[linux-2.6-block.git] / 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.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef _DVB_RINGBUFFER_H_
#define _DVB_RINGBUFFER_H_

#include <linux/spinlock.h>
#include <linux/wait.h>

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


/*
 * Notes:
 * ------
 * (1) For performance reasons read and write routines don't check buffer sizes
 *     and/or number of bytes free/available. This has to be done before these
 *     routines are called. For example:
 *
 *     *** write @buflen: bytes ***
 *     free = dvb_ringbuffer_free(rbuf);
 *     if (free >= buflen)
 *         count = dvb_ringbuffer_write(rbuf, buffer, buflen);
 *     else
 *         ...
 *
 *     *** read min. 1000, max. @bufsize: bytes ***
 *     avail = dvb_ringbuffer_avail(rbuf);
 *     if (avail >= 1000)
 *         count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize));
 *     else
 *         ...
 *
 * (2) If there is exactly one reader and one writer, there is no need
 *     to lock read or write operations.
 *     Two or more readers must be locked against each other.
 *     Flushing the buffer counts as a read operation.
 *     Resetting the buffer counts as a read and write operation.
 *     Two or more writers must be locked against each other.
 */

/* initialize ring buffer, lock and queue */
extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len);

/* test whether buffer is empty */
extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);

/* return the number of free bytes in the buffer */
extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);

/* return the number of bytes waiting in the buffer */
extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);


/*
 * Reset 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 */
/* ---------------------- */
/* flush buffer */
extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);

/* flush buffer protected by spinlock and wake-up waiting task(s) */
extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);

/* peek at byte @offs: in the buffer */
#define DVB_RINGBUFFER_PEEK(rbuf,offs)	\
			(rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]

/* advance read ptr by @num: bytes */
#define DVB_RINGBUFFER_SKIP(rbuf,num)	\
			(rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size

/*
 * read @len: bytes from ring buffer into @buf:
 * @usermem: specifies whether @buf: resides in user space
 * returns number of bytes transferred or -EFAULT
 */
extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf,
				   u8 __user *buf, size_t len);
extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf,
				   u8 *buf, size_t len);


/* write routines & macros */
/* ----------------------- */
/* write single byte to ring buffer */
#define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte)	\
			{ (rbuf)->data[(rbuf)->pwrite]=(byte); \
			(rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
/*
 * write @len: bytes to ring buffer
 * @usermem: specifies whether @buf: resides in user space
 * returns number of bytes transferred or -EFAULT
*/
extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
				    size_t len);
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).
 * returns 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.
 * 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.
 *
 * @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.
 *
 * returns Number of bytes read, or -EFAULT.
 */
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.
 *
 * returns 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_ */
Commit	Line	Data
1da177e4 LT	1	/*
	2	*
	3	* dvb_ringbuffer.h: ring buffer implementation for the dvb driver
	4	*
	5	* Copyright (C) 2003 Oliver Endriss
	6	* Copyright (C) 2004 Andrew de Quincey
	7	*
	8	* based on code originally found in av7110.c & dvb_ci.c:
	9	* Copyright (C) 1999-2003 Ralph Metzler & Marcus Metzler
	10	* for convergence integrated media GmbH
	11	*
	12	* This program is free software; you can redistribute it and/or
	13	* modify it under the terms of the GNU Lesser General Public License
	14	* as published by the Free Software Foundation; either version 2.1
	15	* of the License, or (at your option) any later version.
	16	*
	17	* This program is distributed in the hope that it will be useful,
	18	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	20	* GNU Lesser General Public License for more details.
	21	*
	22	* You should have received a copy of the GNU Lesser General Public License
	23	* along with this program; if not, write to the Free Software
	24	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	25	*/
	26
	27	#ifndef _DVB_RINGBUFFER_H_
	28	#define _DVB_RINGBUFFER_H_
	29
	30	#include <linux/spinlock.h>
	31	#include <linux/wait.h>
	32
	33	struct dvb_ringbuffer {
afd1a0c9 MCC	34	u8 *data;
	35	ssize_t size;
	36	ssize_t pread;
	37	ssize_t pwrite;
9d9d6bae	38	int error;
1da177e4	39
afd1a0c9 MCC	40	wait_queue_head_t queue;
afd1a0c9 MCC	41	spinlock_t lock;
1da177e4 LT	42	};
	43
	44	#define DVB_RINGBUFFER_PKTHDRSIZE 3
	45
	46
	47	/*
2a86e373 MCC	48	* Notes:
	49	* ------
	50	* (1) For performance reasons read and write routines don't check buffer sizes
	51	* and/or number of bytes free/available. This has to be done before these
	52	* routines are called. For example:
	53	*
	54	* * write @buflen: bytes *
	55	* free = dvb_ringbuffer_free(rbuf);
	56	* if (free >= buflen)
	57	* count = dvb_ringbuffer_write(rbuf, buffer, buflen);
	58	* else
	59	* ...
	60	*
	61	* * read min. 1000, max. @bufsize: bytes *
	62	* avail = dvb_ringbuffer_avail(rbuf);
	63	* if (avail >= 1000)
	64	* count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize));
	65	* else
	66	* ...
	67	*
	68	* (2) If there is exactly one reader and one writer, there is no need
	69	* to lock read or write operations.
	70	* Two or more readers must be locked against each other.
	71	* Flushing the buffer counts as a read operation.
	72	* Resetting the buffer counts as a read and write operation.
	73	* Two or more writers must be locked against each other.
	74	*/
1da177e4 LT	75
	76	/* initialize ring buffer, lock and queue */
	77	extern void dvb_ringbuffer_init(struct dvb_ringbuffer rbuf, void data, size_t len);
	78
	79	/* test whether buffer is empty */
	80	extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
	81
	82	/* return the number of free bytes in the buffer */
	83	extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
	84
	85	/* return the number of bytes waiting in the buffer */
	86	extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
	87
	88
48c01a9c	89	/*
2a86e373 MCC	90	* Reset the read and write pointers to zero and flush the buffer
	91	* This counts as a read and write operation
	92	*/
48c01a9c AO	93	extern void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf);
	94
	95
1da177e4 LT	96	/* read routines & macros */
	97	/* ---------------------- */
	98	/* flush buffer */
	99	extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
	100
	101	/* flush buffer protected by spinlock and wake-up waiting task(s) */
	102	extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
	103
2a86e373	104	/* peek at byte @offs: in the buffer */
1da177e4 LT	105	#define DVB_RINGBUFFER_PEEK(rbuf,offs) \
	106	(rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]
	107
2a86e373	108	/* advance read ptr by @num: bytes */
1da177e4 LT	109	#define DVB_RINGBUFFER_SKIP(rbuf,num) \
	110	(rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size
	111
	112	/*
2a86e373 MCC	113	* read @len: bytes from ring buffer into @buf:
	114	* @usermem: specifies whether @buf: resides in user space
	115	* returns number of bytes transferred or -EFAULT
	116	*/
b0ba0e3a AV	117	extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf,
	118	u8 __user *buf, size_t len);
	119	extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf,
	120	u8 *buf, size_t len);
1da177e4 LT	121
	122
	123	/* write routines & macros */
	124	/* ----------------------- */
	125	/* write single byte to ring buffer */
	126	#define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \
	127	{ (rbuf)->data[(rbuf)->pwrite]=(byte); \
	128	(rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
	129	/*
2a86e373 MCC	130	* write @len: bytes to ring buffer
	131	* @usermem: specifies whether @buf: resides in user space
	132	* returns number of bytes transferred or -EFAULT
1da177e4 LT	133	*/
1da177e4 LT	134	extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer rbuf, const u8 buf,
50c25fff	135	size_t len);
04da2dae MCC	136	extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
04da2dae MCC	137	const u8 __user *buf, size_t len);
1da177e4 LT	138
	139
	140	/**
2a86e373	141	* dvb_ringbuffer_pkt_write - Write a packet into the ringbuffer.
1da177e4	142	*
2a86e373 MCC	143	* @rbuf: Ringbuffer to write to.
	144	* @buf: Buffer to write.
	145	* @len: Length of buffer (currently limited to 65535 bytes max).
1da177e4 LT	146	* returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
	147	*/
	148	extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer rbuf, u8 buf,
50c25fff	149	size_t len);
1da177e4 LT	150
1da177e4 LT	151	/**
2a86e373 MCC	152	* dvb_ringbuffer_pkt_read_user - Read from a packet in the ringbuffer.
	153	* Note: unlike dvb_ringbuffer_read(), this does NOT update the read pointer
	154	* in the ringbuffer. You must use dvb_ringbuffer_pkt_dispose() to mark a
	155	* packet as no longer required.
	156	*
	157	* @rbuf: Ringbuffer concerned.
	158	* @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
	159	* @offset: Offset into packet to read from.
	160	* @buf: Destination buffer for data.
	161	* @len: Size of destination buffer.
	162	*
1da177e4 LT	163	* returns Number of bytes read, or -EFAULT.
1da177e4 LT	164	*/
b0ba0e3a AV	165	extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
b0ba0e3a AV	166	int offset, u8 __user *buf, size_t len);
2a86e373 MCC	167
	168	/**
	169	* dvb_ringbuffer_pkt_read - Read from a packet in the ringbuffer.
	170	* Note: unlike dvb_ringbuffer_read_user(), this DOES update the read pointer
	171	* in the ringbuffer.
	172	*
	173	* @rbuf: Ringbuffer concerned.
	174	* @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
	175	* @offset: Offset into packet to read from.
	176	* @buf: Destination buffer for data.
	177	* @len: Size of destination buffer.
	178	*
	179	* returns Number of bytes read, or -EFAULT.
	180	*/
1da177e4	181	extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
b0ba0e3a	182	int offset, u8 *buf, size_t len);
1da177e4 LT	183
1da177e4 LT	184	/**
2a86e373	185	* dvb_ringbuffer_pkt_dispose - Dispose of a packet in the ring buffer.
1da177e4	186	*
2a86e373 MCC	187	* @rbuf: Ring buffer concerned.
2a86e373 MCC	188	* @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
1da177e4 LT	189	*/
	190	extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
	191
	192	/**
2a86e373	193	* dvb_ringbuffer_pkt_next - Get the index of the next packet in a ringbuffer.
1da177e4	194	*
2a86e373 MCC	195	* @rbuf: Ringbuffer concerned.
	196	* @idx: Previous packet index, or -1 to return the first packet index.
	197	* @pktlen: On success, will be updated to contain the length of the packet in bytes.
1da177e4 LT	198	* returns Packet index (if >=0), or -1 if no packets available.
	199	*/
	200	extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer rbuf, size_t idx, size_t pktlen);
	201
	202
	203	#endif /* _DVB_RINGBUFFER_H_ */