summaryrefslogtreecommitdiffstats
path: root/drivers/media/dvb-core/dvb_ringbuffer.h
blob: 8ed6bcc3a56e5ffd1299f19bba1db6cda5627fa5 (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
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
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_ */