2019-06-04 16:11:33 +08:00
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/* SPDX-License-Identifier: GPL-2.0-only */
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2005-04-17 06:20:36 +08:00
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/*
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* linux/drivers/acorn/scsi/msgqueue.h
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*
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* Copyright (C) 1997 Russell King
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*
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* message queue handling
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*/
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#ifndef MSGQUEUE_H
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#define MSGQUEUE_H
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struct message {
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char msg[8];
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int length;
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int fifo;
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};
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struct msgqueue_entry {
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struct message msg;
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struct msgqueue_entry *next;
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};
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#define NR_MESSAGES 4
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typedef struct {
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struct msgqueue_entry *qe;
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struct msgqueue_entry *free;
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struct msgqueue_entry entries[NR_MESSAGES];
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} MsgQueue_t;
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/*
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* Function: void msgqueue_initialise(MsgQueue_t *msgq)
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* Purpose : initialise a message queue
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* Params : msgq - queue to initialise
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*/
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extern void msgqueue_initialise(MsgQueue_t *msgq);
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/*
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* Function: void msgqueue_free(MsgQueue_t *msgq)
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* Purpose : free a queue
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* Params : msgq - queue to free
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*/
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extern void msgqueue_free(MsgQueue_t *msgq);
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/*
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* Function: int msgqueue_msglength(MsgQueue_t *msgq)
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* Purpose : calculate the total length of all messages on the message queue
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* Params : msgq - queue to examine
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* Returns : number of bytes of messages in queue
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*/
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extern int msgqueue_msglength(MsgQueue_t *msgq);
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/*
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* Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
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* Purpose : return a message & its length
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* Params : msgq - queue to obtain message from
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* : msgno - message number
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* Returns : pointer to message string, or NULL
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*/
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extern struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno);
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/*
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* Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
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* Purpose : add a message onto a message queue
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* Params : msgq - queue to add message on
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* length - length of message
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* ... - message bytes
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* Returns : != 0 if successful
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*/
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extern int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...);
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/*
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* Function: void msgqueue_flush(MsgQueue_t *msgq)
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* Purpose : flush all messages from message queue
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* Params : msgq - queue to flush
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*/
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extern void msgqueue_flush(MsgQueue_t *msgq);
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#endif
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