/* buffer.c - implementacao do buffer circular
 * (c) AC - 2008-2011 - LEI - DI-FCT/UNL
 */

#include <stdio.h>
#include <stdlib.h>

#include "bufcirc.h"

#define MAX	1024

int put;		/* onde se inserem novos caracteres */
int get;		/* de onde se retiram caracteres */
int nc;		/* numero de caracteres no buffer */
char buffer[MAX];/* o buffer */

void fatal_error( char *s )
{
	fprintf( stderr, "ERRO: %s\n", s );
	exit(1);
}

void buf_init(void)
{
	put = 0;
	get = 0;
	nc = 0;
}

void buf_put( char c )
{
	if( buf_full() )
		fatal_error( "buf_put com buffer cheio" );

	buffer[put] = c;
	put = (put + 1) % MAX ;
	nc++ ;
}

char buf_get( void )
{
	char c;

	if( buf_empty() )
		fatal_error( "buf_get com buffer vazio" );
	
	c = buffer[get];
	get = (get + 1) % MAX ;
	nc-- ;

	return c;
}

int buf_empty( void )
{	return (nc == 0);
}

int buf_full( void )
{	return (nc == MAX);
}