/*
* Copyright (c) 2017 Jiri Svoboda
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
/** @addtogroup libc
* @{
*/
/** @file Circular buffer
*/
#include <adt/circ_buf.h>
#include <errno.h>
#include <mem.h>
#include <stddef.h>
/** Initialize circular buffer.
*
* @param cbuf Circular buffer
* @param buf Buffer for storing data
* @param nmemb Number of entries in @a buf
* @param size Size of individual buffer entry
*/
void circ_buf_init(circ_buf_t *cbuf, void *buf, size_t nmemb, size_t size)
{
cbuf->buf = buf;
cbuf->nmemb = nmemb;
cbuf->size = size;
cbuf->rp = 0;
cbuf->wp = 0;
cbuf->nused = 0;
}
/** Return number of free buffer entries.
*
* @param cbuf Circular buffer
* @return Number of free buffer entries
*/
size_t circ_buf_nfree(circ_buf_t *cbuf)
{
return cbuf->nmemb - cbuf->nused;
}
/** Return number of used buffer entries.
*
* @param cbuf Circular buffer
* @return Number of used buffer entries
*/
size_t circ_buf_nused(circ_buf_t *cbuf)
{
return cbuf->nused;
}
/** Push new entry into circular buffer.
*
* @param cbuf Circular buffer
* @param data Pointer to entry data
* @return EOK on success, EAGAIN if circular buffer is full
*/
errno_t circ_buf_push(circ_buf_t *cbuf, const void *data)
{
if (circ_buf_nfree(cbuf) == 0)
return EAGAIN;
memcpy(cbuf->buf + cbuf->size * cbuf->wp, data, cbuf->size);
cbuf->wp = (cbuf->wp + 1) % cbuf->nmemb;
cbuf->nused++;
return EOK;
}
/** Pop entry from circular buffer.
*
* @param cbuf Circular buffer
* @param datab Pointer to data buffer for storing entry
* @return EOK on success, EAGAIN if circular buffer is full
*/
errno_t circ_buf_pop(circ_buf_t *cbuf, void *datab)
{
if (cbuf->nused == 0)
return EAGAIN;
memcpy(datab, cbuf->buf + cbuf->size * cbuf->rp, cbuf->size);
cbuf->rp = (cbuf->rp + 1) % cbuf->nmemb;
cbuf->nused--;
return EOK;
}
/** @}
*/