1 files changed, 53 insertions, 0 deletions
diff --git a/common/timer.h b/common/timer.h
new file mode 100644
index 0000000000..f9e8181e6f
--- /dev/null
+++ b/common/timer.h
@@ -0,0 +1,53 @@
+/*
+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