374 строки
10 KiB
C
374 строки
10 KiB
C
/*
|
|
*
|
|
* dvb_ringbuffer.c: ring buffer implementation for the dvb driver
|
|
*
|
|
* Copyright (C) 2003 Oliver Endriss
|
|
* Copyright (C) 2004 Andrew de Quincey
|
|
*
|
|
* based on code originally found in av7110.c & dvb_ci.c:
|
|
* Copyright (C) 1999-2003 Ralph Metzler
|
|
* & Marcus Metzler for convergence integrated media GmbH
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public License
|
|
* as published by the Free Software Foundation; either version 2.1
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*/
|
|
|
|
|
|
|
|
#include <linux/errno.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/string.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
#include "dvb_ringbuffer.h"
|
|
|
|
#define PKT_READY 0
|
|
#define PKT_DISPOSED 1
|
|
|
|
|
|
void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
|
|
{
|
|
rbuf->pread=rbuf->pwrite=0;
|
|
rbuf->data=data;
|
|
rbuf->size=len;
|
|
rbuf->error=0;
|
|
|
|
init_waitqueue_head(&rbuf->queue);
|
|
|
|
spin_lock_init(&(rbuf->lock));
|
|
}
|
|
|
|
|
|
|
|
int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
|
|
{
|
|
/* smp_load_acquire() to load write pointer on reader side
|
|
* this pairs with smp_store_release() in dvb_ringbuffer_write(),
|
|
* dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset()
|
|
*
|
|
* for memory barriers also see Documentation/circular-buffers.txt
|
|
*/
|
|
return (rbuf->pread == smp_load_acquire(&rbuf->pwrite));
|
|
}
|
|
|
|
|
|
|
|
ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
|
|
{
|
|
ssize_t free;
|
|
|
|
/* ACCESS_ONCE() to load read pointer on writer side
|
|
* this pairs with smp_store_release() in dvb_ringbuffer_read(),
|
|
* dvb_ringbuffer_read_user(), dvb_ringbuffer_flush(),
|
|
* or dvb_ringbuffer_reset()
|
|
*/
|
|
free = ACCESS_ONCE(rbuf->pread) - rbuf->pwrite;
|
|
if (free <= 0)
|
|
free += rbuf->size;
|
|
return free-1;
|
|
}
|
|
|
|
|
|
|
|
ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
|
|
{
|
|
ssize_t avail;
|
|
|
|
/* smp_load_acquire() to load write pointer on reader side
|
|
* this pairs with smp_store_release() in dvb_ringbuffer_write(),
|
|
* dvb_ringbuffer_write_user(), or dvb_ringbuffer_reset()
|
|
*/
|
|
avail = smp_load_acquire(&rbuf->pwrite) - rbuf->pread;
|
|
if (avail < 0)
|
|
avail += rbuf->size;
|
|
return avail;
|
|
}
|
|
|
|
|
|
|
|
void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
|
|
{
|
|
/* dvb_ringbuffer_flush() counts as read operation
|
|
* smp_load_acquire() to load write pointer
|
|
* smp_store_release() to update read pointer, this ensures that the
|
|
* correct pointer is visible for subsequent dvb_ringbuffer_free()
|
|
* calls on other cpu cores
|
|
*/
|
|
smp_store_release(&rbuf->pread, smp_load_acquire(&rbuf->pwrite));
|
|
rbuf->error = 0;
|
|
}
|
|
EXPORT_SYMBOL(dvb_ringbuffer_flush);
|
|
|
|
void dvb_ringbuffer_reset(struct dvb_ringbuffer *rbuf)
|
|
{
|
|
/* dvb_ringbuffer_reset() counts as read and write operation
|
|
* smp_store_release() to update read pointer
|
|
*/
|
|
smp_store_release(&rbuf->pread, 0);
|
|
/* smp_store_release() to update write pointer */
|
|
smp_store_release(&rbuf->pwrite, 0);
|
|
rbuf->error = 0;
|
|
}
|
|
|
|
void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&rbuf->lock, flags);
|
|
dvb_ringbuffer_flush(rbuf);
|
|
spin_unlock_irqrestore(&rbuf->lock, flags);
|
|
|
|
wake_up(&rbuf->queue);
|
|
}
|
|
|
|
ssize_t dvb_ringbuffer_read_user(struct dvb_ringbuffer *rbuf, u8 __user *buf, size_t len)
|
|
{
|
|
size_t todo = len;
|
|
size_t split;
|
|
|
|
split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
|
|
if (split > 0) {
|
|
if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
|
|
return -EFAULT;
|
|
buf += split;
|
|
todo -= split;
|
|
/* smp_store_release() for read pointer update to ensure
|
|
* that buf is not overwritten until read is complete,
|
|
* this pairs with ACCESS_ONCE() in dvb_ringbuffer_free()
|
|
*/
|
|
smp_store_release(&rbuf->pread, 0);
|
|
}
|
|
if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
|
|
return -EFAULT;
|
|
|
|
/* smp_store_release() to update read pointer, see above */
|
|
smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size);
|
|
|
|
return len;
|
|
}
|
|
|
|
void dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len)
|
|
{
|
|
size_t todo = len;
|
|
size_t split;
|
|
|
|
split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
|
|
if (split > 0) {
|
|
memcpy(buf, rbuf->data+rbuf->pread, split);
|
|
buf += split;
|
|
todo -= split;
|
|
/* smp_store_release() for read pointer update to ensure
|
|
* that buf is not overwritten until read is complete,
|
|
* this pairs with ACCESS_ONCE() in dvb_ringbuffer_free()
|
|
*/
|
|
smp_store_release(&rbuf->pread, 0);
|
|
}
|
|
memcpy(buf, rbuf->data+rbuf->pread, todo);
|
|
|
|
/* smp_store_release() to update read pointer, see above */
|
|
smp_store_release(&rbuf->pread, (rbuf->pread + todo) % rbuf->size);
|
|
}
|
|
|
|
|
|
ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
|
|
{
|
|
size_t todo = len;
|
|
size_t split;
|
|
|
|
split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
|
|
|
|
if (split > 0) {
|
|
memcpy(rbuf->data+rbuf->pwrite, buf, split);
|
|
buf += split;
|
|
todo -= split;
|
|
/* smp_store_release() for write pointer update to ensure that
|
|
* written data is visible on other cpu cores before the pointer
|
|
* update, this pairs with smp_load_acquire() in
|
|
* dvb_ringbuffer_empty() or dvb_ringbuffer_avail()
|
|
*/
|
|
smp_store_release(&rbuf->pwrite, 0);
|
|
}
|
|
memcpy(rbuf->data+rbuf->pwrite, buf, todo);
|
|
/* smp_store_release() for write pointer update, see above */
|
|
smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size);
|
|
|
|
return len;
|
|
}
|
|
|
|
ssize_t dvb_ringbuffer_write_user(struct dvb_ringbuffer *rbuf,
|
|
const u8 __user *buf, size_t len)
|
|
{
|
|
int status;
|
|
size_t todo = len;
|
|
size_t split;
|
|
|
|
split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;
|
|
|
|
if (split > 0) {
|
|
status = copy_from_user(rbuf->data+rbuf->pwrite, buf, split);
|
|
if (status)
|
|
return len - todo;
|
|
buf += split;
|
|
todo -= split;
|
|
/* smp_store_release() for write pointer update to ensure that
|
|
* written data is visible on other cpu cores before the pointer
|
|
* update, this pairs with smp_load_acquire() in
|
|
* dvb_ringbuffer_empty() or dvb_ringbuffer_avail()
|
|
*/
|
|
smp_store_release(&rbuf->pwrite, 0);
|
|
}
|
|
status = copy_from_user(rbuf->data+rbuf->pwrite, buf, todo);
|
|
if (status)
|
|
return len - todo;
|
|
/* smp_store_release() for write pointer update, see above */
|
|
smp_store_release(&rbuf->pwrite, (rbuf->pwrite + todo) % rbuf->size);
|
|
|
|
return len;
|
|
}
|
|
|
|
ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
|
|
{
|
|
int status;
|
|
ssize_t oldpwrite = rbuf->pwrite;
|
|
|
|
DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
|
|
DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
|
|
DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
|
|
status = dvb_ringbuffer_write(rbuf, buf, len);
|
|
|
|
if (status < 0) rbuf->pwrite = oldpwrite;
|
|
return status;
|
|
}
|
|
|
|
ssize_t dvb_ringbuffer_pkt_read_user(struct dvb_ringbuffer *rbuf, size_t idx,
|
|
int offset, u8 __user *buf, size_t len)
|
|
{
|
|
size_t todo;
|
|
size_t split;
|
|
size_t pktlen;
|
|
|
|
pktlen = rbuf->data[idx] << 8;
|
|
pktlen |= rbuf->data[(idx + 1) % rbuf->size];
|
|
if (offset > pktlen) return -EINVAL;
|
|
if ((offset + len) > pktlen) len = pktlen - offset;
|
|
|
|
idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
|
|
todo = len;
|
|
split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
|
|
if (split > 0) {
|
|
if (copy_to_user(buf, rbuf->data+idx, split))
|
|
return -EFAULT;
|
|
buf += split;
|
|
todo -= split;
|
|
idx = 0;
|
|
}
|
|
if (copy_to_user(buf, rbuf->data+idx, todo))
|
|
return -EFAULT;
|
|
|
|
return len;
|
|
}
|
|
|
|
ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
|
|
int offset, u8* buf, size_t len)
|
|
{
|
|
size_t todo;
|
|
size_t split;
|
|
size_t pktlen;
|
|
|
|
pktlen = rbuf->data[idx] << 8;
|
|
pktlen |= rbuf->data[(idx + 1) % rbuf->size];
|
|
if (offset > pktlen) return -EINVAL;
|
|
if ((offset + len) > pktlen) len = pktlen - offset;
|
|
|
|
idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
|
|
todo = len;
|
|
split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
|
|
if (split > 0) {
|
|
memcpy(buf, rbuf->data+idx, split);
|
|
buf += split;
|
|
todo -= split;
|
|
idx = 0;
|
|
}
|
|
memcpy(buf, rbuf->data+idx, todo);
|
|
return len;
|
|
}
|
|
|
|
void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
|
|
{
|
|
size_t pktlen;
|
|
|
|
rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;
|
|
|
|
// clean up disposed packets
|
|
while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
|
|
if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
|
|
pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
|
|
pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
|
|
DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
|
|
} else {
|
|
// first packet is not disposed, so we stop cleaning now
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
|
|
{
|
|
int consumed;
|
|
int curpktlen;
|
|
int curpktstatus;
|
|
|
|
if (idx == -1) {
|
|
idx = rbuf->pread;
|
|
} else {
|
|
curpktlen = rbuf->data[idx] << 8;
|
|
curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
|
|
idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
|
|
}
|
|
|
|
consumed = (idx - rbuf->pread) % rbuf->size;
|
|
|
|
while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
|
|
|
|
curpktlen = rbuf->data[idx] << 8;
|
|
curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
|
|
curpktstatus = rbuf->data[(idx + 2) % rbuf->size];
|
|
|
|
if (curpktstatus == PKT_READY) {
|
|
*pktlen = curpktlen;
|
|
return idx;
|
|
}
|
|
|
|
consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
|
|
idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
|
|
}
|
|
|
|
// no packets available
|
|
return -1;
|
|
}
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(dvb_ringbuffer_init);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_empty);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_free);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_avail);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_read_user);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_read);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_write);
|
|
EXPORT_SYMBOL(dvb_ringbuffer_write_user);
|