common: Add basic bit manipulation utility function to Common

1 files changed, 61 insertions, 0 deletions

diff --git a/src/common/bit_util.h b/src/common/bit_util.h
new file mode 100644
index 000000000..1eea17ba1
--- /dev/null
+++ b/src/common/bit_util.h
@@ -0,0 +1,61 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <climits>
+#include <cstddef>
+
+#ifdef _MSC_VER
+#include <intrin.h>
+#endif
+
+#include "common/common_types.h"
+
+namespace Common {
+
+/// Gets the size of a specified type T in bits.
+template <typename T>
+constexpr std::size_t BitSize() {
+    return sizeof(T) * CHAR_BIT;
+}
+
+#ifdef _MSC_VER
+inline u32 CountLeadingZeroes32(u32 value) {
+    unsigned long leading_zero = 0;
+
+    if (_BitScanReverse(&leading_zero, value) != 0) {
+        return 31 - leading_zero;
+    }
+
+    return 32;
+}
+
+inline u64 CountLeadingZeroes64(u64 value) {
+    unsigned long leading_zero = 0;
+
+    if (_BitScanReverse64(&leading_zero, value) != 0) {
+        return 63 - leading_zero;
+    }
+
+    return 64;
+}
+#else
+inline u32 CountLeadingZeroes32(u32 value) {
+    if (value == 0) {
+        return 32;
+    }
+
+    return __builtin_clz(value);
+}
+
+inline u64 CountLeadingZeroes64(u64 value) {
+    if (value == 0) {
+        return 64;
+    }
+
+    return __builtin_clzll(value);
+}
+#endif
+} // namespace Common