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-rw-r--r--platforms/avr/timer.c133
1 files changed, 133 insertions, 0 deletions
diff --git a/platforms/avr/timer.c b/platforms/avr/timer.c
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+++ b/platforms/avr/timer.c
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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/>.
+*/
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/atomic.h>
+#include <stdint.h>
+#include "timer_avr.h"
+#include "timer.h"
+
+// counter resolution 1ms
+// NOTE: union { uint32_t timer32; struct { uint16_t dummy; uint16_t timer16; }}
+volatile uint32_t timer_count;
+
+/** \brief timer initialization
+ *
+ * FIXME: needs doc
+ */
+void timer_init(void) {
+#if TIMER_PRESCALER == 1
+ uint8_t prescaler = _BV(CS00);
+#elif TIMER_PRESCALER == 8
+ uint8_t prescaler = _BV(CS01);
+#elif TIMER_PRESCALER == 64
+ uint8_t prescaler = _BV(CS00) | _BV(CS01);
+#elif TIMER_PRESCALER == 256
+ uint8_t prescaler = _BV(CS02);
+#elif TIMER_PRESCALER == 1024
+ uint8_t prescaler = _BV(CS00) | _BV(CS02);
+#else
+# error "Timer prescaler value is not valid"
+#endif
+
+#if defined(__AVR_ATmega32A__)
+ // Timer0 CTC mode
+ TCCR0 = _BV(WGM01) | prescaler;
+
+ OCR0 = TIMER_RAW_TOP;
+ TIMSK = _BV(OCIE0);
+#elif defined(__AVR_ATtiny85__)
+ // Timer0 CTC mode
+ TCCR0A = _BV(WGM01);
+ TCCR0B = prescaler;
+
+ OCR0A = TIMER_RAW_TOP;
+ TIMSK = _BV(OCIE0A);
+#else
+ // Timer0 CTC mode
+ TCCR0A = _BV(WGM01);
+ TCCR0B = prescaler;
+
+ OCR0A = TIMER_RAW_TOP;
+ TIMSK0 = _BV(OCIE0A);
+#endif
+}
+
+/** \brief timer clear
+ *
+ * FIXME: needs doc
+ */
+inline void timer_clear(void) {
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { timer_count = 0; }
+}
+
+/** \brief timer read
+ *
+ * FIXME: needs doc
+ */
+inline uint16_t timer_read(void) {
+ uint32_t t;
+
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
+
+ return (t & 0xFFFF);
+}
+
+/** \brief timer read32
+ *
+ * FIXME: needs doc
+ */
+inline uint32_t timer_read32(void) {
+ uint32_t t;
+
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
+
+ return t;
+}
+
+/** \brief timer elapsed
+ *
+ * FIXME: needs doc
+ */
+inline uint16_t timer_elapsed(uint16_t last) {
+ uint32_t t;
+
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
+
+ return TIMER_DIFF_16((t & 0xFFFF), last);
+}
+
+/** \brief timer elapsed32
+ *
+ * FIXME: needs doc
+ */
+inline uint32_t timer_elapsed32(uint32_t last) {
+ uint32_t t;
+
+ ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
+
+ return TIMER_DIFF_32(t, last);
+}
+
+// excecuted once per 1ms.(excess for just timer count?)
+#ifndef __AVR_ATmega32A__
+# define TIMER_INTERRUPT_VECTOR TIMER0_COMPA_vect
+#else
+# define TIMER_INTERRUPT_VECTOR TIMER0_COMP_vect
+#endif
+ISR(TIMER_INTERRUPT_VECTOR, ISR_NOBLOCK) { timer_count++; }