msgqueue.c
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/*
* linux/drivers/acorn/scsi/msgqueue.c
*
* Copyright (C) 1997-1998 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
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/stddef.h>
#include <linux/init.h>
#include "msgqueue.h"
/*
* Function: struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
* Purpose : Allocate a message queue entry
* Params : msgq - message queue to claim entry for
* Returns : message queue entry or NULL.
*/
static struct msgqueue_entry *mqe_alloc(MsgQueue_t *msgq)
{
struct msgqueue_entry *mq;
if ((mq = msgq->free) != NULL)
msgq->free = mq->next;
return mq;
}
/*
* Function: void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
* Purpose : free a message queue entry
* Params : msgq - message queue to free entry from
* mq - message queue entry to free
*/
static void mqe_free(MsgQueue_t *msgq, struct msgqueue_entry *mq)
{
if (mq) {
mq->next = msgq->free;
msgq->free = mq;
}
}
/*
* Function: void msgqueue_initialise(MsgQueue_t *msgq)
* Purpose : initialise a message queue
* Params : msgq - queue to initialise
*/
void msgqueue_initialise(MsgQueue_t *msgq)
{
int i;
msgq->qe = NULL;
msgq->free = &msgq->entries[0];
for (i = 0; i < NR_MESSAGES; i++)
msgq->entries[i].next = &msgq->entries[i + 1];
msgq->entries[NR_MESSAGES - 1].next = NULL;
}
/*
* Function: void msgqueue_free(MsgQueue_t *msgq)
* Purpose : free a queue
* Params : msgq - queue to free
*/
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
*/
int msgqueue_msglength(MsgQueue_t *msgq)
{
struct msgqueue_entry *mq = msgq->qe;
int length = 0;
for (mq = msgq->qe; mq; mq = mq->next)
length += mq->msg.length;
return length;
}
/*
* Function: struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
* Purpose : return a message
* Params : msgq - queue to obtain message from
* : msgno - message number
* Returns : pointer to message string, or NULL
*/
struct message *msgqueue_getmsg(MsgQueue_t *msgq, int msgno)
{
struct msgqueue_entry *mq;
for (mq = msgq->qe; mq && msgno; mq = mq->next, msgno--);
return mq ? &mq->msg : NULL;
}
/*
* 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
*/
int msgqueue_addmsg(MsgQueue_t *msgq, int length, ...)
{
struct msgqueue_entry *mq = mqe_alloc(msgq);
va_list ap;
if (mq) {
struct msgqueue_entry **mqp;
int i;
va_start(ap, length);
for (i = 0; i < length; i++)
mq->msg.msg[i] = va_arg(ap, unsigned int);
va_end(ap);
mq->msg.length = length;
mq->msg.fifo = 0;
mq->next = NULL;
mqp = &msgq->qe;
while (*mqp)
mqp = &(*mqp)->next;
*mqp = mq;
}
return mq != NULL;
}
/*
* Function: void msgqueue_flush(MsgQueue_t *msgq)
* Purpose : flush all messages from message queue
* Params : msgq - queue to flush
*/
void msgqueue_flush(MsgQueue_t *msgq)
{
struct msgqueue_entry *mq, *mqnext;
for (mq = msgq->qe; mq; mq = mqnext) {
mqnext = mq->next;
mqe_free(msgq, mq);
}
msgq->qe = NULL;
}
EXPORT_SYMBOL(msgqueue_initialise);
EXPORT_SYMBOL(msgqueue_free);
EXPORT_SYMBOL(msgqueue_msglength);
EXPORT_SYMBOL(msgqueue_getmsg);
EXPORT_SYMBOL(msgqueue_addmsg);
EXPORT_SYMBOL(msgqueue_flush);
MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("SCSI message queue handling");
MODULE_LICENSE("GPL");