dvb_ringbuffer.c revision 48c01a9c2d245b229f8b709040cb1776b00dc683 
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#include <linux/errno.h>
30#include <linux/kernel.h>
31#include <linux/module.h>
32#include <linux/sched.h>
33#include <linux/string.h>
34#include <asm/uaccess.h>
35
36#include "dvb_ringbuffer.h"
37
38#define PKT_READY 0
39#define PKT_DISPOSED 1
40
41
42void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
43{
44	rbuf->pread=rbuf->pwrite=0;
45	rbuf->data=data;
46	rbuf->size=len;
47	rbuf->error=0;
48
49	init_waitqueue_head(&rbuf->queue);
50
51	spin_lock_init(&(rbuf->lock));
52}
53
54
55
56int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
57{
58	return (rbuf->pread==rbuf->pwrite);
59}
60
61
62
63ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
64{
65	ssize_t free;
66
67	free = rbuf->pread - rbuf->pwrite;
68	if (free <= 0)
69		free += rbuf->size;
70	return free-1;
71}
72
73
74
75ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
76{
77	ssize_t avail;
78
79	avail = rbuf->pwrite - rbuf->pread;
80	if (avail < 0)
81		avail += rbuf->size;
82	return avail;
83}
84
85
86
87void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
88{
89	rbuf->pread = rbuf->pwrite;
90	rbuf->error = 0;
91}
92
93void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf)
94{
95	rbuf->pread = rbuf->pwrite = 0;
96	rbuf->error = 0;
97}
98
99void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
100{
101	unsigned long flags;
102
103	spin_lock_irqsave(&rbuf->lock, flags);
104	dvb_ringbuffer_flush(rbuf);
105	spin_unlock_irqrestore(&rbuf->lock, flags);
106
107	wake_up(&rbuf->queue);
108}
109
110
111
112ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
113{
114	size_t todo = len;
115	size_t split;
116
117	split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
118	if (split > 0) {
119		if (!usermem)
120			memcpy(buf, rbuf->data+rbuf->pread, split);
121		else
122			if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
123				return -EFAULT;
124		buf += split;
125		todo -= split;
126		rbuf->pread = 0;
127	}
128	if (!usermem)
129		memcpy(buf, rbuf->data+rbuf->pread, todo);
130	else
131		if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
132			return -EFAULT;
133
134	rbuf->pread = (rbuf->pread + todo) % rbuf->size;
135
136	return len;
137}
138
139
140
141ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
142{
143	size_t todo = len;
144	size_t split;
145
146	split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
147
148	if (split > 0) {
149		memcpy(rbuf->data+rbuf->pwrite, buf, split);
150		buf += split;
151		todo -= split;
152		rbuf->pwrite = 0;
153	}
154	memcpy(rbuf->data+rbuf->pwrite, buf, todo);
155	rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
156
157	return len;
158}
159
160ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
161{
162	int status;
163	ssize_t oldpwrite = rbuf->pwrite;
164
165	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
166	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
167	DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
168	status = dvb_ringbuffer_write(rbuf, buf, len);
169
170	if (status < 0) rbuf->pwrite = oldpwrite;
171	return status;
172}
173
174ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
175				int offset, u8* buf, size_t len, int usermem)
176{
177	size_t todo;
178	size_t split;
179	size_t pktlen;
180
181	pktlen = rbuf->data[idx] << 8;
182	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
183	if (offset > pktlen) return -EINVAL;
184	if ((offset + len) > pktlen) len = pktlen - offset;
185
186	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
187	todo = len;
188	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
189	if (split > 0) {
190		if (!usermem)
191			memcpy(buf, rbuf->data+idx, split);
192		else
193			if (copy_to_user(buf, rbuf->data+idx, split))
194				return -EFAULT;
195		buf += split;
196		todo -= split;
197		idx = 0;
198	}
199	if (!usermem)
200		memcpy(buf, rbuf->data+idx, todo);
201	else
202		if (copy_to_user(buf, rbuf->data+idx, todo))
203			return -EFAULT;
204
205	return len;
206}
207
208void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
209{
210	size_t pktlen;
211
212	rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
213
214	// clean up disposed packets
215	while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
216		if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
217			pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
218			pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
219			DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
220		} else {
221			// first packet is not disposed, so we stop cleaning now
222			break;
223		}
224	}
225}
226
227ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
228{
229	int consumed;
230	int curpktlen;
231	int curpktstatus;
232
233	if (idx == -1) {
234	       idx = rbuf->pread;
235	} else {
236		curpktlen = rbuf->data[idx] << 8;
237		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
238		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
239	}
240
241	consumed = (idx - rbuf->pread) % rbuf->size;
242
243	while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
244
245		curpktlen = rbuf->data[idx] << 8;
246		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
247		curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
248
249		if (curpktstatus == PKT_READY) {
250			*pktlen = curpktlen;
251			return idx;
252		}
253
254		consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
255		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
256	}
257
258	// no packets available
259	return -1;
260}
261
262
263
264EXPORT_SYMBOL(dvb_ringbuffer_init);
265EXPORT_SYMBOL(dvb_ringbuffer_empty);
266EXPORT_SYMBOL(dvb_ringbuffer_free);
267EXPORT_SYMBOL(dvb_ringbuffer_avail);
268EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
269EXPORT_SYMBOL(dvb_ringbuffer_read);
270EXPORT_SYMBOL(dvb_ringbuffer_write);
271