Release 4.11 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.
*/
#ifndef _DVB_RINGBUFFER_H_
#define _DVB_RINGBUFFER_H_
#include <linux/spinlock.h>
#include <linux/wait.h>
/**
* struct dvb_ringbuffer - Describes a ring buffer used at DVB framework
*
* @data: Area were the ringbuffer data is written
* @size: size of the ringbuffer
* @pread: next position to read
* @pwrite: next position to write
* @error: used by ringbuffer clients to indicate that an error happened.
* @queue: Wait queue used by ringbuffer clients to indicate when buffer
* was filled
* @lock: Spinlock used to protect the ringbuffer
*/
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
/**
* dvb_ringbuffer_init - initialize ring buffer, lock and queue
*
* @rbuf: pointer to struct dvb_ringbuffer
* @data: pointer to the buffer where the data will be stored
* @len: bytes from ring buffer into @buf
*/
extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data,
size_t len);
/**
* dvb_ringbuffer_empty - test whether buffer is empty
*
* @rbuf: pointer to struct dvb_ringbuffer
*/
extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
/**
* dvb_ringbuffer_free - returns the number of free bytes in the buffer
*
* @rbuf: pointer to struct dvb_ringbuffer
*
* Return: number of free bytes in the buffer
*/
extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
/**
* dvb_ringbuffer_avail - returns the number of bytes waiting in the buffer
*
* @rbuf: pointer to struct dvb_ringbuffer
*
* Return: number of bytes waiting in the buffer
*/
extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
/**
* dvb_ringbuffer_reset - resets the ringbuffer to initial state
*
* @rbuf: pointer to struct dvb_ringbuffer
*
* Resets 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
*/
/**
* dvb_ringbuffer_flush - flush buffer
*
* @rbuf: pointer to struct dvb_ringbuffer
*/
extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
/**
* dvb_ringbuffer_flush_spinlock_wakeup- flush buffer protected by spinlock
* and wake-up waiting task(s)
*
* @rbuf: pointer to struct dvb_ringbuffer
*/
extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
/**
* DVB_RINGBUFFER_PEEK - peek at byte @offs in the buffer
*
* @rbuf: pointer to struct dvb_ringbuffer
* @offs: offset inside the ringbuffer
*/
#define DVB_RINGBUFFER_PEEK(rbuf, offs) \
((rbuf)->data[((rbuf)->pread + (offs)) % (rbuf)->size])
/**
* DVB_RINGBUFFER_SKIP - advance read ptr by @num bytes
*
* @rbuf: pointer to struct dvb_ringbuffer
* @num: number of bytes to advance
*/
#define DVB_RINGBUFFER_SKIP(rbuf, num) {\
(rbuf)->pread = ((rbuf)->pread + (num)) % (rbuf)->size;\
}
/**
* dvb_ringbuffer_read_user - Reads a buffer into a user pointer
*
* @rbuf: pointer to struct dvb_ringbuffer
* @buf: pointer to the buffer where the data will be stored
* @len: bytes from ring buffer into @buf
*
* This variant assumes that the buffer is a memory at the userspace. So,
* it will internally call copy_to_user().
*
* Return: number of bytes transferred or -EFAULT
*/
extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf,
u8 __user *buf, size_t len);
/**
* dvb_ringbuffer_read - Reads a buffer into a pointer
*
* @rbuf: pointer to struct dvb_ringbuffer
* @buf: pointer to the buffer where the data will be stored
* @len: bytes from ring buffer into @buf
*
* This variant assumes that the buffer is a memory at the Kernel space
*
* Return: number of bytes transferred or -EFAULT
*/
extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf,
u8 *buf, size_t len);
/*
* write routines & macros
*/
/**
* DVB_RINGBUFFER_WRITE_BYTE - write single byte to ring buffer
*
* @rbuf: pointer to struct dvb_ringbuffer
* @byte: byte to write
*/
#define DVB_RINGBUFFER_WRITE_BYTE(rbuf, byte) \
{ (rbuf)->data[(rbuf)->pwrite] = (byte); \
(rbuf)->pwrite = ((rbuf)->pwrite + 1) % (rbuf)->size; }
/**
* dvb_ringbuffer_write - Writes a buffer into the ringbuffer
*
* @rbuf: pointer to struct dvb_ringbuffer
* @buf: pointer to the buffer where the data will be read
* @len: bytes from ring buffer into @buf
*
* This variant assumes that the buffer is a memory at the Kernel space
*
* return: number of bytes transferred or -EFAULT
*/
extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
size_t len);
/**
* dvb_ringbuffer_write_user - Writes a buffer received via a user pointer
*
* @rbuf: pointer to struct dvb_ringbuffer
* @buf: pointer to the buffer where the data will be read
* @len: bytes from ring buffer into @buf
*
* This variant assumes that the buffer is a memory at the userspace. So,
* it will internally call copy_from_user().
*
* Return: number of bytes transferred or -EFAULT
*/
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).
*
* Return: 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.
*
* @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.
*
* Return: Number of bytes read, or -EFAULT.
*
* .. 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.
*/
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.
*
* Return: 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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