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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);
136extern ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
137 const u8 __user *buf, size_t len);
138
139
140/**
141 * dvb_ringbuffer_pkt_write - Write a packet into the ringbuffer.
142 *
143 * @rbuf: Ringbuffer to write to.
144 * @buf: Buffer to write.
145 * @len: Length of buffer (currently limited to 65535 bytes max).
146 * returns Number of bytes written, or -EFAULT, -ENOMEM, -EVINAL.
147 */
148extern ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf,
149 size_t len);
150
151/**
152 * dvb_ringbuffer_pkt_read_user - Read from a packet in the ringbuffer.
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 *
160 * returns Number of bytes read, or -EFAULT.
161 *
162 * .. note::
163 *
164 * unlike dvb_ringbuffer_read(), this does **NOT** update the read pointer
165 * in the ringbuffer. You must use dvb_ringbuffer_pkt_dispose() to mark a
166 * packet as no longer required.
167 */
168extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf,
169 size_t idx,
170 int offset, u8 __user *buf,
171 size_t len);
172
173/**
174 * dvb_ringbuffer_pkt_read - Read from a packet in the ringbuffer.
175 * Note: unlike dvb_ringbuffer_read_user(), this DOES update the read pointer
176 * in the ringbuffer.
177 *
178 * @rbuf: Ringbuffer concerned.
179 * @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
180 * @offset: Offset into packet to read from.
181 * @buf: Destination buffer for data.
182 * @len: Size of destination buffer.
183 *
184 * returns Number of bytes read, or -EFAULT.
185 */
186extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
187 int offset, u8 *buf, size_t len);
188
189/**
190 * dvb_ringbuffer_pkt_dispose - Dispose of a packet in the ring buffer.
191 *
192 * @rbuf: Ring buffer concerned.
193 * @idx: Packet index as returned by dvb_ringbuffer_pkt_next().
194 */
195extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
196
197/**
198 * dvb_ringbuffer_pkt_next - Get the index of the next packet in a ringbuffer.
199 *
200 * @rbuf: Ringbuffer concerned.
201 * @idx: Previous packet index, or -1 to return the first packet index.
202 * @pktlen: On success, will be updated to contain the length of the packet in bytes.
203 * returns Packet index (if >=0), or -1 if no packets available.
204 */
205extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
206
207
208#endif /* _DVB_RINGBUFFER_H_ */