From 0924065511087d9ef3cf84183029ce8e834ff84a Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Sun, 19 Dec 2021 21:06:09 -0800
Subject: Configured atomic swap

---
 src/cpu/atomic/swap.a.h |  9 +++++++--
 src/cpu/irq.c           | 17 +++++++++++++++++
 src/sys/timer.c         |  2 +-
 src/sys/timer.h         |  2 +-
 src/util/mutex.c        |  7 +++++--
 5 files changed, 31 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/cpu/atomic/swap.a.h b/src/cpu/atomic/swap.a.h
index 63dd50b..1ca2a52 100644
--- a/src/cpu/atomic/swap.a.h
+++ b/src/cpu/atomic/swap.a.h
@@ -1,7 +1,12 @@
+#include "../../util/mutex.h"
+
 #ifndef CPU_ATOMIC_SWAP_A_H
 #define CPU_ATOMIC_SWAP_A_H
 
 /// https://stackoverflow.com/questions/16329123/use-of-strexeq-instead-of-strex-for-spinlock-implementation-in-arm
+/// https://elixir.bootlin.com/linux/v4.9/source/arch/arm/include/asm/spinlock.h
+/// https://elixir.bootlin.com/linux/v4.9/source/arch/arm/include/asm/spinlock_types.h#L23
+/// https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/3_Processes.html
 
 static inline void atm_lock(unsigned long pid, unsigned long* addr) {
 	unsigned long tmp, current_lock_value;
@@ -18,8 +23,8 @@ static inline void atm_lock(unsigned long pid, unsigned long* addr) {
 	: "cc");
 }
 
-static inline void atm_unlock(unsigned long* addr) {
-	unsigned long cleared = 0;
+static inline void atm_release(unsigned long* addr) {
+	unsigned long cleared = NULL_PID;
 	asm volatile(
 "	dmb\n"
 "	str %0, [%1]\n"
diff --git a/src/cpu/irq.c b/src/cpu/irq.c
index 0a1e080..adba7a7 100644
--- a/src/cpu/irq.c
+++ b/src/cpu/irq.c
@@ -3,6 +3,7 @@
 #include "../sys/timer.h"
 #include "../drivers/uart.a.h"
 #include "../drivers/uart.h"
+#include "../util/mutex.h"
 #include "../util/time.h"
 
 extern unsigned long cmdidx;
@@ -42,12 +43,14 @@ void c_irq_handler(void) {
 				} else {
 					unsigned long off = cmdidx;
 					if (off < 2048) {
+						// Newline Case
 						if (data == 0x0D) {
 							off = 0;
 							cmd[0] = 0x0;
 							//uart_char(0x0a);
 							uart_char(data);
 							uart_string("\033[?25l> \033[0K\033[?25h");
+						// Backspace Case
 						} else if (data == 0x08 || data == 0x7F) {
 							if (off > 0) {
 								off -= 1;
@@ -56,6 +59,19 @@ void c_irq_handler(void) {
 							uart_char((unsigned char)data);
 							uart_char(0x20);
 							uart_char((unsigned char)data);
+						// Lock Case
+						} else if (data == 0x6C) {
+							uart_char((unsigned char)data);
+							cmd[off] = (char) data;
+							off += 1;
+							lock_mutex(&exe_cnt_m, SCHED_PID);
+						// Release Case
+						} else if (data == 0x72) {
+							uart_char((unsigned char)data);
+							cmd[off] = (char) data;
+							off += 1;
+							release_mutex(&exe_cnt_m, SCHED_PID);
+						// Else output
 						} else {
 							uart_char((unsigned char)data);
 							cmd[off] = (char) data;
@@ -95,6 +111,7 @@ void c_irq_handler(void) {
 		c_timer();
 		//enable_irq();
 		enableirq();
+		return;
 	}
 	return;
 }
diff --git a/src/sys/timer.c b/src/sys/timer.c
index f4013d4..9df7b33 100644
--- a/src/sys/timer.c
+++ b/src/sys/timer.c
@@ -5,7 +5,7 @@
 #include "../drivers/uart.a.h"
 #include "../drivers/uart.h"
 
-#define TIMER_C
+#define SYS_TIMER_C
 extern char* os_info_v;
 
 unsigned long exe_cnt = 0;
diff --git a/src/sys/timer.h b/src/sys/timer.h
index 4774ed4..76fc015 100644
--- a/src/sys/timer.h
+++ b/src/sys/timer.h
@@ -1,7 +1,7 @@
 #ifndef SYS_TIMER_H
 #define SYS_TIMER_H
 
-#ifndef TIMER_C
+#ifndef SYS_TIMER_C
 extern struct Mutex exe_cnt_m;
 #endif
 
diff --git a/src/util/mutex.c b/src/util/mutex.c
index 86ffcf5..98dc849 100644
--- a/src/util/mutex.c
+++ b/src/util/mutex.c
@@ -1,8 +1,10 @@
 #include "../util/mutex.h"
+#include "../cpu/atomic/swap.a.h"
 
 unsigned char lock_mutex(struct Mutex* m, unsigned long pid) {
 	if (m->pid == NULL_PID) {
-		m->pid = pid;
+		//m->pid = pid;
+		atm_lock(pid, &m->pid);
 		return 0;
 	}
 	return 1;
@@ -13,7 +15,8 @@ unsigned char lock_mutex(struct Mutex* m, unsigned long pid) {
 //  mutex's pid lock
 unsigned char release_mutex(struct Mutex* m, unsigned long pid) {
 	if (m->pid == pid) {
-		m->pid = NULL_PID;
+		//m->pid = NULL_PID;
+		atm_release(&m->pid);
 		return 0;
 	}
 	return 1;
-- 
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