dvb_ringbuffer.c revision 4304954eb668ce66fc58f1cab9abb9a9e2584549 
1/*
2 *
3 * dvb_ringbuffer.c: 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
10 *                       & Marcus Metzler 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
28
29#define __KERNEL_SYSCALLS__
30#include <linux/errno.h>
31#include <linux/kernel.h>
32#include <linux/module.h>
33#include <linux/sched.h>
34#include <linux/string.h>
35#include <asm/uaccess.h>
36
37#include "dvb_ringbuffer.h"
38
39#define PKT_READY 0
40#define PKT_DISPOSED 1
41
42
43void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
44{
45	rbuf->pread=rbuf->pwrite=0;
46	rbuf->data=data;
47	rbuf->size=len;
48	rbuf->error=0;
49
50	init_waitqueue_head(&rbuf->queue);
51
52	spin_lock_init(&(rbuf->lock));
53}
54
55
56
57int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
58{
59	return (rbuf->pread==rbuf->pwrite);
60}
61
62
63
64ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
65{
66	ssize_t free;
67
68	free = rbuf->pread - rbuf->pwrite;
69	if (free <= 0)
70		free += rbuf->size;
71	return free-1;
72}
73
74
75
76ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
77{
78	ssize_t avail;
79
80	avail = rbuf->pwrite - rbuf->pread;
81	if (avail < 0)
82		avail += rbuf->size;
83	return avail;
84}
85
86
87
88void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
89{
90	rbuf->pread = rbuf->pwrite;
91	rbuf->error = 0;
92}
93
94
95
96void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
97{
98	unsigned long flags;
99
100	spin_lock_irqsave(&rbuf->lock, flags);
101	dvb_ringbuffer_flush(rbuf);
102	spin_unlock_irqrestore(&rbuf->lock, flags);
103
104	wake_up(&rbuf->queue);
105}
106
107
108
109ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
110{
111	size_t todo = len;
112	size_t split;
113
114	split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
115	if (split > 0) {
116		if (!usermem)
117			memcpy(buf, rbuf->data+rbuf->pread, split);
118		else
119			if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
120				return -EFAULT;
121		buf += split;
122		todo -= split;
123		rbuf->pread = 0;
124	}
125	if (!usermem)
126		memcpy(buf, rbuf->data+rbuf->pread, todo);
127	else
128		if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
129			return -EFAULT;
130
131	rbuf->pread = (rbuf->pread + todo) % rbuf->size;
132
133	return len;
134}
135
136
137
138ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
139{
140	size_t todo = len;
141	size_t split;
142
143	split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
144
145	if (split > 0) {
146		memcpy(rbuf->data+rbuf->pwrite, buf, split);
147		buf += split;
148		todo -= split;
149		rbuf->pwrite = 0;
150	}
151	memcpy(rbuf->data+rbuf->pwrite, buf, todo);
152	rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
153
154	return len;
155}
156
157ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
158{
159	int status;
160	ssize_t oldpwrite = rbuf->pwrite;
161
162	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
163	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
164	DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
165	status = dvb_ringbuffer_write(rbuf, buf, len);
166
167	if (status < 0) rbuf->pwrite = oldpwrite;
168	return status;
169}
170
171ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
172				int offset, u8* buf, size_t len, int usermem)
173{
174	size_t todo;
175	size_t split;
176	size_t pktlen;
177
178	pktlen = rbuf->data[idx] << 8;
179	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
180	if (offset > pktlen) return -EINVAL;
181	if ((offset + len) > pktlen) len = pktlen - offset;
182
183	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
184	todo = len;
185	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
186	if (split > 0) {
187		if (!usermem)
188			memcpy(buf, rbuf->data+idx, split);
189		else
190			if (copy_to_user(buf, rbuf->data+idx, split))
191				return -EFAULT;
192		buf += split;
193		todo -= split;
194		idx = 0;
195	}
196	if (!usermem)
197		memcpy(buf, rbuf->data+idx, todo);
198	else
199		if (copy_to_user(buf, rbuf->data+idx, todo))
200			return -EFAULT;
201
202	return len;
203}
204
205void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
206{
207	size_t pktlen;
208
209	rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
210
211	// clean up disposed packets
212	while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
213		if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
214			pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
215			pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
216			DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
217		} else {
218			// first packet is not disposed, so we stop cleaning now
219			break;
220		}
221	}
222}
223
224ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
225{
226	int consumed;
227	int curpktlen;
228	int curpktstatus;
229
230	if (idx == -1) {
231	       idx = rbuf->pread;
232	} else {
233		curpktlen = rbuf->data[idx] << 8;
234		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
235		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
236	}
237
238	consumed = (idx - rbuf->pread) % rbuf->size;
239
240	while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
241
242		curpktlen = rbuf->data[idx] << 8;
243		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
244		curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
245
246		if (curpktstatus == PKT_READY) {
247			*pktlen = curpktlen;
248			return idx;
249		}
250
251		consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
252		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
253	}
254
255	// no packets available
256	return -1;
257}
258
259
260
261EXPORT_SYMBOL(dvb_ringbuffer_init);
262EXPORT_SYMBOL(dvb_ringbuffer_empty);
263EXPORT_SYMBOL(dvb_ringbuffer_free);
264EXPORT_SYMBOL(dvb_ringbuffer_avail);
265EXPORT_SYMBOL(dvb_ringbuffer_flush);
266EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
267EXPORT_SYMBOL(dvb_ringbuffer_read);
268EXPORT_SYMBOL(dvb_ringbuffer_write);
269EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
270EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
271EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
272EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);
273