Release 4.7 drivers/media/dvb-core/dvb_ringbuffer.h
/*
*
* 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;
int error;
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));
* 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.
* Resetting the buffer counts as a read and write 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);
/*
* Reset the read and write pointers to zero and flush the buffer
* This counts as a read and write operation
*/
extern void dvb_ringbuffer_reset(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_user(struct dvb_ringbuffer *rbuf,
u8 __user *buf, size_t len);
extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf,
u8 *buf, size_t len);
/* 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);
extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
const u8 __user *buf, size_t len);
/**
* dvb_ringbuffer_pkt_write - 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);
/**
* dvb_ringbuffer_pkt_read_user - 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.
*
* returns Number of bytes read, or -EFAULT.
*/
extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
int offset, u8 __user *buf, size_t len);
/**
* dvb_ringbuffer_pkt_read - Read from a packet in the ringbuffer.
* Note: unlike dvb_ringbuffer_read_user(), this DOES update the read pointer
* in the ringbuffer.
*
* @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.
*
* 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);
/**
* dvb_ringbuffer_pkt_dispose - 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);
/**
* dvb_ringbuffer_pkt_next - 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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