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/* pwm.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 "pwm.h"
#include <avr/io.h>

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

inline void
pwm_init (void)
{
    /* No timer/counter interrupt. */
    //TIMSK = 0;
    //ETIMSK = 0;
    /* Phase correct PWM, TOP = 0xff, OC1B & OC1C with positive logic.
       f_IO without prescaler.
       Fpwm = f_IO / (2 * prescaler * TOP) = 28912 Hz. */
    TCCR1A = _BV (COM1B1) | _BV (COM1C1) | _BV (WGM10);
    TCCR1B = _BV (CS10);
    /* Enable pwm and direction outputs in DDRB. */
    DDRB |= _BV (7) | _BV (6) | _BV (3) | _BV (2);
}

static inline int16_t
pwm_preproc (int16_t v)
{
    v = (v >> 2) + ((v >> 1) & 1);
    /*if (v > 0)
	v += 0x0f;
    else if (v < 0)
	v -= 0x0f;*/
    if (v > 255)
	return 255;
    else if (v < -255)
	return -255;
    else
	return v;
}

inline void
pwm_set_left (int16_t v)
{
    v = pwm_preproc (v);
    if (v < 0)
      {
	PORTB &= ~_BV (2);
	OCR1B = -v;
      }
    else
      {
	PORTB |= _BV (2);
	OCR1B = v;
      }
}

inline void
pwm_set_right (int16_t v)
{
    v = pwm_preproc (v);
    if (v < 0)
      {
	PORTB |= _BV (3);
	OCR1C = -v;
      }
    else
      {
	PORTB &= ~_BV (3);
	OCR1C = v;
      }
}