FEXCore: Moves BitUtils to FHU

No functional change

FEXHeaderUtils/FEXHeaderUtils/BitUtils.h

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: MIT
+#pragma once
+
+// Header for various utilities that operate on bits and bytes.
+
+#include <bit>
+#include <climits>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
+#include <type_traits>
+
+namespace FEXCore {
+
+// Determines the number of bits inside of a given type.
+template <typename T>
+[[nodiscard]] constexpr size_t BitSize() noexcept {
+    return sizeof(T) * CHAR_BIT;
+}
+
+// Swaps the bytes of a 16-bit unsigned value.
+[[nodiscard]] inline uint16_t BSwap16(uint16_t value) noexcept {
+#ifdef __GNUC__
+    return __builtin_bswap16(value);
+#else
+    return (value >> 8) | (value << 8);
+#endif
+}
+
+// Swaps the bytes of a 32-bit unsigned value.
+[[nodiscard]] inline uint32_t BSwap32(uint32_t value) noexcept {
+#ifdef __GNUC__
+    return __builtin_bswap32(value);
+#else
+    return ((value & 0xFF000000U) >> 24) | ((value & 0x00FF0000U) >> 8) |
+           ((value & 0x0000FF00U) << 8) | ((value & 0x000000FFU) << 24);
+#endif
+}
+
+// Swaps the bytes of a 64-bit unsigned value.
+[[nodiscard]] inline uint64_t BSwap64(uint64_t value) noexcept {
+#ifdef __GNUC__
+    return __builtin_bswap64(value);
+#else
+    return ((value & 0xFF00000000000000ULL) >> 56) | ((value & 0x00FF000000000000ULL) >> 40) |
+           ((value & 0x0000FF0000000000ULL) >> 24) | ((value & 0x000000FF00000000ULL) >> 8) |
+           ((value & 0x00000000FF000000ULL) << 8) | ((value & 0x0000000000FF0000ULL) << 24) |
+           ((value & 0x000000000000FF00ULL) << 40) | ((value & 0x00000000000000FFULL) << 56);
+#endif
+}
+
+// Finds the first least-significant set bit within a given value.
+// Note that all returned indices are 1-based, not 0-based.
+template <typename T>
+[[nodiscard]] constexpr int FindFirstSetBit(T value) noexcept {
+    static_assert(std::is_unsigned_v<T>, "Type must be unsigned.");
+
+    if (value == 0) {
+        return 0;
+    }
+
+    const int trailing_zeroes = std::countr_zero(value);
+    return trailing_zeroes + 1;
+}
+
+// Stand-in for std::bit_cast until libc++ implements it.
+template <typename To, typename From>
+[[nodiscard]] inline To BitCast(const From& source) noexcept
+{
+  static_assert(sizeof(From) == sizeof(To),
+                "BitCast source and destination types must be equal in size.");
+  static_assert(std::is_trivially_copyable_v<From>,
+                "BitCast source type must be trivially copyable.");
+  static_assert(std::is_trivially_copyable_v<To>,
+                "BitCast destination type must be trivially copyable.");
+
+  std::aligned_storage_t<sizeof(To), alignof(To)> storage;
+  std::memcpy(&storage, &source, sizeof(storage));
+  return reinterpret_cast<To&>(storage);
+}
+
+} // namespace FEXCore