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