[deliverable/linux.git] / drivers / media / dvb / 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), 0);
**     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(struct dvb_ringbuffer *rbuf, u8 *buf,
				   size_t len, int usermem);


/* 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);


/**
 * 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);

/**
 * 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.
 * <usermem> Set to 1 if <buf> is in userspace.
 * 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, int usermem);

/**
 * 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);

/**
 * 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	/*
	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), 0);
	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.
48c01a9c	72	** Resetting the buffer counts as a read and write operation.
1da177e4 LT	73	** Two or more writers must be locked against each other.
	74	*/
	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 AO	89	/*
	90	** Reset the read and write pointers to zero and flush the buffer
	91	** This counts as a read and write operation
	92	*/
	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
	104	/* peek at byte <offs> in the buffer */
	105	#define DVB_RINGBUFFER_PEEK(rbuf,offs) \
	106	(rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]
	107
	108	/* advance read ptr by <num> bytes */
	109	#define DVB_RINGBUFFER_SKIP(rbuf,num) \
	110	(rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size
	111
	112	/*
	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	*/
	117	extern ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer rbuf, u8 buf,
50c25fff	118	size_t len, int usermem);
1da177e4 LT	119
	120
	121	/* write routines & macros */
	122	/* ----------------------- */
	123	/* write single byte to ring buffer */
	124	#define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \
	125	{ (rbuf)->data[(rbuf)->pwrite]=(byte); \
	126	(rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
	127	/*
	128	** write <len> bytes to ring buffer
	129	** <usermem> specifies whether <buf> resides in user space
	130	** returns number of bytes transferred or -EFAULT
	131	*/
	132	extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer rbuf, const u8 buf,
50c25fff	133	size_t len);
1da177e4 LT	134
	135
	136	/**
	137	* Write a packet into the ringbuffer.
	138	*
	139	* <rbuf> Ringbuffer to write to.
	140	* <buf> Buffer to write.
	141	* <len> Length of buffer (currently limited to 65535 bytes max).
	142	* returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
	143	*/
	144	extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer rbuf, u8 buf,
50c25fff	145	size_t len);
1da177e4 LT	146
	147	/**
	148	* Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this
	149	* does NOT update the read pointer in the ringbuffer. You must use
	150	* dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required.
	151	*
	152	* <rbuf> Ringbuffer concerned.
	153	* <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
	154	* <offset> Offset into packet to read from.
	155	* <buf> Destination buffer for data.
	156	* <len> Size of destination buffer.
	157	* <usermem> Set to 1 if <buf> is in userspace.
	158	* returns Number of bytes read, or -EFAULT.
	159	*/
	160	extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
50c25fff	161	int offset, u8* buf, size_t len, int usermem);
1da177e4 LT	162
	163	/**
	164	* Dispose of a packet in the ring buffer.
	165	*
	166	* <rbuf> Ring buffer concerned.
	167	* <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
	168	*/
	169	extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
	170
	171	/**
	172	* Get the index of the next packet in a ringbuffer.
	173	*
	174	* <rbuf> Ringbuffer concerned.
	175	* <idx> Previous packet index, or -1 to return the first packet index.
	176	* <pktlen> On success, will be updated to contain the length of the packet in bytes.
	177	* returns Packet index (if >=0), or -1 if no packets available.
	178	*/
	179	extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer rbuf, size_t idx, size_t pktlen);
	180
	181
	182	#endif /* _DVB_RINGBUFFER_H_ */