3 * dvb_ringbuffer.c: ring buffer implementation for the dvb driver
5 * Copyright (C) 2003 Oliver Endriss
6 * Copyright (C) 2004 Andrew de Quincey
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
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.
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.
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.
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>
36 #include "dvb_ringbuffer.h"
39 #define PKT_DISPOSED 1
42 void dvb_ringbuffer_init(struct dvb_ringbuffer
*rbuf
, void *data
, size_t len
)
44 rbuf
->pread
=rbuf
->pwrite
=0;
49 init_waitqueue_head(&rbuf
->queue
);
51 spin_lock_init(&(rbuf
->lock
));
56 int dvb_ringbuffer_empty(struct dvb_ringbuffer
*rbuf
)
58 /* smp_load_acquire() to load write pointer on reader side
59 * this pairs with smp_store_release() in dvb_ringbuffer_write(),
60 * dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset()
62 * for memory barriers also see Documentation/circular-buffers.txt
64 return (rbuf
->pread
== smp_load_acquire(&rbuf
->pwrite
));
69 ssize_t
dvb_ringbuffer_free(struct dvb_ringbuffer
*rbuf
)
73 /* ACCESS_ONCE() to load read pointer on writer side
74 * this pairs with smp_store_release() in dvb_ringbuffer_read(),
75 * dvb_ringbuffer_read_user(), dvb_ringbuffer_flush(),
76 * or dvb_ringbuffer_reset()
78 free
= ACCESS_ONCE(rbuf
->pread
) - rbuf
->pwrite
;
86 ssize_t
dvb_ringbuffer_avail(struct dvb_ringbuffer
*rbuf
)
90 /* smp_load_acquire() to load write pointer on reader side
91 * this pairs with smp_store_release() in dvb_ringbuffer_write(),
92 * dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset()
94 avail
= smp_load_acquire(&rbuf
->pwrite
) - rbuf
->pread
;
102 void dvb_ringbuffer_flush(struct dvb_ringbuffer
*rbuf
)
104 /* dvb_ringbuffer_flush() counts as read operation
105 * smp_load_acquire() to load write pointer
106 * smp_store_release() to update read pointer, this ensures that the
107 * correct pointer is visible for subsequent dvb_ringbuffer_free()
108 * calls on other cpu cores
110 smp_store_release(&rbuf
->pread
, smp_load_acquire(&rbuf
->pwrite
));
113 EXPORT_SYMBOL(dvb_ringbuffer_flush
);
115 void dvb_ringbuffer_reset(struct dvb_ringbuffer
*rbuf
)
117 /* dvb_ringbuffer_reset() counts as read and write operation
118 * smp_store_release() to update read pointer
120 smp_store_release(&rbuf
->pread
, 0);
121 /* smp_store_release() to update write pointer */
122 smp_store_release(&rbuf
->pwrite
, 0);
126 void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer
*rbuf
)
130 spin_lock_irqsave(&rbuf
->lock
, flags
);
131 dvb_ringbuffer_flush(rbuf
);
132 spin_unlock_irqrestore(&rbuf
->lock
, flags
);
134 wake_up(&rbuf
->queue
);
137 ssize_t
dvb_ringbuffer_read_user(struct dvb_ringbuffer
*rbuf
, u8 __user
*buf
, size_t len
)
142 split
= (rbuf
->pread
+ len
> rbuf
->size
) ? rbuf
->size
- rbuf
->pread
: 0;
144 if (copy_to_user(buf
, rbuf
->data
+rbuf
->pread
, split
))
148 /* smp_store_release() for read pointer update to ensure
149 * that buf is not overwritten until read is complete,
150 * this pairs with ACCESS_ONCE() in dvb_ringbuffer_free()
152 smp_store_release(&rbuf
->pread
, 0);
154 if (copy_to_user(buf
, rbuf
->data
+rbuf
->pread
, todo
))
157 /* smp_store_release() to update read pointer, see above */
158 smp_store_release(&rbuf
->pread
, (rbuf
->pread
+ todo
) % rbuf
->size
);
163 void dvb_ringbuffer_read(struct dvb_ringbuffer
*rbuf
, u8
*buf
, size_t len
)
168 split
= (rbuf
->pread
+ len
> rbuf
->size
) ? rbuf
->size
- rbuf
->pread
: 0;
170 memcpy(buf
, rbuf
->data
+rbuf
->pread
, split
);
173 /* smp_store_release() for read pointer update to ensure
174 * that buf is not overwritten until read is complete,
175 * this pairs with ACCESS_ONCE() in dvb_ringbuffer_free()
177 smp_store_release(&rbuf
->pread
, 0);
179 memcpy(buf
, rbuf
->data
+rbuf
->pread
, todo
);
181 /* smp_store_release() to update read pointer, see above */
182 smp_store_release(&rbuf
->pread
, (rbuf
->pread
+ todo
) % rbuf
->size
);
186 ssize_t
dvb_ringbuffer_write(struct dvb_ringbuffer
*rbuf
, const u8
*buf
, size_t len
)
191 split
= (rbuf
->pwrite
+ len
> rbuf
->size
) ? rbuf
->size
- rbuf
->pwrite
: 0;
194 memcpy(rbuf
->data
+rbuf
->pwrite
, buf
, split
);
197 /* smp_store_release() for write pointer update to ensure that
198 * written data is visible on other cpu cores before the pointer
199 * update, this pairs with smp_load_acquire() in
200 * dvb_ringbuffer_empty() or dvb_ringbuffer_avail()
202 smp_store_release(&rbuf
->pwrite
, 0);
204 memcpy(rbuf
->data
+rbuf
->pwrite
, buf
, todo
);
205 /* smp_store_release() for write pointer update, see above */
206 smp_store_release(&rbuf
->pwrite
, (rbuf
->pwrite
+ todo
) % rbuf
->size
);
211 ssize_t
dvb_ringbuffer_write_user(struct dvb_ringbuffer
*rbuf
,
212 const u8 __user
*buf
, size_t len
)
218 split
= (rbuf
->pwrite
+ len
> rbuf
->size
) ? rbuf
->size
- rbuf
->pwrite
: 0;
221 status
= copy_from_user(rbuf
->data
+rbuf
->pwrite
, buf
, split
);
226 /* smp_store_release() for write pointer update to ensure that
227 * written data is visible on other cpu cores before the pointer
228 * update, this pairs with smp_load_acquire() in
229 * dvb_ringbuffer_empty() or dvb_ringbuffer_avail()
231 smp_store_release(&rbuf
->pwrite
, 0);
233 status
= copy_from_user(rbuf
->data
+rbuf
->pwrite
, buf
, todo
);
236 /* smp_store_release() for write pointer update, see above */
237 smp_store_release(&rbuf
->pwrite
, (rbuf
->pwrite
+ todo
) % rbuf
->size
);
242 ssize_t
dvb_ringbuffer_pkt_write(struct dvb_ringbuffer
*rbuf
, u8
* buf
, size_t len
)
245 ssize_t oldpwrite
= rbuf
->pwrite
;
247 DVB_RINGBUFFER_WRITE_BYTE(rbuf
, len
>> 8);
248 DVB_RINGBUFFER_WRITE_BYTE(rbuf
, len
& 0xff);
249 DVB_RINGBUFFER_WRITE_BYTE(rbuf
, PKT_READY
);
250 status
= dvb_ringbuffer_write(rbuf
, buf
, len
);
252 if (status
< 0) rbuf
->pwrite
= oldpwrite
;
256 ssize_t
dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer
*rbuf
, size_t idx
,
257 int offset
, u8 __user
*buf
, size_t len
)
263 pktlen
= rbuf
->data
[idx
] << 8;
264 pktlen
|= rbuf
->data
[(idx
+ 1) % rbuf
->size
];
265 if (offset
> pktlen
) return -EINVAL
;
266 if ((offset
+ len
) > pktlen
) len
= pktlen
- offset
;
268 idx
= (idx
+ DVB_RINGBUFFER_PKTHDRSIZE
+ offset
) % rbuf
->size
;
270 split
= ((idx
+ len
) > rbuf
->size
) ? rbuf
->size
- idx
: 0;
272 if (copy_to_user(buf
, rbuf
->data
+idx
, split
))
278 if (copy_to_user(buf
, rbuf
->data
+idx
, todo
))
284 ssize_t
dvb_ringbuffer_pkt_read(struct dvb_ringbuffer
*rbuf
, size_t idx
,
285 int offset
, u8
* buf
, size_t len
)
291 pktlen
= rbuf
->data
[idx
] << 8;
292 pktlen
|= rbuf
->data
[(idx
+ 1) % rbuf
->size
];
293 if (offset
> pktlen
) return -EINVAL
;
294 if ((offset
+ len
) > pktlen
) len
= pktlen
- offset
;
296 idx
= (idx
+ DVB_RINGBUFFER_PKTHDRSIZE
+ offset
) % rbuf
->size
;
298 split
= ((idx
+ len
) > rbuf
->size
) ? rbuf
->size
- idx
: 0;
300 memcpy(buf
, rbuf
->data
+idx
, split
);
305 memcpy(buf
, rbuf
->data
+idx
, todo
);
309 void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer
*rbuf
, size_t idx
)
313 rbuf
->data
[(idx
+ 2) % rbuf
->size
] = PKT_DISPOSED
;
315 // clean up disposed packets
316 while(dvb_ringbuffer_avail(rbuf
) > DVB_RINGBUFFER_PKTHDRSIZE
) {
317 if (DVB_RINGBUFFER_PEEK(rbuf
, 2) == PKT_DISPOSED
) {
318 pktlen
= DVB_RINGBUFFER_PEEK(rbuf
, 0) << 8;
319 pktlen
|= DVB_RINGBUFFER_PEEK(rbuf
, 1);
320 DVB_RINGBUFFER_SKIP(rbuf
, pktlen
+ DVB_RINGBUFFER_PKTHDRSIZE
);
322 // first packet is not disposed, so we stop cleaning now
328 ssize_t
dvb_ringbuffer_pkt_next(struct dvb_ringbuffer
*rbuf
, size_t idx
, size_t* pktlen
)
337 curpktlen
= rbuf
->data
[idx
] << 8;
338 curpktlen
|= rbuf
->data
[(idx
+ 1) % rbuf
->size
];
339 idx
= (idx
+ curpktlen
+ DVB_RINGBUFFER_PKTHDRSIZE
) % rbuf
->size
;
342 consumed
= (idx
- rbuf
->pread
) % rbuf
->size
;
344 while((dvb_ringbuffer_avail(rbuf
) - consumed
) > DVB_RINGBUFFER_PKTHDRSIZE
) {
346 curpktlen
= rbuf
->data
[idx
] << 8;
347 curpktlen
|= rbuf
->data
[(idx
+ 1) % rbuf
->size
];
348 curpktstatus
= rbuf
->data
[(idx
+ 2) % rbuf
->size
];
350 if (curpktstatus
== PKT_READY
) {
355 consumed
+= curpktlen
+ DVB_RINGBUFFER_PKTHDRSIZE
;
356 idx
= (idx
+ curpktlen
+ DVB_RINGBUFFER_PKTHDRSIZE
) % rbuf
->size
;
359 // no packets available
365 EXPORT_SYMBOL(dvb_ringbuffer_init
);
366 EXPORT_SYMBOL(dvb_ringbuffer_empty
);
367 EXPORT_SYMBOL(dvb_ringbuffer_free
);
368 EXPORT_SYMBOL(dvb_ringbuffer_avail
);
369 EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup
);
370 EXPORT_SYMBOL(dvb_ringbuffer_read_user
);
371 EXPORT_SYMBOL(dvb_ringbuffer_read
);
372 EXPORT_SYMBOL(dvb_ringbuffer_write
);
373 EXPORT_SYMBOL(dvb_ringbuffer_write_user
);