1 files changed, 61 insertions, 0 deletions
diff --git a/avr/timer.c b/avr/timer.c
new file mode 100644
index 0000000..1b15985
--- /dev/null
+++ b/avr/timer.c
@@ -0,0 +1,61 @@
+/*
+ * (C) Copyright 2014 Leo C. <erbl259-lmu@yahoo.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include "timer.h"
+#include <avr/interrupt.h>
+#include <util/atomic.h>
+#include "time.h"
+
+/* timer interrupt/overflow counter */
+/* counts up every ms. */
+static volatile
+uint32_t timestamp;
+
+/*
+ * 1000Hz timer interrupt generated by OC4A
+ */
+ISR(TIMER4_COMPA_vect)
+{
+	static int_fast8_t tick_10ms;
+	static int_fast8_t tick_1s;
+	int_fast8_t i, j;
+
+	extern void disk_timerproc(void);
+
+	OCR4A += F_CPU / 1000;	/* 1000Hz interval */
+
+	timestamp++;
+
+	i = tick_10ms + 1;
+	if (i == 10) {
+		Stat |= S_10MS_TO;
+
+		/* Drive timer procedure of low level disk I/O module */
+		disk_timerproc();
+
+		j = tick_1s - 1;
+		if (j == 0) {
+			system_tick();
+			j = 100;
+		}
+		tick_1s = j;
+		i = 0;
+	}
+	tick_10ms = i;
+}
+
+
+/*--------------------------------------------------------------------------*/
+
+uint32_t get_timer(uint32_t base)
+{
+	uint32_t ret;
+	ATOMIC_BLOCK(ATOMIC_FORCEON)
+	{
+		ret = timestamp;
+	}
+	return ret - base;
+}