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/*

 * msgqueue.h: message queue handling

 *

 * (c) 1997 Russell King

 */

#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