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/* counter.c */
/*  {{{
 *
 * Copyright (C) 2004 Nicolas Schodet
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Contact :
 *        Web: http://perso.efrei.fr/~schodet/
 *      Email: <contact@ni.fr.eu.org>
 * }}} */
#include "counter.h"
#include <n/avr/utils/utils.h>

/* +AutoDec */
/* -AutoDec */

/** Forward and reverse counter value. */
static uint8_t counter_l_frw, counter_l_rev, counter_r_frw, counter_r_rev;
/** Last TCNT value. */
static uint8_t counter_l_old, counter_r_old;

/** Initialize the counters. */
inline void
counter_init (void)
{
    /* Left counter. */
    /*  External, rising edge. */
    TCCR2 = regv (FOC2, WGM20, COM21, COM20, WGM21, CS22, CS21, CS20,
		     0,     0,     0,     0,     0,    1,    1,    1);
    /* Right counter. */
    /*  Normal counter. */
    //TCCR3A = 0;
    /*  External, rising edge. */
    TCCR3B = regv (ICNC3, ICES3, 5, WGM33, WGM32, CS32, CS31, CS30,
		       0,     0, 0,	0,     0,    1,    1,    1);
    /* Begin with safe values. */
    counter_reset ();
}

/* Update counter, should be called as often as possible. */
inline void
counter_update (void)
{
    uint8_t c;
    /* Update left counter. */
    c = TCNT2;
    if (PINE & _BV (4))
      {
	PORTD &= ~0x40;
	counter_l_frw += c - counter_l_old;
      }
    else
      {
	PORTD |= 0x40;
	counter_l_rev += c - counter_l_old;
      }
    counter_l_old = c;
    /* Update right counter. */
    c = TCNT3L;
    if (PINE & _BV (5))
      {
	PORTD &= ~0x20;
	counter_r_frw += c - counter_r_old;
      }
    else
      {
	PORTD |= 0x20;
	counter_r_rev += c - counter_r_old;
      }
    counter_r_old = c;
}

/* Reset the counters. */
inline void
counter_reset (void)
{
    counter_l_frw = 0;
    counter_l_rev = 0;
    counter_l_old = TCNT2;
    counter_r_frw = 0;
    counter_r_rev = 0;
    counter_r_old = TCNT3L;
}