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);
267
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