281 lines
8.3 KiB
C
281 lines
8.3 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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#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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/**
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* struct dvb_ringbuffer - Describes a ring buffer used at DVB framework
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*
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* @data: Area were the ringbuffer data is written
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* @size: size of the ringbuffer
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* @pread: next position to read
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* @pwrite: next position to write
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* @error: used by ringbuffer clients to indicate that an error happened.
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* @queue: Wait queue used by ringbuffer clients to indicate when buffer
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* was filled
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* @lock: Spinlock used to protect the ringbuffer
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*/
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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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* dvb_ringbuffer_init - initialize ring buffer, lock and queue
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @data: pointer to the buffer where the data will be stored
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* @len: bytes from ring buffer into @buf
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*/
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extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data,
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size_t len);
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/**
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* dvb_ringbuffer_empty - test whether buffer is empty
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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*/
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extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
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/**
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* dvb_ringbuffer_free - returns the number of free bytes in the buffer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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*
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* Return: number of free bytes in the buffer
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*/
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extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
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/**
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* dvb_ringbuffer_avail - returns the number of bytes waiting in the buffer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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*
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* Return: number of bytes waiting in the buffer
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*/
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extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
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/**
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* dvb_ringbuffer_reset - resets the ringbuffer to initial state
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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*
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* Resets the read and write pointers to zero and flush the buffer.
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*
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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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/*
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* read routines & macros
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*/
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/**
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* dvb_ringbuffer_flush - flush buffer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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*/
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extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
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/**
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* dvb_ringbuffer_flush_spinlock_wakeup- flush buffer protected by spinlock
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* and wake-up waiting task(s)
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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*/
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extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
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/**
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* DVB_RINGBUFFER_PEEK - peek at byte @offs in the buffer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @offs: offset inside the ringbuffer
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*/
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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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/**
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* DVB_RINGBUFFER_SKIP - advance read ptr by @num bytes
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @num: number of bytes to advance
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*/
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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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/**
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* dvb_ringbuffer_read_user - Reads a buffer into a user pointer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @buf: pointer to the buffer where the data will be stored
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* @len: bytes from ring buffer into @buf
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*
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* This variant assumes that the buffer is a memory at the userspace. So,
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* it will internally call copy_to_user().
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*
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* Return: 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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/**
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* dvb_ringbuffer_read - Reads a buffer into a pointer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @buf: pointer to the buffer where the data will be stored
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* @len: bytes from ring buffer into @buf
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*
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* This variant assumes that the buffer is a memory at the Kernel space
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*
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* Return: number of bytes transferred or -EFAULT
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*/
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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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/*
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* write routines & macros
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*/
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/**
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* DVB_RINGBUFFER_WRITE_BYTE - write single byte to ring buffer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @byte: byte to write
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*/
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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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* dvb_ringbuffer_write - Writes a buffer into the ringbuffer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @buf: pointer to the buffer where the data will be read
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* @len: bytes from ring buffer into @buf
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*
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* This variant assumes that the buffer is a memory at the Kernel space
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*
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* return: 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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/**
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* dvb_ringbuffer_write_user - Writes a buffer received via a user pointer
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*
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* @rbuf: pointer to struct dvb_ringbuffer
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* @buf: pointer to the buffer where the data will be read
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* @len: bytes from ring buffer into @buf
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*
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* This variant assumes that the buffer is a memory at the userspace. So,
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* it will internally call copy_from_user().
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*
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* Return: number of bytes transferred or -EFAULT
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*/
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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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*
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* Return: 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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* Return: 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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* Return: 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
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* 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,
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size_t idx, size_t *pktlen);
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#endif /* _DVB_RINGBUFFER_H_ */
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