path: root/drivers/media/dvb/dvb-core/dmxdev.c

/*
 * dmxdev.c - DVB demultiplexer device
 *
 * Copyright (C) 2000 Ralph  Metzler <ralph@convergence.de>
 *		  & Marcus Metzler <marcus@convergence.de>
		      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 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/spinlock.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/ioctl.h>
#include <linux/wait.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#include "dmxdev.h"

static int debug;

module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "Turn on/off debugging (default:off).");

#define dprintk	if (debug) printk

static inline void dvb_dmxdev_buffer_init(struct dmxdev_buffer *buffer)
{
	buffer->data=NULL;
	buffer->size=8192;
	buffer->pread=0;
	buffer->pwrite=0;
	buffer->error=0;
	init_waitqueue_head(&buffer->queue);
}

static inline int dvb_dmxdev_buffer_write(struct dmxdev_buffer *buf, const u8 *src, int len)
{
	int split;
	int free;
	int todo;

	if (!len)
		return 0;
	if (!buf->data)
		return 0;

	free=buf->pread-buf->pwrite;
	split=0;
	if (free<=0) {
		free+=buf->size;
		split=buf->size-buf->pwrite;
	}
	if (len>=free) {
		dprintk("dmxdev: buffer overflow\n");
		return -1;
	}
	if (split>=len)
		split=0;
	todo=len;
	if (split) {
		memcpy(buf->data + buf->pwrite, src, split);
		todo-=split;
		buf->pwrite=0;
	}
	memcpy(buf->data + buf->pwrite, src+split, todo);
	buf->pwrite=(buf->pwrite+todo)%buf->size;
	return len;
}

static ssize_t dvb_dmxdev_buffer_read(struct dmxdev_buffer *src,
		int non_blocking, char __user *buf, size_t count, loff_t *ppos)
{
	unsigned long todo=count;
	int split, avail, error;

	if (!src->data)
		return 0;

	if ((error=src->error)) {
		src->pwrite=src->pread;
		src->error=0;
		return error;
	}

	if (non_blocking && (src->pwrite==src->pread))
		return -EWOULDBLOCK;

	while (todo>0) {
		if (non_blocking && (src->pwrite==src->pread))
			return (count-todo) ? (count-todo) : -EWOULDBLOCK;

		if (wait_event_interruptible(src->queue,
					     (src->pread!=src->pwrite) ||
					     (src->error))<0)
			return count-todo;

		if ((error=src->error)) {
			src->pwrite=src->pread;
			src->error=0;
			return error;
		}