circular_buffer.c

/*
Copyright (C) 2013  
Fabien Gaud <fgaud@sfu.ca>, Baptiste Lepers <baptiste.lepers@inria.fr>,
Fabien Mottet <fabien.mottet@inria.fr>

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
version 2 or later, as published by the Free Software Foundation.

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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

#include "circular_buffer.h"
#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <stdlib.h>

/******************open_circ********************/
circularBuffer * open_circ(circularBuffer *cb, int size){
	
	if(cb == NULL){
		return NULL;
	}
	
	
	cb->buffer = (int *)malloc((size+1) * sizeof(int));
	
		
	if(cb->buffer == NULL)
	{
		return NULL;
	}
	else
	{
		bzero(cb->buffer, (size+1) * sizeof(int));
		cb->readPos = 0;
		cb->writePos = 0;
		cb->size = size + 1;
	}
	
	return(cb);
}

void close_circ(circularBuffer *cb){
	
	if(cb == NULL){
		return;
	}

	free(cb->buffer);
	cb->readPos = 0;
	cb->writePos = 0;
	cb->size = 0;
}


/******************get_circ********************/
int get_circ(circularBuffer *cb){
	
	int retValue;
	//empty buffer
	if(cb->readPos == cb->writePos)
		return(CIRC_BUF_ERROR);
	
	retValue = cb->buffer[cb->readPos];
	
	//Increment readPos and return the value pointed by it.
	if(++(cb->readPos)==cb->size)
		cb->readPos = 0;
	
	
	return retValue;
	
}


/******************put_circ********************/
int put_circ(circularBuffer *cb, int e){
	int p;
	
	//get where we will write
	p = cb->writePos + 1;
	
	//check if it's a valid position to write to
	if (p == cb->size)
	{
		p = 0;
	}
	if (p == cb->readPos)
	{
		return(CIRC_BUF_ERROR);
	}
	
	//If position is ok, we write the data and writePos goes to the next step.
	cb->buffer[cb->writePos] = e;
	cb->writePos = p;
	
	return (e);
}


/******************printfCircularBuffer********************/
void printfCircularBuffer(circularBuffer* cb ){
		int i;
		int size = (int)cb->size;		
		
		printf("circBuffer-> size:%d, read_pos:%d, write_pos:%d\n", size, cb->readPos, cb->writePos);
		
		for(i=0 ; i< (size); i++){
		printf("\t|%d", cb->buffer[i]);	
		}
		printf("\t|\n");
		for(i=0 ; i< (size); i++){
			printf("\t");
			if( i == cb->readPos && i == cb->writePos){
				printf(" rw");
			}	
			else if( i == cb->writePos){
				printf(" w");
			}
			else if( i == cb->readPos){
				printf(" r");
			}
		}
		printf("\n");
	}


//EOF