u128: Implement u128

For when we need a 128-bit integer

src/CMakeLists.txt

@@ -31,6 +31,8 @@ add_library(dynarmic
     common/sm4.cpp
     common/sm4.h
     common/string_util.h
+    common/u128.cpp
+    common/u128.h
     common/variant_util.h
     frontend/A32/decoder/arm.h
     frontend/A32/decoder/thumb16.h

src/common/u128.cpp

@@ -0,0 +1,64 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2018 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#include <array>
+
+#include "common/common_types.h"
+#include "common/u128.h"
+
+namespace Dynarmic {
+
+u128 operator<<(u128 operand, int amount) {
+    if (amount < 0) {
+        return operand >> -amount;
+    }
+
+    if (amount == 0) {
+        return operand;
+    }
+
+    if (amount < 64) {
+        u128 result;
+        result.lower = (operand.lower << amount);
+        result.upper = (operand.upper << amount) | (operand.lower >> (64 - amount));
+        return result;
+    }
+
+    if (amount < 128) {
+        u128 result;
+        result.upper = operand.lower << (amount - 64);
+        return result;
+    }
+
+    return {};
+}
+
+u128 operator>>(u128 operand, int amount) {
+    if (amount < 0) {
+        return operand << -amount;
+    }
+
+    if (amount == 0) {
+        return operand;
+    }
+
+    if (amount < 64) {
+        u128 result;
+        result.lower = (operand.lower >> amount) | (operand.upper << (64 - amount));
+        result.upper = (operand.upper >> amount);
+        return result;
+    }
+
+    if (amount < 128) {
+        u128 result;
+        result.lower = operand.upper >> (amount - 64);
+        return result;
+    }
+
+    return {};
+}
+
+} // namespace Dynarmic

src/common/u128.h

@@ -0,0 +1,57 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2018 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#pragma once
+
+#include <cstring>
+#include <type_traits>
+
+#include "common/bit_util.h"
+#include "common/common_types.h"
+
+namespace Dynarmic {
+
+struct u128 {
+    u128() = default;
+    u128(const u128&) = default;
+    u128(u128&&) = default;
+    u128& operator=(const u128&) = default;
+    u128& operator=(u128&&) = default;
+
+    u128(u64 lower_, u64 upper_) : lower(lower_), upper(upper_) {}
+
+    template <typename T>
+    /* implicit */ u128(T value) : lower(value), upper(0) {
+        static_assert(std::is_integral_v<T>);
+        static_assert(Common::BitSize<T>() <= Common::BitSize<u64>());
+    }
+
+    u64 lower = 0;
+    u64 upper = 0;
+};
+
+static_assert(Common::BitSize<u128>() == 128);
+static_assert(std::is_standard_layout_v<u128>);
+static_assert(std::is_trivially_copyable_v<u128>);
+
+inline u128 operator+(u128 a, u128 b) {
+    u128 result;
+    result.lower = a.lower + b.lower;
+    result.upper = a.upper + b.upper + (a.lower > result.lower);
+    return result;
+}
+
+inline u128 operator-(u128 a, u128 b) {
+    u128 result;
+    result.lower = a.lower - b.lower;
+    result.upper = a.upper - b.upper - (a.lower < result.lower);
+    return result;
+}
+
+u128 operator<<(u128 operand, int amount);
+u128 operator>>(u128 operand, int amount);
+
+} // namespace Dynarmic