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 * 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 * Read from a packet in the ringbuffer. Note: unlike dvb_ringbuffer_read(), this
153 * does NOT update the read pointer in the ringbuffer. You must use
154 * dvb_ringbuffer_pkt_dispose() to mark a packet as no longer required.
155 *
156 * <rbuf> Ringbuffer concerned.
157 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
158 * <offset> Offset into packet to read from.
159 * <buf> Destination buffer for data.
160 * <len> Size of destination buffer.
161 * <usermem> Set to 1 if <buf> is in userspace.
162 * returns Number of bytes read, or -EFAULT.
163 */
164extern ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
165				       int offset, u8 __user *buf, size_t len);
166extern ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
167				       int offset, u8 *buf, size_t len);
168
169/**
170 * Dispose of a packet in the ring buffer.
171 *
172 * <rbuf> Ring buffer concerned.
173 * <idx> Packet index as returned by dvb_ringbuffer_pkt_next().
174 */
175extern void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx);
176
177/**
178 * Get the index of the next packet in a ringbuffer.
179 *
180 * <rbuf> Ringbuffer concerned.
181 * <idx> Previous packet index, or -1 to return the first packet index.
182 * <pktlen> On success, will be updated to contain the length of the packet in bytes.
183 * returns Packet index (if >=0), or -1 if no packets available.
184 */
185extern ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen);
186
187
188#endif /* _DVB_RINGBUFFER_H_ */
189