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/****************************************************************************
*
* Copyright (c) 2013 PX4 Development Team. All rights reserved.
* Author: Anton Babushkin <anton.babushkin@me.com>
*
* 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 PX4 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 COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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.
*
****************************************************************************/
/**
* @file logbuffer.c
*
* Ring FIFO buffer for binary log data.
*
* @author Anton Babushkin <anton.babushkin@me.com>
*/
#include <string.h>
#include <stdlib.h>
#include "logbuffer.h"
int logbuffer_init(struct logbuffer_s *lb, int size)
{
lb->size = size;
lb->write_ptr = 0;
lb->read_ptr = 0;
lb->data = malloc(lb->size);
return (lb->data == 0) ? ERROR : OK;
}
int logbuffer_count(struct logbuffer_s *lb)
{
int n = lb->write_ptr - lb->read_ptr;
if (n < 0) {
n += lb->size;
}
return n;
}
int logbuffer_is_empty(struct logbuffer_s *lb)
{
return lb->read_ptr == lb->write_ptr;
}
bool logbuffer_write(struct logbuffer_s *lb, void *ptr, int size)
{
// bytes available to write
int available = lb->read_ptr - lb->write_ptr - 1;
if (available < 0)
available += lb->size;
if (size > available) {
// buffer overflow
return false;
}
char *c = (char *) ptr;
int n = lb->size - lb->write_ptr; // bytes to end of the buffer
if (n < size) {
// message goes over end of the buffer
memcpy(&(lb->data[lb->write_ptr]), c, n);
lb->write_ptr = 0;
} else {
n = 0;
}
// now: n = bytes already written
int p = size - n; // number of bytes to write
memcpy(&(lb->data[lb->write_ptr]), &(c[n]), p);
lb->write_ptr = (lb->write_ptr + p) % lb->size;
return true;
}
int logbuffer_get_ptr(struct logbuffer_s *lb, void **ptr, bool *is_part)
{
// bytes available to read
int available = lb->write_ptr - lb->read_ptr;
if (available == 0) {
return 0; // buffer is empty
}
int n = 0;
if (available > 0) {
// read pointer is before write pointer, all available bytes can be read
n = available;
*is_part = false;
} else {
// read pointer is after write pointer, read bytes from read_ptr to end of the buffer
n = lb->size - lb->read_ptr;
*is_part = lb->write_ptr > 0;
}
*ptr = &(lb->data[lb->read_ptr]);
return n;
}
void logbuffer_mark_read(struct logbuffer_s *lb, int n)
{
lb->read_ptr = (lb->read_ptr + n) % lb->size;
}
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