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 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), 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.
72 ** Two or more writers must be locked against each other.
73 */
74
75 /* initialize ring buffer, lock and queue */
76 extern void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len);
77
78 /* test whether buffer is empty */
79 extern int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf);
80
81 /* return the number of free bytes in the buffer */
82 extern ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf);
83
84 /* return the number of bytes waiting in the buffer */
85 extern ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf);
86
87
88 /* read routines & macros */
89 /* ---------------------- */
90 /* flush buffer */
91 extern void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf);
92
93 /* flush buffer protected by spinlock and wake-up waiting task(s) */
94 extern void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf);
95
96 /* peek at byte <offs> in the buffer */
97 #define DVB_RINGBUFFER_PEEK(rbuf,offs) \
98 (rbuf)->data[((rbuf)->pread+(offs))%(rbuf)->size]
99
100 /* advance read ptr by <num> bytes */
101 #define DVB_RINGBUFFER_SKIP(rbuf,num) \
102 (rbuf)->pread=((rbuf)->pread+(num))%(rbuf)->size
103
104 /*
105 ** read <len> bytes from ring buffer into <buf>
106 ** <usermem> specifies whether <buf> resides in user space
107 ** returns number of bytes transferred or -EFAULT
108 */
109 extern ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf,
110 size_t len, int usermem);
111
112
113 /* write routines & macros */
114 /* ----------------------- */
115 /* write single byte to ring buffer */
116 #define DVB_RINGBUFFER_WRITE_BYTE(rbuf,byte) \
117 { (rbuf)->data[(rbuf)->pwrite]=(byte); \
118 (rbuf)->pwrite=((rbuf)->pwrite+1)%(rbuf)->size; }
119 /*
120 ** write <len> bytes to ring buffer
121 ** <usermem> specifies whether <buf> resides in user space
122 ** returns number of bytes transferred or -EFAULT
123 */
124 extern ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf,
125 size_t len);
126
127
128 /**
129 * Write a packet into the ringbuffer.
130 *
131 * <rbuf> Ringbuffer to write to.
132 * <buf> Buffer to write.
133 * <len> Length of buffer (currently limited to 65535 bytes max).
134 * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
135 */
136 extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf,
137 size_t len);
138
139 /**
140 * Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this
141 * does NOT update the read pointer in the ringbuffer. You must use
142 * dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required.
143 *
144 * <rbuf> Ringbuffer concerned.
145 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
146 * <offset> Offset into packet to read from.
147 * <buf> Destination buffer for data.
148 * <len> Size of destination buffer.
149 * <usermem> Set to 1 if <buf> is in userspace.
150 * returns Number of bytes read, or -EFAULT.
151 */
152 extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
153 int offset, u8* buf, size_t len, int usermem);
154
155 /**
156 * Dispose of a packet in the ring buffer.
157 *
158 * <rbuf> Ring buffer concerned.
159 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
160 */
161 extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
162
163 /**
164 * Get the index of the next packet in a ringbuffer.
165 *
166 * <rbuf> Ringbuffer concerned.
167 * <idx> Previous packet index, or -1 to return the first packet index.
168 * <pktlen> On success, will be updated to contain the length of the packet in bytes.
169 * returns Packet index (if >=0), or -1 if no packets available.
170 */
171 extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
172
173
174 #endif /* _DVB_RINGBUFFER_H_ */
175
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