mirror of https://gitee.com/openkylin/linux.git
209 lines
6.9 KiB
C
209 lines
6.9 KiB
C
/*
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*
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* dvb_ringbuffer.h: ring buffer implementation for the dvb driver
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*
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* Copyright (C) 2003 Oliver Endriss
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* Copyright (C) 2004 Andrew de Quincey
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*
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* based on code originally found in av7110.c & dvb_ci.c:
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* Copyright (C) 1999-2003 Ralph Metzler & Marcus Metzler
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* for convergence integrated media GmbH
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation; either version 2.1
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifndef _DVB_RINGBUFFER_H_
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#define _DVB_RINGBUFFER_H_
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#include <linux/spinlock.h>
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#include <linux/wait.h>
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struct dvb_ringbuffer {
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u8 *data;
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ssize_t size;
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ssize_t pread;
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ssize_t pwrite;
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int error;
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wait_queue_head_t queue;
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spinlock_t lock;
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};
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#define DVB_RINGBUFFER_PKTHDRSIZE 3
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/*
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* Notes:
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* ------
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* (1) For performance reasons read and write routines don't check buffer sizes
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* and/or number of bytes free/available. This has to be done before these
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* routines are called. For example:
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*
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* *** write @buflen: bytes ***
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* free = dvb_ringbuffer_free(rbuf);
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* if (free >= buflen)
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* count = dvb_ringbuffer_write(rbuf, buffer, buflen);
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* else
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* ...
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*
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* *** read min. 1000, max. @bufsize: bytes ***
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* avail = dvb_ringbuffer_avail(rbuf);
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* if (avail >= 1000)
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* count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize));
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* else
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* ...
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*
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* (2) If there is exactly one reader and one writer, there is no need
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* to lock read or write operations.
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* Two or more readers must be locked against each other.
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* Flushing the buffer counts as a read operation.
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* Resetting the buffer counts as a read and write operation.
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* Two or more writers must be locked against each other.
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*/
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/* initialize ring buffer, lock and queue */
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extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len);
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/* test whether buffer is empty */
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extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
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/* return the number of free bytes in the buffer */
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extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
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/* return the number of bytes waiting in the buffer */
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extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
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/*
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* Reset the read and write pointers to zero and flush the buffer
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* This counts as a read and write operation
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*/
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extern void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf);
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/* read routines & macros */
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/* ---------------------- */
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/* flush buffer */
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extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
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/* flush buffer protected by spinlock and wake-up waiting task(s) */
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extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
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/* peek at byte @offs: in the buffer */
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#define DVB_RINGBUFFER_PEEK(rbuf,offs) \
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(rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]
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/* advance read ptr by @num: bytes */
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#define DVB_RINGBUFFER_SKIP(rbuf,num) \
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(rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size
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/*
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* read @len: bytes from ring buffer into @buf:
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* @usermem: specifies whether @buf: resides in user space
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* returns number of bytes transferred or -EFAULT
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*/
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extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf,
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u8 __user *buf, size_t len);
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extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf,
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u8 *buf, size_t len);
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/* write routines & macros */
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/* ----------------------- */
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/* write single byte to ring buffer */
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#define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \
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{ (rbuf)->data[(rbuf)->pwrite]=(byte); \
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(rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
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/*
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* write @len: bytes to ring buffer
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* @usermem: specifies whether @buf: resides in user space
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* returns number of bytes transferred or -EFAULT
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*/
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extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
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size_t len);
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extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
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const u8 __user *buf, size_t len);
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/**
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* dvb_ringbuffer_pkt_write - Write a packet into the ringbuffer.
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*
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* @rbuf: Ringbuffer to write to.
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* @buf: Buffer to write.
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* @len: Length of buffer (currently limited to 65535 bytes max).
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* returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
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*/
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extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf,
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size_t len);
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/**
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* dvb_ringbuffer_pkt_read_user - Read from a packet in the ringbuffer.
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*
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* @rbuf: Ringbuffer concerned.
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* @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
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* @offset: Offset into packet to read from.
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* @buf: Destination buffer for data.
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* @len: Size of destination buffer.
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*
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* returns Number of bytes read, or -EFAULT.
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*
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* .. note::
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*
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* unlike dvb_ringbuffer_read(), this does **NOT** update the read pointer
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* in the ringbuffer. You must use dvb_ringbuffer_pkt_dispose() to mark a
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* packet as no longer required.
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*/
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extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf,
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size_t idx,
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int offset, u8 __user *buf,
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size_t len);
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/**
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* dvb_ringbuffer_pkt_read - Read from a packet in the ringbuffer.
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* Note: unlike dvb_ringbuffer_read_user(), this DOES update the read pointer
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* in the ringbuffer.
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*
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* @rbuf: Ringbuffer concerned.
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* @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
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* @offset: Offset into packet to read from.
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* @buf: Destination buffer for data.
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* @len: Size of destination buffer.
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*
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* returns Number of bytes read, or -EFAULT.
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*/
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extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
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int offset, u8 *buf, size_t len);
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/**
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* dvb_ringbuffer_pkt_dispose - Dispose of a packet in the ring buffer.
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*
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* @rbuf: Ring buffer concerned.
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* @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
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*/
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extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
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/**
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* dvb_ringbuffer_pkt_next - Get the index of the next packet in a ringbuffer.
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*
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* @rbuf: Ringbuffer concerned.
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* @idx: Previous packet index, or -1 to return the first packet index.
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* @pktlen: On success, will be updated to contain the length of the packet in bytes.
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* returns Packet index (if >=0), or -1 if no packets available.
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*/
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extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
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#endif /* _DVB_RINGBUFFER_H_ */
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