Function: void msgqueue_initialise(MsgQueue_t *msgq)
* Purpose : initialise a message queue
* Params : msgq - queue to initialise
*/
extern void msgqueue_initialise(MsgQueue_t *msgq);
/*
* Function: void msgqueue_free(MsgQueue_t *msgq)
* Purpose : free a queue
* Params : msgq - queue to free
*/
extern void msgqueue_free(MsgQueue_t *msgq);
/*
* Function: int msgqueue_msglength(MsgQueue_t *msgq)
* Purpose : calculate the total length of all messages on the message queue
* Params : msgq - queue to examine
* Returns : number of bytes of messages in queue
*/
extern int msgqueue_msglength(MsgQueue_t *msgq);
/*
* Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
* Purpose : return a message & its length
* Params : msgq - queue to obtain message from
* : msgno - message number
* Returns : pointer to message string, or NULL
*/
extern struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno);
/*
* Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
* Purpose : add a message onto a message queue
* Params : msgq - queue to add message on
* length - length of message
* ... - message bytes
* Returns : != 0 if successful
*/
extern int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...);
/*
* Function: void msgqueue_flush(MsgQueue_t *msgq)
* Purpose : flush all messages from message queue
* Params : msgq - queue to flush
*/
extern void msgqueue_flush(MsgQueue_t *msgq);
#endif
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