First Commit

common/BitUtils.h

@@ -0,0 +1,100 @@
+// SPDX-FileCopyrightText: 2002-2025 PCSX2 Dev Team
+// SPDX-License-Identifier: GPL-3.0+
+
+#pragma once
+
+#include "common/Pcsx2Defs.h"
+
+#include <bit>
+#include <cstring>
+
+#ifdef _MSC_VER
+
+#include <intrin.h>
+
+#else
+
+static inline int _BitScanReverse(unsigned long* const Index, const unsigned long Mask)
+{
+	if (Mask == 0)
+		return 0;
+
+	// For some reason, clang won't emit bsr if we use std::countl_zeros()...
+	*Index = 31 - __builtin_clz(Mask);
+	return 1;
+}
+
+#endif
+
+namespace Common
+{
+	template <typename T>
+	static constexpr __fi bool IsAligned(T value, unsigned int alignment)
+	{
+		return (value % static_cast<T>(alignment)) == 0;
+	}
+
+	template <typename T>
+	static constexpr __fi T AlignUp(T value, unsigned int alignment)
+	{
+		return (value + static_cast<T>(alignment - 1)) / static_cast<T>(alignment) * static_cast<T>(alignment);
+	}
+
+	template <typename T>
+	static constexpr __fi T AlignDown(T value, unsigned int alignment)
+	{
+		return value / static_cast<T>(alignment) * static_cast<T>(alignment);
+	}
+
+	template <typename T>
+	static constexpr __fi bool IsAlignedPow2(T value, unsigned int alignment)
+	{
+		return (value & static_cast<T>(alignment - 1)) == 0;
+	}
+
+	template <typename T>
+	static constexpr __fi T AlignUpPow2(T value, unsigned int alignment)
+	{
+		return (value + static_cast<T>(alignment - 1)) & static_cast<T>(~static_cast<T>(alignment - 1));
+	}
+
+	template <typename T>
+	static constexpr __fi T AlignDownPow2(T value, unsigned int alignment)
+	{
+		return value & static_cast<T>(~static_cast<T>(alignment - 1));
+	}
+
+	template <typename T>
+	static constexpr T PageAlign(T size)
+	{
+		static_assert(std::has_single_bit(__pagesize), "Page size is a power of 2");
+		return Common::AlignUpPow2(size, __pagesize);
+	}
+
+	__fi static u32 CountLeadingSignBits(s32 n)
+	{
+		// If the sign bit is 1, we invert the bits to 0 for count-leading-zero.
+		if (n < 0)
+			n = ~n;
+
+		// If BSR is used directly, it would have an undefined value for 0.
+		if (n == 0)
+			return 32;
+
+		// Perform our count leading zero.
+		return std::countl_zero(static_cast<u32>(n));
+	}
+} // namespace Common
+
+template <typename T>
+[[maybe_unused]] __fi static T GetBufferT(const u8* buffer, u32 offset)
+{
+	T value;
+	std::memcpy(&value, buffer + offset, sizeof(value));
+	return value;
+}
+
+[[maybe_unused]] __fi static u8 GetBufferU8(const u8* buffer, u32 offset) { return GetBufferT<u8>(buffer, offset); }
+[[maybe_unused]] __fi static u16 GetBufferU16(const u8* buffer, u32 offset) { return GetBufferT<u16>(buffer, offset); }
+[[maybe_unused]] __fi static u32 GetBufferU32(const u8* buffer, u32 offset) { return GetBufferT<u32>(buffer, offset); }
+[[maybe_unused]] __fi static u64 GetBufferU64(const u8* buffer, u32 offset) { return GetBufferT<u64>(buffer, offset); }