283c6e9339a4651b5b6c954e124d7e38025a1d0a
[linux-2.6.git] / 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 #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
43 void 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
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 }
91
92
93
94 void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
95 {
96         unsigned long flags;
97
98         spin_lock_irqsave(&rbuf->lock, flags);
99         dvb_ringbuffer_flush(rbuf);
100         spin_unlock_irqrestore(&rbuf->lock, flags);
101
102         wake_up(&rbuf->queue);
103 }
104
105
106
107 ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
108 {
109         size_t todo = len;
110         size_t split;
111
112         split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
113         if (split > 0) {
114                 if (!usermem)
115                         memcpy(buf, rbuf->data+rbuf->pread, split);
116                 else
117                         if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
118                                 return -EFAULT;
119                 buf += split;
120                 todo -= split;
121                 rbuf->pread = 0;
122         }
123         if (!usermem)
124                 memcpy(buf, rbuf->data+rbuf->pread, todo);
125         else
126                 if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
127                         return -EFAULT;
128
129         rbuf->pread = (rbuf->pread + todo) % rbuf->size;
130
131         return len;
132 }
133
134
135
136 ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
137 {
138         size_t todo = len;
139         size_t split;
140
141         split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
142
143         if (split > 0) {
144                 memcpy(rbuf->data+rbuf->pwrite, buf, split);
145                 buf += split;
146                 todo -= split;
147                 rbuf->pwrite = 0;
148         }
149         memcpy(rbuf->data+rbuf->pwrite, buf, todo);
150         rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;
151
152         return len;
153 }
154
155 ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
156 {
157         int status;
158         ssize_t oldpwrite = rbuf->pwrite;
159
160         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
161         DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
162         DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
163         status = dvb_ringbuffer_write(rbuf, buf, len);
164
165         if (status < 0) rbuf->pwrite = oldpwrite;
166         return status;
167 }
168
169 ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
170                                 int offset, u8* buf, size_t len, int usermem)
171 {
172         size_t todo;
173         size_t split;
174         size_t pktlen;
175
176         pktlen = rbuf->data[idx] << 8;
177         pktlen |= rbuf->data[(idx + 1) % rbuf->size];
178         if (offset > pktlen) return -EINVAL;
179         if ((offset + len) > pktlen) len = pktlen - offset;
180
181         idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
182         todo = len;
183         split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
184         if (split > 0) {
185                 if (!usermem)
186                         memcpy(buf, rbuf->data+idx, split);
187                 else
188                         if (copy_to_user(buf, rbuf->data+idx, split))
189                                 return -EFAULT;
190                 buf += split;
191                 todo -= split;
192                 idx = 0;
193         }
194         if (!usermem)
195                 memcpy(buf, rbuf->data+idx, todo);
196         else
197                 if (copy_to_user(buf, rbuf->data+idx, todo))
198                         return -EFAULT;
199
200         return len;
201 }
202
203 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
204 {
205         size_t pktlen;
206
207         rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
208
209         // clean up disposed packets
210         while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
211                 if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
212                         pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
213                         pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
214                         DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
215                 } else {
216                         // first packet is not disposed, so we stop cleaning now
217                         break;
218                 }
219         }
220 }
221
222 ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
223 {
224         int consumed;
225         int curpktlen;
226         int curpktstatus;
227
228         if (idx == -1) {
229                idx = rbuf->pread;
230         } else {
231                 curpktlen = rbuf->data[idx] << 8;
232                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
233                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
234         }
235
236         consumed = (idx - rbuf->pread) % rbuf->size;
237
238         while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
239
240                 curpktlen = rbuf->data[idx] << 8;
241                 curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
242                 curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
243
244                 if (curpktstatus == PKT_READY) {
245                         *pktlen = curpktlen;
246                         return idx;
247                 }
248
249                 consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
250                 idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
251         }
252
253         // no packets available
254         return -1;
255 }
256
257
258
259 EXPORT_SYMBOL(dvb_ringbuffer_init);
260 EXPORT_SYMBOL(dvb_ringbuffer_empty);
261 EXPORT_SYMBOL(dvb_ringbuffer_free);
262 EXPORT_SYMBOL(dvb_ringbuffer_avail);
263 EXPORT_SYMBOL(dvb_ringbuffer_flush);
264 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
265 EXPORT_SYMBOL(dvb_ringbuffer_read);
266 EXPORT_SYMBOL(dvb_ringbuffer_write);
267 EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
268 EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
269 EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
270 EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);