name : 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, -EINVAL. */ 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_ */