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| -rw-r--r-- | include/media/dvb_ringbuffer.h | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/include/media/dvb_ringbuffer.h b/include/media/dvb_ringbuffer.h new file mode 100644 index 000000000..8ed6bcc3a --- /dev/null +++ b/include/media/dvb_ringbuffer.h @@ -0,0 +1,280 @@ +/* + * + * 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_ */ |