aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/media/dvb-core/dvb_ringbuffer.h
blob: 41f04dae69b618badd91e783a1ad463b6bd0a393 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
/*
 *
 * 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);


/**
 * 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_user(struct dvb_ringbuffer *rbuf, size_t idx,
				       int offset, u8 __user *buf, size_t len);
extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
				       int offset, u8 *buf, size_t len);

/**
 * 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_ */

Privacy Policy