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 
42 void 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 
56 int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
57 {
58 	return (rbuf->pread==rbuf->pwrite);
59 }
60 
61 
62 
63 ssize_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 
75 ssize_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 
87 void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
88 {
89 	rbuf->pread = rbuf->pwrite;
90 	rbuf->error = 0;
91 }
92 EXPORT_SYMBOL(dvb_ringbuffer_flush);
93 
94 void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf)
95 {
96 	rbuf->pread = rbuf->pwrite = 0;
97 	rbuf->error = 0;
98 }
99 
100 void 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 
111 ssize_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 
132 void 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 
150 ssize_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 
169 ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
170 {
171 	int status;
172 	ssize_t oldpwrite = rbuf->pwrite;
173 
174 	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
175 	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
176 	DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
177 	status = dvb_ringbuffer_write(rbuf, buf, len);
178 
179 	if (status < 0) rbuf->pwrite = oldpwrite;
180 	return status;
181 }
182 
183 ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
184 				int offset, u8 __user *buf, size_t len)
185 {
186 	size_t todo;
187 	size_t split;
188 	size_t pktlen;
189 
190 	pktlen = rbuf->data[idx] << 8;
191 	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
192 	if (offset > pktlen) return -EINVAL;
193 	if ((offset + len) > pktlen) len = pktlen - offset;
194 
195 	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
196 	todo = len;
197 	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
198 	if (split > 0) {
199 		if (copy_to_user(buf, rbuf->data+idx, split))
200 			return -EFAULT;
201 		buf += split;
202 		todo -= split;
203 		idx = 0;
204 	}
205 	if (copy_to_user(buf, rbuf->data+idx, todo))
206 		return -EFAULT;
207 
208 	return len;
209 }
210 
211 ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
212 				int offset, u8* buf, size_t len)
213 {
214 	size_t todo;
215 	size_t split;
216 	size_t pktlen;
217 
218 	pktlen = rbuf->data[idx] << 8;
219 	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
220 	if (offset > pktlen) return -EINVAL;
221 	if ((offset + len) > pktlen) len = pktlen - offset;
222 
223 	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
224 	todo = len;
225 	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
226 	if (split > 0) {
227 		memcpy(buf, rbuf->data+idx, split);
228 		buf += split;
229 		todo -= split;
230 		idx = 0;
231 	}
232 	memcpy(buf, rbuf->data+idx, todo);
233 	return len;
234 }
235 
236 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
237 {
238 	size_t pktlen;
239 
240 	rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
241 
242 	// clean up disposed packets
243 	while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
244 		if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
245 			pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
246 			pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
247 			DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
248 		} else {
249 			// first packet is not disposed, so we stop cleaning now
250 			break;
251 		}
252 	}
253 }
254 
255 ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
256 {
257 	int consumed;
258 	int curpktlen;
259 	int curpktstatus;
260 
261 	if (idx == -1) {
262 	       idx = rbuf->pread;
263 	} else {
264 		curpktlen = rbuf->data[idx] << 8;
265 		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
266 		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
267 	}
268 
269 	consumed = (idx - rbuf->pread) % rbuf->size;
270 
271 	while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
272 
273 		curpktlen = rbuf->data[idx] << 8;
274 		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
275 		curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
276 
277 		if (curpktstatus == PKT_READY) {
278 			*pktlen = curpktlen;
279 			return idx;
280 		}
281 
282 		consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
283 		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
284 	}
285 
286 	// no packets available
287 	return -1;
288 }
289 
290 
291 
292 EXPORT_SYMBOL(dvb_ringbuffer_init);
293 EXPORT_SYMBOL(dvb_ringbuffer_empty);
294 EXPORT_SYMBOL(dvb_ringbuffer_free);
295 EXPORT_SYMBOL(dvb_ringbuffer_avail);
296 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
297 EXPORT_SYMBOL(dvb_ringbuffer_read_user);
298 EXPORT_SYMBOL(dvb_ringbuffer_read);
299 EXPORT_SYMBOL(dvb_ringbuffer_write);
300