From 51af35ffc632f7979fecc609445af8378466d405 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Sat, 4 Dec 2021 18:00:23 -0700
Subject: Created basic Mutex

---
 src/sys/timer.c  | 25 ++++++++++++++++++++-----
 src/util/mutex.c | 20 ++++++++++++++++++++
 src/util/mutex.h | 15 +++++++++++++++
 3 files changed, 55 insertions(+), 5 deletions(-)
 create mode 100644 src/util/mutex.c
 create mode 100644 src/util/mutex.h

(limited to 'src')

diff --git a/src/sys/timer.c b/src/sys/timer.c
index 6996983..16e6fdb 100644
--- a/src/sys/timer.c
+++ b/src/sys/timer.c
@@ -1,17 +1,32 @@
 #include "../sys/core.h"
 #include "../sys/timer.h"
 #include "../util/time.h"
+#include "../util/mutex.h"
 #include "../drivers/uart.a.h"
 #include "../drivers/uart.h"
 
+static unsigned long exe_cnt = 0;
+static struct Mutex exe_cnt_m = {.addr = &exe_cnt, .pid = NULL_PID};
+
+//static unsigned long execution_count = 0;
+
 void c_timer() {
 	// Reset the counter
 	write_cntv_tval(cntfrq);
 
 	// Output the value
-	uart_string((char*)"Timer Value: ");
-	unsigned long v = read_cntv_tval();
-	uart_10(v);
-	uart_char(0x20);
-	uart_hexn(v);
+	//uart_string((char*)"Timer Value: ");
+	//unsigned long v = read_cntv_tval();
+	//uart_10(v);
+	//uart_char(0x20);
+	//uart_hexn(v);
+
+	// Lock the execution counter
+	if (lock_mutex(&exe_cnt_m, SCHED_PID) == 0) {
+		*(exe_cnt_m.addr) += 1;
+		uart_string((char*)"Executed #");
+		uart_10(*(exe_cnt_m.addr));
+		uart_string((char*)" Times\n");
+		release_mutex(&exe_cnt_m, SCHED_PID);
+	}
 }
diff --git a/src/util/mutex.c b/src/util/mutex.c
new file mode 100644
index 0000000..86ffcf5
--- /dev/null
+++ b/src/util/mutex.c
@@ -0,0 +1,20 @@
+#include "../util/mutex.h"
+
+unsigned char lock_mutex(struct Mutex* m, unsigned long pid) {
+	if (m->pid == NULL_PID) {
+		m->pid = pid;
+		return 0;
+	}
+	return 1;
+}
+
+// Eventually, there will need to be a hook into the scheduling mechanism
+//  that checks the currently running process and check that against the
+//  mutex's pid lock
+unsigned char release_mutex(struct Mutex* m, unsigned long pid) {
+	if (m->pid == pid) {
+		m->pid = NULL_PID;
+		return 0;
+	}
+	return 1;
+}
diff --git a/src/util/mutex.h b/src/util/mutex.h
new file mode 100644
index 0000000..8c9a097
--- /dev/null
+++ b/src/util/mutex.h
@@ -0,0 +1,15 @@
+#ifndef SYS_MUTEX_H
+#define SYS_MUTEX_H
+
+#define NULL_PID 0
+#define SCHED_PID 1
+
+struct Mutex {
+	unsigned long* addr;
+	unsigned long pid;
+};
+
+unsigned char lock_mutex(struct Mutex*, unsigned long);
+unsigned char release_mutex(struct Mutex*, unsigned long);
+
+#endif
-- 
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