From cefd0601b91fa642163c82021d454b3c17d8adf4 Mon Sep 17 00:00:00 2001
From: Jan Sucan <sucanjan@fit.cvut.cz>
Date: Sun, 22 Sep 2019 21:17:50 +0200
Subject: Initial commit

---
 FanController/fan_controller/delay.c | 113 +++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 FanController/fan_controller/delay.c

(limited to 'FanController/fan_controller/delay.c')

diff --git a/FanController/fan_controller/delay.c b/FanController/fan_controller/delay.c
new file mode 100644
index 0000000..9f793b9
--- /dev/null
+++ b/FanController/fan_controller/delay.c
@@ -0,0 +1,113 @@
+/* Autor: Ján Sučan <jan@jansucan.sk>
+ * 
+ * Zdrojove kody, ich casti a subory z nich vzniknute priamo alebo nepriamo
+ * (objektove subory, Intel Hex, ...) prosim nepouzivajte komercne, ani ako
+ * sucast komercnych diel. Vsetky ostatne pripady pouzitia su dovolene.
+ *
+ * Please don't use the source codes, their parts and files created from them
+ * directly or indirectly, (object files, Intel Hex files, ...) for commercial
+ * purposes, not even as a part of commercial products. All other use cases
+ * are allowed.
+ */
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+#include <fan_controller/delay.h>
+#include <fan_controller/error.h>
+
+/** Pocet milisekund pre jeden tik casovaca. */
+#define DELAY_MS_FOR_1_TIMER_TICK   16U // ms
+
+/** Pristup k hodnote systemoveho casu priamo bez zakazania presusenia (nie bezpecny). */
+#define DELAY_SYSTEM_TIME_UNSAFE    (delay_system_time)
+
+static uint32_t delay_get_system_time(void);
+
+/** Systemovy cas. Inkrementuje sa vzdy s kazdym pretecenim Casovaca 2. */
+static volatile uint32_t delay_system_time = 0;
+
+/**
+ * @brief Obsluha pretecenie Casovaca 2. Inkrementuje sa systemovy cas.
+ */
+ISR(TIMER2_OVF_vect)
+{
+	delay_system_time++;
+}
+
+/**
+ * @brief Inicializacia cakania a systemoveho casu.
+ */
+void
+delay_init(void)
+{
+	delay_system_time = 0;
+	// Enable interrupt
+	TIMSK |= (1 << TOIE2);	
+}
+
+/**
+ * @brief Blokujuce cakanie zadaneho poctu milisekund. Minimalna hodnota je 16.
+ * 
+ * @param ms Pocet milisekund ktore sa bude cakat.
+ */
+void
+delay_ms(unsigned int ms)
+{	
+	const uint32_t d = delay_get_deadline_ms(ms);
+	bool end_waiting = false;
+	
+	while (!end_waiting) {
+		// Aby sa nemuselo stale zakazovat a povolovat prerusenie, dosiahnutie konca cakanie sa detekuje najprv len priblizne
+		if (DELAY_SYSTEM_TIME_UNSAFE > d) {
+			// Potom sa skontroluje aj presne, tzn. hodnota systemoveho casovaca sa ziska so zakazanim prerusenia.
+			if (delay_get_system_time() > d) {
+				end_waiting = true;		
+			}
+		}
+	}
+}
+
+/**
+ * @brief Bezpecne ziskanie hodnoty systemoveho casu.
+ * 
+ * Zakaze sa prerusenie od Casovaca 2 pri pristupe k premennej zdielanej s obsluhou prerusenia.
+ *
+ * @return Hodnota systemoveho casovaca.
+ */
+uint32_t
+delay_get_system_time(void)
+{
+	TIMSK &= ~(1 << TOIE2);
+	const uint32_t t = DELAY_SYSTEM_TIME_UNSAFE;
+	TIMSK |= (1 << TOIE2);
+	return t;	
+}
+
+/**
+ * @brief Ziskanie buducej hodnoty systemoveho casu, ktora sa dosiahne za zadany pocet milisekund.
+ *
+ * @param ms Pocet milisekund pre cakanie. Minimalna hodnota je 16.
+ * @return Hodnota systemoveho casu, ktora sa dosiahne za zadany pocet milisekund.
+ */
+uint32_t
+delay_get_deadline_ms(uint16_t ms)
+{
+	if (ms < DELAY_MS_FOR_1_TIMER_TICK) {
+		error();
+	}
+	return (delay_get_system_time() + (ms / DELAY_MS_FOR_1_TIMER_TICK));
+}
+
+/**
+ * @brief Zistenie, ci bola prekrocena zadana hodnota systemoveho casovaca.
+ *
+ * @param deadline Hodnota systemoveho casu z funkcie delay_get_deadline_ms().
+ * @retval true Hodnota bola prekrocena.
+ * @retval false Hodnota nebola prekrocena.
+ */
+bool
+delay_has_deadline_expired(uint32_t deadline)
+{
+	return (delay_get_system_time() > deadline);
+}
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