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/*
*
* dvb_ringbuffer.h: 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.
*/
#ifndef _DVB_RINGBUFFER_H_
#define _DVB_RINGBUFFER_H_
#include <linux/spinlock.h>
#include <linux/wait.h>
struct dvb_ringbuffer {
u8 *data;
ssize_t size;
ssize_t pread;
ssize_t pwrite;
wait_queue_head_t queue;
spinlock_t lock;
};
#define DVB_RINGBUFFER_PKTHDRSIZE 3
/*
** Notes:
** ------
** (1) For performance reasons read and write routines don't check buffer sizes
** and/or number of bytes free/available. This has to be done before these
** routines are called. For example:
**
** *** write <buflen> bytes ***
** free = dvb_ringbuffer_free(rbuf);
** if (free >= buflen)
** count = dvb_ringbuffer_write(rbuf, buffer, buflen);
** else
** ...
**
** *** read min. 1000, max. <bufsize> bytes ***
** avail = dvb_ringbuffer_avail(rbuf);
** if (avail >= 1000)
** count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize), 0);
** else
** ...
**
** (2) If there is exactly one reader and one writer, there is no need
** to lock read or write operations.
** Two or more readers must be locked against each other.
** Flushing the buffer counts as a read operation.
** Two or more writers must be locked against each other.
*/
/* initialize ring buffer, lock and queue */
extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len);
/* test whether buffer is empty */
extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
/* return the number of free bytes in the buffer */
extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
/* return the number of bytes waiting in the buffer */
extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
/* read routines & macros */
/* ---------------------- */
/* flush buffer */
extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
/* flush buffer protected by spinlock and wake-up waiting task(s) */
extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
/* peek at byte <offs> in the buffer */
#define DVB_RINGBUFFER_PEEK(rbuf,offs) \
(rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]
/* advance read ptr by <num> bytes */
#define DVB_RINGBUFFER_SKIP(rbuf,num) \
(rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size
/*
** read <len> bytes from ring buffer into <buf>
** <usermem> specifies whether <buf> resides in user space
** returns number of bytes transferred or -EFAULT
*/
extern ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf,
size_t len, int usermem);
/* write routines & macros */
/* ----------------------- */
/* write single byte to ring buffer */
#define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \
{ (rbuf)->data[(rbuf)->pwrite]=(byte); \
(rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
/*
** write <len> bytes to ring buffer
** <usermem> specifies whether <buf> resides in user space
** returns number of bytes transferred or -EFAULT
*/
extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
size_t len);
/**
* Write a packet into the ringbuffer.
*
* <rbuf> Ringbuffer to write to.
* <buf> Buffer to write.
* <len> Length of buffer (currently limited to 65535 bytes max).
* returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
*/
extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf,
size_t len);
/**
* Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this
* does NOT update the read pointer in the ringbuffer. You must use
* dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required.
*
* <rbuf> Ringbuffer concerned.
* <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
* <offset> Offset into packet to read from.
* <buf> Destination buffer for data.
* <len> Size of destination buffer.
* <usermem> Set to 1 if <buf> is in userspace.
* returns Number of bytes read, or -EFAULT.
*/
extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
int offset, u8* buf, size_t len, int usermem);
/**
* Dispose of a packet in the ring buffer.
*
* <rbuf> Ring buffer concerned.
* <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
*/
extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
/**
* Get the index of the next packet in a ringbuffer.
*
* <rbuf> Ringbuffer concerned.
* <idx> Previous packet index, or -1 to return the first packet index.
* <pktlen> On success, will be updated to contain the length of the packet in bytes.
* returns Packet index (if >=0), or -1 if no packets available.
*/
extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
#endif /* _DVB_RINGBUFFER_H_ */
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