Merge git://git.infradead.org/~dedekind/ubi-2.6
[linux-2.6] / drivers / media / dvb / dvb-core / dvb_ringbuffer.c
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
93
94
95 void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
96 {
97         unsigned long flags;
98
99         spin_lock_irqsave(&rbuf->lock, flags);
100         dvb_ringbuffer_flush(rbuf);
101         spin_unlock_irqrestore(&rbuf->lock, flags);
102
103         wake_up(&rbuf->queue);
104 }
105
106
107
108 ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
109 {
110         size_t todo = len;
111         size_t split;
112
113         split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
114         if (split > 0) {
115                 if (!usermem)
116                         memcpy(buf, rbuf->data+rbuf->pread, split);
117                 else
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 (!usermem)
125                 memcpy(buf, rbuf->data+rbuf->pread, todo);
126         else
127                 if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
128                         return -EFAULT;
129
130         rbuf->pread = (rbuf->pread + todo) % rbuf->size;
131
132         return len;
133 }
134
135
136
137 ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
138 {
139         size_t todo = len;
140         size_t split;
141
142         split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
143
144         if (split > 0) {
145                 memcpy(rbuf->data+rbuf->pwrite, buf, split);
146                 buf += split;
147                 todo -= split;
148                 rbuf->pwrite = 0;
149         }
150         memcpy(rbuf->data+rbuf->pwrite, buf, todo);
151         rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
152
153         return len;
154 }
155
156 ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
157 {
158         int status;
159         ssize_t oldpwrite = rbuf->pwrite;
160
161         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
162         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
163         DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
164         status = dvb_ringbuffer_write(rbuf, buf, len);
165
166         if (status < 0) rbuf->pwrite = oldpwrite;
167         return status;
168 }
169
170 ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
171                                 int offset, u8* buf, size_t len, int usermem)
172 {
173         size_t todo;
174         size_t split;
175         size_t pktlen;
176
177         pktlen = rbuf->data[idx] << 8;
178         pktlen |= rbuf->data[(idx + 1) % rbuf->size];
179         if (offset > pktlen) return -EINVAL;
180         if ((offset + len) > pktlen) len = pktlen - offset;
181
182         idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
183         todo = len;
184         split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
185         if (split > 0) {
186                 if (!usermem)
187                         memcpy(buf, rbuf->data+idx, split);
188                 else
189                         if (copy_to_user(buf, rbuf->data+idx, split))
190                                 return -EFAULT;
191                 buf += split;
192                 todo -= split;
193                 idx = 0;
194         }
195         if (!usermem)
196                 memcpy(buf, rbuf->data+idx, todo);
197         else
198                 if (copy_to_user(buf, rbuf->data+idx, todo))
199                         return -EFAULT;
200
201         return len;
202 }
203
204 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
205 {
206         size_t pktlen;
207
208         rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
209
210         // clean up disposed packets
211         while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
212                 if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
213                         pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
214                         pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
215                         DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
216                 } else {
217                         // first packet is not disposed, so we stop cleaning now
218                         break;
219                 }
220         }
221 }
222
223 ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
224 {
225         int consumed;
226         int curpktlen;
227         int curpktstatus;
228
229         if (idx == -1) {
230                idx = rbuf->pread;
231         } else {
232                 curpktlen = rbuf->data[idx] << 8;
233                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
234                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
235         }
236
237         consumed = (idx - rbuf->pread) % rbuf->size;
238
239         while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
240
241                 curpktlen = rbuf->data[idx] << 8;
242                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
243                 curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
244
245                 if (curpktstatus == PKT_READY) {
246                         *pktlen = curpktlen;
247                         return idx;
248                 }
249
250                 consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
251                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
252         }
253
254         // no packets available
255         return -1;
256 }
257
258
259
260 EXPORT_SYMBOL(dvb_ringbuffer_init);
261 EXPORT_SYMBOL(dvb_ringbuffer_empty);
262 EXPORT_SYMBOL(dvb_ringbuffer_free);
263 EXPORT_SYMBOL(dvb_ringbuffer_avail);
264 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
265 EXPORT_SYMBOL(dvb_ringbuffer_read);
266 EXPORT_SYMBOL(dvb_ringbuffer_write);