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Diffstat (limited to 'drivers/media/dvb/dvb-core/dvb_ringbuffer.h')
-rw-r--r--drivers/media/dvb/dvb-core/dvb_ringbuffer.h186
1 files changed, 186 insertions, 0 deletions
diff --git a/drivers/media/dvb/dvb-core/dvb_ringbuffer.h b/drivers/media/dvb/dvb-core/dvb_ringbuffer.h
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+++ b/drivers/media/dvb/dvb-core/dvb_ringbuffer.h
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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
33struct dvb_ringbuffer {
34 u8 *data;
35 ssize_t size;
36 ssize_t pread;
37 ssize_t pwrite;
38 int error;
39
40 wait_queue_head_t queue;
41 spinlock_t lock;
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));
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*/
75
76/* initialize ring buffer, lock and queue */
77extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len);
78
79/* test whether buffer is empty */
80extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
81
82/* return the number of free bytes in the buffer */
83extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
84
85/* return the number of bytes waiting in the buffer */
86extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
87
88
89/*
90** Reset the read and write pointers to zero and flush the buffer
91** This counts as a read and write operation
92*/
93extern void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf);
94
95
96/* read routines & macros */
97/* ---------------------- */
98/* flush buffer */
99extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
100
101/* flush buffer protected by spinlock and wake-up waiting task(s) */
102extern 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*/
117extern ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf,
118 u8 __user *buf, size_t len);
119extern void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf,
120 u8 *buf, size_t len);
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/*
130** write <len> bytes to ring buffer
131** <usermem> specifies whether <buf> resides in user space
132** returns number of bytes transferred or -EFAULT
133*/
134extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
135 size_t len);
136
137
138/**
139 * Write a packet into the ringbuffer.
140 *
141 * <rbuf> Ringbuffer to write to.
142 * <buf> Buffer to write.
143 * <len> Length of buffer (currently limited to 65535 bytes max).
144 * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
145 */
146extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf,
147 size_t len);
148
149/**
150 * Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this
151 * does NOT update the read pointer in the ringbuffer. You must use
152 * dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required.
153 *
154 * <rbuf> Ringbuffer concerned.
155 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
156 * <offset> Offset into packet to read from.
157 * <buf> Destination buffer for data.
158 * <len> Size of destination buffer.
159 * <usermem> Set to 1 if <buf> is in userspace.
160 * returns Number of bytes read, or -EFAULT.
161 */
162extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
163 int offset, u8 __user *buf, size_t len);
164extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
165 int offset, u8 *buf, size_t len);
166
167/**
168 * Dispose of a packet in the ring buffer.
169 *
170 * <rbuf> Ring buffer concerned.
171 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
172 */
173extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
174
175/**
176 * Get the index of the next packet in a ringbuffer.
177 *
178 * <rbuf> Ringbuffer concerned.
179 * <idx> Previous packet index, or -1 to return the first packet index.
180 * <pktlen> On success, will be updated to contain the length of the packet in bytes.
181 * returns Packet index (if >=0), or -1 if no packets available.
182 */
183extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
184
185
186#endif /* _DVB_RINGBUFFER_H_ */
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