/*
 *
 * dvb_ringbuffer.c: ring buffer implementation for the dvb driver
 *
 * Copyright (C) 2003 Oliver Endriss
 * Copyright (C) 2004 Andrew de Quincey
 *
 * based on code originally found in av7110.c & dvb_ci.c:
 * Copyright (C) 1999-2003 Ralph  Metzler
 *                       & Marcus Metzler for convergence integrated media GmbH
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */



#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <asm/uaccess.h>

#include "cmmb_ringbuffer.h"


void cmmb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
{
	rbuf->pread=rbuf->pwrite=0;
	rbuf->data=data;
	rbuf->size=len;
	rbuf->error=0;

	init_waitqueue_head(&rbuf->queue);

	spin_lock_init(&(rbuf->lock));
    
}



int cmmb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
{
	return (rbuf->pread==rbuf->pwrite);
}



ssize_t cmmb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
{
	ssize_t free;

	free = rbuf->pread - rbuf->pwrite;
	if (free <= 0)
		free += rbuf->size;
	return free-1;
}



ssize_t cmmb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
{
	ssize_t avail;

	avail = rbuf->pwrite - rbuf->pread;
	if (avail < 0)
		avail += rbuf->size;
	return avail;
}



void cmmb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
{
	rbuf->pread = rbuf->pwrite;
	rbuf->error = 0;
}



void cmmb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
{
	unsigned long flags;

	spin_lock_irqsave(&rbuf->lock, flags);
	cmmb_ringbuffer_flush(rbuf);
	spin_unlock_irqrestore(&rbuf->lock, flags);

	wake_up(&rbuf->queue);
}



ssize_t cmmb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
{
	size_t todo = len;
	size_t split;

	split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
	if (split > 0) {
		if (!usermem)
			memcpy(buf, rbuf->data+rbuf->pread, split);
		else
			if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
				return -EFAULT;
		buf += split;
		todo -= split;
		rbuf->pread = 0;
	}
	if (!usermem)
		memcpy(buf, rbuf->data+rbuf->pread, todo);
	else
		if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
			return -EFAULT;

	rbuf->pread = (rbuf->pread + todo) % rbuf->size;

	return len;
}



ssize_t cmmb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
{
	size_t todo = len;
	size_t split;

	split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;

	if (split > 0) {
		memcpy(rbuf->data+rbuf->pwrite, buf, split);
		buf += split;
		todo -= split;
		rbuf->pwrite = 0;
	}
	memcpy(rbuf->data+rbuf->pwrite, buf, todo);
	rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;

	return len;
}




EXPORT_SYMBOL(cmmb_ringbuffer_init);
EXPORT_SYMBOL(cmmb_ringbuffer_empty);
EXPORT_SYMBOL(cmmb_ringbuffer_free);
EXPORT_SYMBOL(cmmb_ringbuffer_avail);
EXPORT_SYMBOL(cmmb_ringbuffer_flush_spinlock_wakeup);
EXPORT_SYMBOL(cmmb_ringbuffer_read);
EXPORT_SYMBOL(cmmb_ringbuffer_write);