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1da177e4 LT |
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 { | |
afd1a0c9 MCC |
34 | u8 *data; |
35 | ssize_t size; | |
36 | ssize_t pread; | |
37 | ssize_t pwrite; | |
9d9d6bae | 38 | int error; |
1da177e4 | 39 | |
afd1a0c9 MCC |
40 | wait_queue_head_t queue; |
41 | spinlock_t lock; | |
1da177e4 LT |
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, | |
50c25fff | 110 | size_t len, int usermem); |
1da177e4 LT |
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, | |
50c25fff | 125 | size_t len); |
1da177e4 LT |
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, | |
50c25fff | 137 | size_t len); |
1da177e4 LT |
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, | |
50c25fff | 153 | int offset, u8* buf, size_t len, int usermem); |
1da177e4 LT |
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_ */ |