From f0c5ac3c8222d4d89b8e2d2a726427a7ec64e538 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Wed, 10 Dec 2025 17:20:14 +0100
Subject: kstd: extract bitwise enum operations

---
 .clang-format                                      |  2 +
 .../include/x86_64/cpu/impl/control_registers.hpp  | 77 +++++-----------------
 .../x86_64/cpu/impl/model_specific_register.hpp    | 44 ++++---------
 arch/x86_64/include/x86_64/memory/page_table.hpp   | 31 ++++-----
 libs/kstd/CMakeLists.txt                           |  2 +
 libs/kstd/include/kstd/ext/bitfield_enum           | 64 ++++++++++++++++++
 6 files changed, 110 insertions(+), 110 deletions(-)
 create mode 100644 libs/kstd/include/kstd/ext/bitfield_enum

diff --git a/.clang-format b/.clang-format
index a47e396..e54cb03 100644
--- a/.clang-format
+++ b/.clang-format
@@ -61,6 +61,8 @@ IncludeCategories:
     Priority: 110
   - Regex: '"[[:alnum:]._\/]+\.hpp"'
     Priority: 300
+  - Regex: '<kstd/[[:alnum:]._\/]+>'
+    Priority: 400
   - Regex: '<[[:alnum:]._\/]+\.hpp>'
     Priority: 600
   - Regex: '<[[:alnum:]._]+(?!\.(h|hpp))>'
diff --git a/arch/x86_64/include/x86_64/cpu/impl/control_registers.hpp b/arch/x86_64/include/x86_64/cpu/impl/control_registers.hpp
index d892360..0c2254a 100644
--- a/arch/x86_64/include/x86_64/cpu/impl/control_registers.hpp
+++ b/arch/x86_64/include/x86_64/cpu/impl/control_registers.hpp
@@ -1,8 +1,12 @@
 #ifndef TEACHOS_X86_64_CPU_IMPL_CONTROL_REGISTERS_HPP
 #define TEACHOS_X86_64_CPU_IMPL_CONTROL_REGISTERS_HPP
 
+// IWYU pragma: private
+
 #include "kapi/memory/address.hpp"
 
+#include <kstd/ext/bitfield_enum>
+
 #include <cstdint>
 #include <string_view>
 #include <type_traits>
@@ -83,72 +87,12 @@ namespace teachos::cpu::x86_64
       paging = 1uz << 31
     };
 
-    constexpr auto operator|(cr0_flags lhs, cr0_flags rhs) -> cr0_flags
-    {
-      return static_cast<cr0_flags>(static_cast<std::underlying_type_t<cr0_flags>>(lhs) |
-                                    static_cast<std::underlying_type_t<cr0_flags>>(rhs));
-    }
-
-    constexpr auto operator|=(cr0_flags & lhs, cr0_flags rhs) -> cr0_flags &
-    {
-      lhs = lhs | rhs;
-      return lhs;
-    }
-
-    constexpr auto operator&(cr0_flags lhs, cr0_flags rhs) -> cr0_flags
-    {
-      return static_cast<cr0_flags>(static_cast<std::underlying_type_t<cr0_flags>>(lhs) &
-                                    static_cast<std::underlying_type_t<cr0_flags>>(rhs));
-    }
-
-    constexpr auto operator&=(cr0_flags & lhs, cr0_flags rhs) -> cr0_flags &
-    {
-      lhs = lhs & rhs;
-      return lhs;
-    }
-
-    constexpr auto operator~(cr0_flags lhs) -> cr0_flags
-    {
-      // NOLINTNEXTLINE(clang-analyzer-optin.core.EnumCastOutOfRange)
-      return static_cast<cr0_flags>(~static_cast<std::underlying_type_t<cr0_flags>>(lhs));
-    }
-
     enum struct cr3_flags : std::uint64_t
     {
       page_level_write_through = 1uz << 0,
       page_level_cache_disable = 1uz << 1,
     };
 
-    constexpr auto operator|(cr3_flags lhs, cr3_flags rhs) -> cr3_flags
-    {
-      return static_cast<cr3_flags>(static_cast<std::underlying_type_t<cr3_flags>>(lhs) |
-                                    static_cast<std::underlying_type_t<cr3_flags>>(rhs));
-    }
-
-    constexpr auto operator|=(cr3_flags & lhs, cr3_flags rhs) -> cr3_flags &
-    {
-      lhs = lhs | rhs;
-      return lhs;
-    }
-
-    constexpr auto operator&(cr3_flags lhs, cr3_flags rhs) -> cr3_flags
-    {
-      return static_cast<cr3_flags>(static_cast<std::underlying_type_t<cr3_flags>>(lhs) &
-                                    static_cast<std::underlying_type_t<cr3_flags>>(rhs));
-    }
-
-    constexpr auto operator&=(cr3_flags & lhs, cr3_flags rhs) -> cr3_flags &
-    {
-      lhs = lhs & rhs;
-      return lhs;
-    }
-
-    constexpr auto operator~(cr3_flags lhs) -> cr3_flags
-    {
-      // NOLINTNEXTLINE(clang-analyzer-optin.core.EnumCastOutOfRange)
-      return static_cast<cr3_flags>(~static_cast<std::underlying_type_t<cr3_flags>>(lhs));
-    }
-
     struct cr3_value
     {
       constexpr cr3_value() = default;
@@ -193,4 +137,17 @@ namespace teachos::cpu::x86_64
 
 }  // namespace teachos::cpu::x86_64
 
+namespace kstd::ext
+{
+  template<>
+  struct is_bitfield_enum<teachos::cpu::x86_64::impl::cr0_flags> : std::true_type
+  {
+  };
+
+  template<>
+  struct is_bitfield_enum<teachos::cpu::x86_64::impl::cr3_flags> : std::true_type
+  {
+  };
+}  // namespace kstd::ext
+
 #endif
\ No newline at end of file
diff --git a/arch/x86_64/include/x86_64/cpu/impl/model_specific_register.hpp b/arch/x86_64/include/x86_64/cpu/impl/model_specific_register.hpp
index 8a41a8a..ff2c8ad 100644
--- a/arch/x86_64/include/x86_64/cpu/impl/model_specific_register.hpp
+++ b/arch/x86_64/include/x86_64/cpu/impl/model_specific_register.hpp
@@ -1,6 +1,10 @@
 #ifndef TEACHOS_X86_64_CPU_IMPL_MODEL_SPECIFIC_REGISTER_HPP
 #define TEACHOS_X86_64_CPU_IMPL_MODEL_SPECIFIC_REGISTER_HPP
 
+// IWYU pragma: private
+
+#include <kstd/ext/bitfield_enum>
+
 #include <bit>
 #include <cstdint>
 #include <type_traits>
@@ -73,40 +77,20 @@ namespace teachos::cpu::x86_64
       execute_disable_bit_enable = 1uz << 11,
     };
 
-    constexpr auto operator|(ia32_efer_flags lhs, ia32_efer_flags rhs) -> ia32_efer_flags
-    {
-      return static_cast<ia32_efer_flags>(static_cast<std::underlying_type_t<ia32_efer_flags>>(lhs) |
-                                          static_cast<std::underlying_type_t<ia32_efer_flags>>(rhs));
-    }
-
-    constexpr auto operator|=(ia32_efer_flags & lhs, ia32_efer_flags rhs) -> ia32_efer_flags &
-    {
-      lhs = lhs | rhs;
-      return lhs;
-    }
-
-    constexpr auto operator&(ia32_efer_flags lhs, ia32_efer_flags rhs) -> ia32_efer_flags
-    {
-      return static_cast<ia32_efer_flags>(static_cast<std::underlying_type_t<ia32_efer_flags>>(lhs) &
-                                          static_cast<std::underlying_type_t<ia32_efer_flags>>(rhs));
-    }
-
-    constexpr auto operator&=(ia32_efer_flags & lhs, ia32_efer_flags rhs) -> ia32_efer_flags &
-    {
-      lhs = lhs & rhs;
-      return lhs;
-    }
-
-    constexpr auto operator~(ia32_efer_flags lhs) -> ia32_efer_flags
-    {
-      // NOLINTNEXTLINE(clang-analyzer-optin.core.EnumCastOutOfRange)
-      return static_cast<ia32_efer_flags>(~static_cast<std::underlying_type_t<ia32_efer_flags>>(lhs));
-    }
-
   }  // namespace impl
 
   using i32_efer = impl::model_specific_register<impl::ia32_efer_number, impl::ia32_efer_flags>;
 
 }  // namespace teachos::cpu::x86_64
 
+namespace kstd::ext
+{
+
+  template<>
+  struct is_bitfield_enum<teachos::cpu::x86_64::impl::ia32_efer_flags> : std::true_type
+  {
+  };
+
+}  // namespace kstd::ext
+
 #endif
\ No newline at end of file
diff --git a/arch/x86_64/include/x86_64/memory/page_table.hpp b/arch/x86_64/include/x86_64/memory/page_table.hpp
index ce34e23..22616e8 100644
--- a/arch/x86_64/include/x86_64/memory/page_table.hpp
+++ b/arch/x86_64/include/x86_64/memory/page_table.hpp
@@ -3,11 +3,14 @@
 
 #include "kapi/memory.hpp"
 
+#include <kstd/ext/bitfield_enum>
+
 #include <array>
 #include <bit>
 #include <cstddef>
 #include <cstdint>
 #include <optional>
+#include <type_traits>
 #include <utility>
 
 namespace teachos::memory::x86_64
@@ -87,26 +90,6 @@ namespace teachos::memory::x86_64
     std::array<entry, entry_count> m_entries{};
   };
 
-  constexpr auto operator|(page_table::entry::flags lhs, page_table::entry::flags rhs) -> page_table::entry::flags
-  {
-    return std::bit_cast<page_table::entry::flags>(std::to_underlying(lhs) | std::to_underlying(rhs));
-  }
-
-  constexpr auto operator|=(page_table::entry::flags & lhs, page_table::entry::flags rhs) -> page_table::entry::flags &
-  {
-    return lhs = lhs | rhs;
-  }
-
-  constexpr auto operator&(page_table::entry::flags lhs, page_table::entry::flags rhs) -> page_table::entry::flags
-  {
-    return std::bit_cast<page_table::entry::flags>(std::to_underlying(lhs) & std::to_underlying(rhs));
-  }
-
-  constexpr auto operator~(page_table::entry::flags flags)
-  {
-    return std::bit_cast<page_table::entry::flags>(~std::to_underlying(flags));
-  }
-
   //! A recursively mapped page table.
   template<std::size_t Level>
     requires(Level > 0uz && Level < 5uz)
@@ -155,4 +138,12 @@ namespace teachos::memory::x86_64
 
 }  // namespace teachos::memory::x86_64
 
+namespace kstd::ext
+{
+  template<>
+  struct is_bitfield_enum<teachos::memory::x86_64::page_table::entry::flags> : std::true_type
+  {
+  };
+}  // namespace kstd::ext
+
 #endif
\ No newline at end of file
diff --git a/libs/kstd/CMakeLists.txt b/libs/kstd/CMakeLists.txt
index e0c551c..d83e704 100644
--- a/libs/kstd/CMakeLists.txt
+++ b/libs/kstd/CMakeLists.txt
@@ -22,6 +22,8 @@ target_sources("kstd" PUBLIC
     "include/kstd/bits/shared_ptr.hpp"
     "include/kstd/bits/unique_ptr.hpp"
 
+    "include/kstd/ext/bitfield_enum"
+
     "include/kstd/asm_ptr"
     "include/kstd/memory"
     "include/kstd/mutex"
diff --git a/libs/kstd/include/kstd/ext/bitfield_enum b/libs/kstd/include/kstd/ext/bitfield_enum
new file mode 100644
index 0000000..327af45
--- /dev/null
+++ b/libs/kstd/include/kstd/ext/bitfield_enum
@@ -0,0 +1,64 @@
+#ifndef KSTD_EXT_BITFIELD_ENUM_HPP
+#define KSTD_EXT_BITFIELD_ENUM_HPP
+
+#include <bit>
+#include <type_traits>
+#include <utility>
+
+namespace kstd::ext
+{
+
+  template<typename EnumType>
+    requires std::is_enum_v<EnumType>
+  struct is_bitfield_enum : std::false_type
+  {
+  };
+
+  template<typename EnumType>
+  concept bitfield_enum = is_bitfield_enum<EnumType>::value;
+
+};  // namespace kstd::ext
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator|(EnumType lhs, EnumType rhs) -> EnumType
+{
+  return std::bit_cast<EnumType>(std::to_underlying(lhs) | std::to_underlying(rhs));
+}
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator|=(EnumType & lhs, EnumType rhs) -> EnumType &
+{
+  return lhs = lhs | rhs;
+}
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator&(EnumType lhs, EnumType rhs) -> EnumType
+{
+  return std::bit_cast<EnumType>(std::to_underlying(lhs) & std::to_underlying(rhs));
+}
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator&=(EnumType & lhs, EnumType rhs) -> EnumType &
+{
+  return lhs = lhs & rhs;
+}
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator^(EnumType lhs, EnumType rhs) -> EnumType
+{
+  return std::bit_cast<EnumType>(std::to_underlying(lhs) ^ std::to_underlying(rhs));
+}
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator^=(EnumType & lhs, EnumType rhs) -> EnumType &
+{
+  return lhs = lhs ^ rhs;
+}
+
+template<kstd::ext::bitfield_enum EnumType>
+constexpr auto operator~(EnumType lhs) -> EnumType
+{
+  return std::bit_cast<EnumType>(~std::to_underlying(lhs));
+}
+
+#endif
\ No newline at end of file
-- 
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