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}
92EXPORT_SYMBOL(dvb_ringbuffer_flush);
93
94void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf)
95{
96	rbuf->pread = rbuf->pwrite = 0;
97	rbuf->error = 0;
98}
99
100void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
101{
102	unsigned long flags;
103
104	spin_lock_irqsave(&rbuf->lock, flags);
105	dvb_ringbuffer_flush(rbuf);
106	spin_unlock_irqrestore(&rbuf->lock, flags);
107
108	wake_up(&rbuf->queue);
109}
110
111ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len)
112{
113	size_t todo = len;
114	size_t split;
115
116	split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
117	if (split > 0) {
118		if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
119			return -EFAULT;
120		buf += split;
121		todo -= split;
122		rbuf->pread = 0;
123	}
124	if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
125		return -EFAULT;
126
127	rbuf->pread = (rbuf->pread + todo) % rbuf->size;
128
129	return len;
130}
131
132void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len)
133{
134	size_t todo = len;
135	size_t split;
136
137	split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
138	if (split > 0) {
139		memcpy(buf, rbuf->data+rbuf->pread, split);
140		buf += split;
141		todo -= split;
142		rbuf->pread = 0;
143	}
144	memcpy(buf, rbuf->data+rbuf->pread, todo);
145
146	rbuf->pread = (rbuf->pread + todo) % rbuf->size;
147}
148
149
150ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
151{
152	size_t todo = len;
153	size_t split;
154
155	split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
156
157	if (split > 0) {
158		memcpy(rbuf->data+rbuf->pwrite, buf, split);
159		buf += split;
160		todo -= split;
161		rbuf->pwrite = 0;
162	}
163	memcpy(rbuf->data+rbuf->pwrite, buf, todo);
164	rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
165
166	return len;
167}
168
169ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
170				  const u8 __user *buf, size_t len)
171{
172	int status;
173	size_t todo = len;
174	size_t split;
175
176	split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
177
178	if (split > 0) {
179		status = copy_from_user(rbuf->data+rbuf->pwrite, buf, split);
180		if (status)
181			return len - todo;
182		buf += split;
183		todo -= split;
184		rbuf->pwrite = 0;
185	}
186	status = copy_from_user(rbuf->data+rbuf->pwrite, buf, todo);
187	if (status)
188		return len - todo;
189	rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
190
191	return len;
192}
193
194ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
195{
196	int status;
197	ssize_t oldpwrite = rbuf->pwrite;
198
199	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
200	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
201	DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
202	status = dvb_ringbuffer_write(rbuf, buf, len);
203
204	if (status < 0) rbuf->pwrite = oldpwrite;
205	return status;
206}
207
208ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
209				int offset, u8 __user *buf, size_t len)
210{
211	size_t todo;
212	size_t split;
213	size_t pktlen;
214
215	pktlen = rbuf->data[idx] << 8;
216	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
217	if (offset > pktlen) return -EINVAL;
218	if ((offset + len) > pktlen) len = pktlen - offset;
219
220	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
221	todo = len;
222	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
223	if (split > 0) {
224		if (copy_to_user(buf, rbuf->data+idx, split))
225			return -EFAULT;
226		buf += split;
227		todo -= split;
228		idx = 0;
229	}
230	if (copy_to_user(buf, rbuf->data+idx, todo))
231		return -EFAULT;
232
233	return len;
234}
235
236ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
237				int offset, u8* buf, size_t len)
238{
239	size_t todo;
240	size_t split;
241	size_t pktlen;
242
243	pktlen = rbuf->data[idx] << 8;
244	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
245	if (offset > pktlen) return -EINVAL;
246	if ((offset + len) > pktlen) len = pktlen - offset;
247
248	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
249	todo = len;
250	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
251	if (split > 0) {
252		memcpy(buf, rbuf->data+idx, split);
253		buf += split;
254		todo -= split;
255		idx = 0;
256	}
257	memcpy(buf, rbuf->data+idx, todo);
258	return len;
259}
260
261void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
262{
263	size_t pktlen;
264
265	rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
266
267	// clean up disposed packets
268	while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
269		if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
270			pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
271			pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
272			DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
273		} else {
274			// first packet is not disposed, so we stop cleaning now
275			break;
276		}
277	}
278}
279
280ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
281{
282	int consumed;
283	int curpktlen;
284	int curpktstatus;
285
286	if (idx == -1) {
287	       idx = rbuf->pread;
288	} else {
289		curpktlen = rbuf->data[idx] << 8;
290		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
291		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
292	}
293
294	consumed = (idx - rbuf->pread) % rbuf->size;
295
296	while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
297
298		curpktlen = rbuf->data[idx] << 8;
299		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
300		curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
301
302		if (curpktstatus == PKT_READY) {
303			*pktlen = curpktlen;
304			return idx;
305		}
306
307		consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
308		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
309	}
310
311	// no packets available
312	return -1;
313}
314
315
316
317EXPORT_SYMBOL(dvb_ringbuffer_init);
318EXPORT_SYMBOL(dvb_ringbuffer_empty);
319EXPORT_SYMBOL(dvb_ringbuffer_free);
320EXPORT_SYMBOL(dvb_ringbuffer_avail);
321EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
322EXPORT_SYMBOL(dvb_ringbuffer_read_user);
323EXPORT_SYMBOL(dvb_ringbuffer_read);
324EXPORT_SYMBOL(dvb_ringbuffer_write);
325EXPORT_SYMBOL(dvb_ringbuffer_write_user);
326