dvb_ringbuffer.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
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
43void 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
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}
91
92
93
94void 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
107ssize_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
136ssize_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
155ssize_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
169ssize_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
203void 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
222ssize_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
259EXPORT_SYMBOL(dvb_ringbuffer_init);
260EXPORT_SYMBOL(dvb_ringbuffer_empty);
261EXPORT_SYMBOL(dvb_ringbuffer_free);
262EXPORT_SYMBOL(dvb_ringbuffer_avail);
263EXPORT_SYMBOL(dvb_ringbuffer_flush);
264EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
265EXPORT_SYMBOL(dvb_ringbuffer_read);
266EXPORT_SYMBOL(dvb_ringbuffer_write);
267EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
268EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
269EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
270EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);
271