From 6da91da08e54d02a4087eaddcbe192bd53eeaa9f Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Mon, 8 Feb 2021 18:02:36 -0800
Subject: hle: kernel: Add KSpinLock implementation.

---
 src/core/CMakeLists.txt             |  2 ++
 src/core/hle/kernel/k_spin_lock.cpp | 54 +++++++++++++++++++++++++++++++++++++
 src/core/hle/kernel/k_spin_lock.h   | 33 +++++++++++++++++++++++
 3 files changed, 89 insertions(+)
 create mode 100644 src/core/hle/kernel/k_spin_lock.cpp
 create mode 100644 src/core/hle/kernel/k_spin_lock.h

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 8d4823f93..a6b5fef56 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -177,6 +177,8 @@ add_library(core STATIC
     hle/kernel/k_scoped_scheduler_lock_and_sleep.h
     hle/kernel/k_shared_memory.cpp
     hle/kernel/k_shared_memory.h
+    hle/kernel/k_spin_lock.cpp
+    hle/kernel/k_spin_lock.h
     hle/kernel/k_synchronization_object.cpp
     hle/kernel/k_synchronization_object.h
     hle/kernel/k_thread.cpp
diff --git a/src/core/hle/kernel/k_spin_lock.cpp b/src/core/hle/kernel/k_spin_lock.cpp
new file mode 100644
index 000000000..4412aa4bb
--- /dev/null
+++ b/src/core/hle/kernel/k_spin_lock.cpp
@@ -0,0 +1,54 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "core/hle/kernel/k_spin_lock.h"
+
+#if _MSC_VER
+#include <intrin.h>
+#if _M_AMD64
+#define __x86_64__ 1
+#endif
+#if _M_ARM64
+#define __aarch64__ 1
+#endif
+#else
+#if __x86_64__
+#include <xmmintrin.h>
+#endif
+#endif
+
+namespace {
+
+void ThreadPause() {
+#if __x86_64__
+    _mm_pause();
+#elif __aarch64__ && _MSC_VER
+    __yield();
+#elif __aarch64__
+    asm("yield");
+#endif
+}
+
+} // namespace
+
+namespace Kernel {
+
+void KSpinLock::Lock() {
+    while (lck.test_and_set(std::memory_order_acquire)) {
+        ThreadPause();
+    }
+}
+
+void KSpinLock::Unlock() {
+    lck.clear(std::memory_order_release);
+}
+
+bool KSpinLock::TryLock() {
+    if (lck.test_and_set(std::memory_order_acquire)) {
+        return false;
+    }
+    return true;
+}
+
+} // namespace Kernel
diff --git a/src/core/hle/kernel/k_spin_lock.h b/src/core/hle/kernel/k_spin_lock.h
new file mode 100644
index 000000000..12c4b2e88
--- /dev/null
+++ b/src/core/hle/kernel/k_spin_lock.h
@@ -0,0 +1,33 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <atomic>
+
+#include "core/hle/kernel/k_scoped_lock.h"
+
+namespace Kernel {
+
+class KSpinLock {
+public:
+    KSpinLock() = default;
+
+    KSpinLock(const KSpinLock&) = delete;
+    KSpinLock& operator=(const KSpinLock&) = delete;
+
+    KSpinLock(KSpinLock&&) = delete;
+    KSpinLock& operator=(KSpinLock&&) = delete;
+
+    void Lock();
+    void Unlock();
+    [[nodiscard]] bool TryLock();
+
+private:
+    std::atomic_flag lck = ATOMIC_FLAG_INIT;
+};
+
+using KScopedSpinLock = KScopedLock<KSpinLock>;
+
+} // namespace Kernel
-- 
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