drivers/scsi/arm/msgqueue.h

   1 /*
   2  *  linux/drivers/acorn/scsi/msgqueue.h
   3  *
   4  *  Copyright (C) 1997 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  message queue handling
  11  */
  12 #ifndef MSGQUEUE_H
  13 #define MSGQUEUE_H
  14
  15 struct message {
  16     char msg[8];
  17     int length;
  18     int fifo;
  19 };
  20
  21 struct msgqueue_entry {
  22     struct message msg;
  23     struct msgqueue_entry *next;
  24 };
  25
  26 #define NR_MESSAGES 4
  27
  28 typedef struct {
  29     struct msgqueue_entry *qe;
  30     struct msgqueue_entry *free;
  31     struct msgqueue_entry entries[NR_MESSAGES];
  32 } MsgQueue_t;
  33
  34 /*
  35  * Function: void msgqueue_initialise(MsgQueue_t *msgq)
  36  * Purpose : initialise a message queue
  37  * Params  : msgq - queue to initialise
  38  */
  39 extern void msgqueue_initialise(MsgQueue_t *msgq);
  40
  41 /*
  42  * Function: void msgqueue_free(MsgQueue_t *msgq)
  43  * Purpose : free a queue
  44  * Params  : msgq - queue to free
  45  */
  46 extern void msgqueue_free(MsgQueue_t *msgq);
  47
  48 /*
  49  * Function: int msgqueue_msglength(MsgQueue_t *msgq)
  50  * Purpose : calculate the total length of all messages on the message queue
  51  * Params  : msgq - queue to examine
  52  * Returns : number of bytes of messages in queue
  53  */
  54 extern int msgqueue_msglength(MsgQueue_t *msgq);
  55
  56 /*
  57  * Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
  58  * Purpose : return a message & its length
  59  * Params  : msgq   - queue to obtain message from
  60  *         : msgno  - message number
  61  * Returns : pointer to message string, or NULL
  62  */
  63 extern struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno);
  64
  65 /*
  66  * Function: int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
  67  * Purpose : add a message onto a message queue
  68  * Params  : msgq   - queue to add message on
  69  *           length - length of message
  70  *           ...    - message bytes
  71  * Returns : != 0 if successful
  72  */
  73 extern int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...);
  74
  75 /*
  76  * Function: void msgqueue_flush(MsgQueue_t *msgq)
  77  * Purpose : flush all messages from message queue
  78  * Params  : msgq - queue to flush
  79  */
  80 extern void msgqueue_flush(MsgQueue_t *msgq);
  81
  82 #endif