mirror of
https://github.com/oliverschmidt/contiki.git
synced 2024-11-17 21:09:03 +00:00
107 lines
3.8 KiB
C
107 lines
3.8 KiB
C
/*
|
|
* Copyright (c) 2008, Swedish Institute of Computer Science.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the Institute nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* This file is part of the Contiki operating system.
|
|
*
|
|
*/
|
|
|
|
/**
|
|
* \file
|
|
* Ring buffer library implementation
|
|
* \author
|
|
* Adam Dunkels <adam@sics.se>
|
|
*/
|
|
|
|
#include "lib/ringbuf.h"
|
|
/*---------------------------------------------------------------------------*/
|
|
void
|
|
ringbuf_init(struct ringbuf *r, uint8_t *dataptr, uint8_t size)
|
|
{
|
|
r->data = dataptr;
|
|
r->mask = size - 1;
|
|
r->put_ptr = 0;
|
|
r->get_ptr = 0;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
int
|
|
ringbuf_put(struct ringbuf *r, uint8_t c)
|
|
{
|
|
/* Check if buffer is full. If it is full, return 0 to indicate that
|
|
the element was not inserted into the buffer.
|
|
|
|
XXX: there is a potential risk for a race condition here, because
|
|
the ->get_ptr field may be written concurrently by the
|
|
ringbuf_get() function. To avoid this, access to ->get_ptr must
|
|
be atomic. We use an uint8_t type, which makes access atomic on
|
|
most platforms, but C does not guarantee this.
|
|
*/
|
|
if(((r->put_ptr - r->get_ptr) & r->mask) == r->mask) {
|
|
return 0;
|
|
}
|
|
r->data[r->put_ptr] = c;
|
|
r->put_ptr = (r->put_ptr + 1) & r->mask;
|
|
return 1;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
int
|
|
ringbuf_get(struct ringbuf *r)
|
|
{
|
|
uint8_t c;
|
|
|
|
/* Check if there are bytes in the buffer. If so, we return the
|
|
first one and increase the pointer. If there are no bytes left, we
|
|
return -1.
|
|
|
|
XXX: there is a potential risk for a race condition here, because
|
|
the ->put_ptr field may be written concurrently by the
|
|
ringbuf_put() function. To avoid this, access to ->get_ptr must
|
|
be atomic. We use an uint8_t type, which makes access atomic on
|
|
most platforms, but C does not guarantee this.
|
|
*/
|
|
if(((r->put_ptr - r->get_ptr) & r->mask) > 0) {
|
|
c = r->data[r->get_ptr];
|
|
r->get_ptr = (r->get_ptr + 1) & r->mask;
|
|
return c;
|
|
} else {
|
|
return -1;
|
|
}
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
int
|
|
ringbuf_size(struct ringbuf *r)
|
|
{
|
|
return r->mask + 1;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
int
|
|
ringbuf_elements(struct ringbuf *r)
|
|
{
|
|
return (r->put_ptr - r->get_ptr) & r->mask;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|