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 {
34 u8 *data;
35 ssize_t size;
36 ssize_t pread;
37 ssize_t pwrite;
38
39 wait_queue_head_t queue;
40 spinlock_t lock;
41 };
42
43 #define DVB_RINGBUFFER_PKTHDRSIZE 3
44
45
46 /*
47 ** Notes:
48 ** ------
49 ** (1) For performance reasons read and write routines don't check buffer sizes
50 ** and/or number of bytes free/available. This has to be done before these
51 ** routines are called. For example:
52 **
53 ** *** write <buflen> bytes ***
54 ** free = dvb_ringbuffer_free(rbuf);
55 ** if (free >= buflen)
56 ** count = dvb_ringbuffer_write(rbuf, buffer, buflen);
57 ** else
58 ** ...
59 **
60 ** *** read min. 1000, max. <bufsize> bytes ***
61 ** avail = dvb_ringbuffer_avail(rbuf);
62 ** if (avail >= 1000)
63 ** count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize), 0);
64 ** else
65 ** ...
66 **
67 ** (2) If there is exactly one reader and one writer, there is no need
68 ** to lock read or write operations.
69 ** Two or more readers must be locked against each other.
70 ** Flushing the buffer counts as a read operation.
71 ** Two or more writers must be locked against each other.
72 */
73
74 /* initialize ring buffer, lock and queue */
75 extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len);
76
77 /* test whether buffer is empty */
78 extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
79
80 /* return the number of free bytes in the buffer */
81 extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
82
83 /* return the number of bytes waiting in the buffer */
84 extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
85
86
87 /* read routines & macros */
88 /* ---------------------- */
89 /* flush buffer */
90 extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
91
92 /* flush buffer protected by spinlock and wake-up waiting task(s) */
93 extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
94
95 /* peek at byte <offs> in the buffer */
96 #define DVB_RINGBUFFER_PEEK(rbuf,offs) \
97 (rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]
98
99 /* advance read ptr by <num> bytes */
100 #define DVB_RINGBUFFER_SKIP(rbuf,num) \
101 (rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size
102
103 /*
104 ** read <len> bytes from ring buffer into <buf>
105 ** <usermem> specifies whether <buf> resides in user space
106 ** returns number of bytes transferred or -EFAULT
107 */
108 extern ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf,
109 size_t len, int usermem);
110
111
112 /* write routines & macros */
113 /* ----------------------- */
114 /* write single byte to ring buffer */
115 #define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \
116 { (rbuf)->data[(rbuf)->pwrite]=(byte); \
117 (rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
118 /*
119 ** write <len> bytes to ring buffer
120 ** <usermem> specifies whether <buf> resides in user space
121 ** returns number of bytes transferred or -EFAULT
122 */
123 extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
124 size_t len);
125
126
127 /**
128 * Write a packet into the ringbuffer.
129 *
130 * <rbuf> Ringbuffer to write to.
131 * <buf> Buffer to write.
132 * <len> Length of buffer (currently limited to 65535 bytes max).
133 * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
134 */
135 extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf,
136 size_t len);
137
138 /**
139 * Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this
140 * does NOT update the read pointer in the ringbuffer. You must use
141 * dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required.
142 *
143 * <rbuf> Ringbuffer concerned.
144 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
145 * <offset> Offset into packet to read from.
146 * <buf> Destination buffer for data.
147 * <len> Size of destination buffer.
148 * <usermem> Set to 1 if <buf> is in userspace.
149 * returns Number of bytes read, or -EFAULT.
150 */
151 extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
152 int offset, u8* buf, size_t len, int usermem);
153
154 /**
155 * Dispose of a packet in the ring buffer.
156 *
157 * <rbuf> Ring buffer concerned.
158 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
159 */
160 extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
161
162 /**
163 * Get the index of the next packet in a ringbuffer.
164 *
165 * <rbuf> Ringbuffer concerned.
166 * <idx> Previous packet index, or -1 to return the first packet index.
167 * <pktlen> On success, will be updated to contain the length of the packet in bytes.
168 * returns Packet index (if >=0), or -1 if no packets available.
169 */
170 extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
171
172
173 #endif /* _DVB_RINGBUFFER_H_ */
174
|
This page was automatically generated by the
LXR engine.
|