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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 { | |
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_ */ |