/*
 * Copyright (C) 1997-2000 SpellCaster Telecommunications Inc.
 * $Id: msgq.h,v 1.1 2004/03/11 03:59:31 bcrl Exp $
 * Released under the GNU Public License. See LICENSE file for details.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <asm/segment.h>
#include <linux/wait.h>
#include <asm/errno.h>

#include "vercomp.h"

struct qMsg {
	struct qMsg *next;
	struct qMsg *prev;
	void *data;
	int len;
};

struct MsgQ {
	struct qMsg *msgQ;
	wait_queue_head_t wait;
};


extern inline void initMsgQ(struct MsgQ *q)
{
	init_waitqueue_head(&q->wait);
}

int queueMsg ( struct MsgQ *q, void *data, int len )
{
	struct qMsg *msg;
	unsigned long flags;

	msg = kmalloc(sizeof(struct qMsg) + len, GFP_ATOMIC);
	if (!msg)
		return -ENOMEM;
	msg->data = msg+1;
	msg->len = len;
	memcpy(msg->data, data, len);

	save_flags(flags);
	cli();
	if (!q->msgQ) {
		msg->next = msg;
		msg->prev = msg;
		q->msgQ = msg;
	} else {
		msg->next = q->msgQ;
		msg->prev = q->msgQ->prev;
		msg->prev->next = msg;
		msg->next->prev = msg;
	}
	restore_flags(flags);
	wake_up_interruptible(&q->wait);
	return 0;
}

struct qMsg *getMsg (struct MsgQ *q)
{
	struct qMsg *msg;

	cli();
	msg = q->msgQ;
	if (msg) {
		if (q->msgQ == q->msgQ->next)
			q->msgQ = NULL;
		else {
			q->msgQ->prev->next = q->msgQ->next;
			q->msgQ->next->prev = q->msgQ->prev;
			q->msgQ = q->msgQ->next;
		}
	}
	sti();
	return msg;
}

struct qMsg *waitMsg(struct MsgQ *q)
{
	DECLARE_WAITQUEUE(wait, current);
	struct qMsg *msg = NULL;

	current->state = TASK_INTERRUPTIBLE;
	add_wait_queue(&q->wait, &wait);
	while (!q->msgQ || !(msg = getMsg(q))) {
		schedule();
		if (signal_pending(current))
			break;
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&q->wait, &wait);

	return msg;
}