From d9194d46ef70e7c9f76b876b2439c24649d57d1e Mon Sep 17 00:00:00 2001
From: Aleksa Vuckovic <aleksav013@gmail.com>
Date: Sat, 28 Jan 2023 21:06:31 +0100
Subject: atomic test_and_set; spinlocks

---
 kernel/Makefile               |  1 +
 kernel/include/atomic.h       | 17 +++++++++++++++++
 kernel/src/apic/rsdp.c        |  1 -
 kernel/src/main.c             |  1 +
 kernel/src/scheduler/atomic.c | 27 +++++++++++++++++++++++++++
 5 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 kernel/include/atomic.h
 create mode 100644 kernel/src/scheduler/atomic.c

(limited to 'kernel')

diff --git a/kernel/Makefile b/kernel/Makefile
index 9417ffd..93cfa24 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -33,6 +33,7 @@ OBJS = \
 	src/mem/paging.o \
 	src/misc/graphics.o \
 	src/misc/stdbuff.o \
+	src/scheduler/atomic.o \
 	src/scheduler/scheduler.o \
 	src/sys/syscall_asm.o \
 	src/sys/syscall.o \
diff --git a/kernel/include/atomic.h b/kernel/include/atomic.h
new file mode 100644
index 0000000..5ddc620
--- /dev/null
+++ b/kernel/include/atomic.h
@@ -0,0 +1,17 @@
+#ifndef ATOMIC
+#define ATOMIC
+
+#include <types.h>
+
+struct mutex_t {
+	volatile uint64_t* addr;
+};
+typedef struct mutex_t mutex_t;
+
+
+void init_mutex(mutex_t* mutex);
+bool test_and_set(mutex_t mutex, bool value);
+void lock(mutex_t mutex);
+void unlock(mutex_t mutex);
+
+#endif
diff --git a/kernel/src/apic/rsdp.c b/kernel/src/apic/rsdp.c
index 983ab5f..e0127aa 100644
--- a/kernel/src/apic/rsdp.c
+++ b/kernel/src/apic/rsdp.c
@@ -59,7 +59,6 @@ void list_sys_tables(void)
 	printf("\n");
 
 	kfree(rsdt);
-
 }
 
 uint64_t* find_sys_table_addr(const char* signature)
diff --git a/kernel/src/main.c b/kernel/src/main.c
index a14d5ad..766d69c 100644
--- a/kernel/src/main.c
+++ b/kernel/src/main.c
@@ -19,6 +19,7 @@
 #include <serial.h>
 #include <containter_of.h>
 #include <madt.h>
+#include <atomic.h>
 
 int kernel_main(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic);
 int kernel_main(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic)
diff --git a/kernel/src/scheduler/atomic.c b/kernel/src/scheduler/atomic.c
new file mode 100644
index 0000000..41ce3b9
--- /dev/null
+++ b/kernel/src/scheduler/atomic.c
@@ -0,0 +1,27 @@
+#include <types.h>
+#include <atomic.h>
+#include <libk/stdio.h>
+#include <heap.h>
+
+void init_mutex(mutex_t* mutex)
+{
+	mutex->addr = (uint64_t*)kalloc(sizeof(uint64_t));
+	*(mutex->addr) = 0;
+}
+
+bool test_and_set(mutex_t mutex, bool value)
+{
+	bool rax;
+	__asm__ volatile ("lock xchg %%rax, (%%rbx);" : "=a"(rax) : "b"(mutex.addr), "a"(value));
+	return rax;
+}
+
+void lock(mutex_t mutex)
+{
+	while (test_and_set(mutex, 1)) ;
+}
+
+void unlock(mutex_t mutex)
+{
+	test_and_set(mutex, 0);
+}
-- 
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