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/*
Copyright 2011 Jun Wako <wakojun@gmail.com>
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, see <http://www.gnu.org/licenses/>.
*/
#ifndef TIMER_H
#define TIMER_H 1
#include <stdint.h>
#ifndef TIMER_PRESCALER
# if F_CPU > 16000000
# define TIMER_PRESCALER 256
# elif F_CPU >= 4000000
# define TIMER_PRESCALER 64
# else
# define TIMER_PRESCALER 8
# endif
#endif
#define TIMER_RAW_FREQ (F_CPU/TIMER_PRESCALER)
#define TIMER_RAW TCNT0
#define TIMER_RAW_TOP (TIMER_RAW_FREQ/1000)
#if (TIMER_RAW_TOP > 255)
# error "Timer0 can't count 1ms at this clock freq. Use larger prescaler."
#endif
#define TIMER_DIFF(a, b, max) ((a) >= (b) ? (a) - (b) : (max) - (b) + (a))
#define TIMER_DIFF_RAW(a, b) TIMER_DIFF(a, b, UINT8_MAX)
#define TIMER_DIFF_MS(a, b) TIMER_DIFF(a, b, UINT16_MAX)
extern volatile uint16_t timer_count;
void timer_init(void);
void timer_clear(void);
uint16_t timer_read(void);
uint16_t timer_elapsed(uint16_t last);
#endif
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