3 files changed, 82 insertions, 4 deletions

diff --git a/arch/x86_64/src/kapi/memory.cpp b/arch/x86_64/src/kapi/memory.cpp
index 3848fb8..99dcb5c 100644
--- a/arch/x86_64/src/kapi/memory.cpp
+++ b/arch/x86_64/src/kapi/memory.cpp
@@ -12,6 +12,7 @@
 #include <multiboot2/information.hpp>
 
 #include <atomic>
+#include <span>
 
 namespace teachos::memory
 {
@@ -25,11 +26,12 @@ namespace teachos::memory
     auto create_memory_information() -> x86_64::region_allocator::memory_information
     {
       auto const & mbi = boot::bootstrap_information.mbi;
+      auto mbi_span = std::span{std::bit_cast<std::byte *>(mbi), mbi->size_bytes()};
+      auto image_span = std::span{&boot::x86_64::_start_physical, &boot::x86_64::_end_physical};
 
-      return {.image_range = std::make_pair(physical_address{&boot::x86_64::_start_physical},
-                                            physical_address{&boot::x86_64::_end_physical}),
-              .mbi_range = std::make_pair(physical_address{std::bit_cast<std::byte *>(mbi)},
-                                          physical_address{std::bit_cast<std::byte *>(mbi) + mbi->size_bytes()}),
+      return {.image_range =
+                  std::make_pair(physical_address{&image_span.front()}, physical_address{&image_span.back()}),
+              .mbi_range = std::make_pair(physical_address{&mbi_span.front()}, physical_address{&mbi_span.back()}),
               .memory_map = mbi->memory_map()};
     };
 
diff --git a/arch/x86_64/src/memory/page_table.cpp b/arch/x86_64/src/memory/page_table.cpp
new file mode 100644
index 0000000..c716c5c
--- /dev/null
+++ b/arch/x86_64/src/memory/page_table.cpp
@@ -0,0 +1,57 @@
+#include "x86_64/memory/page_table.hpp"
+
+#include <algorithm>
+
+namespace teachos::memory::x86_64
+{
+
+  auto page_table::entry::clear() -> void
+  {
+    m_raw = 0;
+  }
+
+  auto page_table::entry::present() const -> bool
+  {
+    return (flags() & flags::present) != flags::empty;
+  }
+
+  auto page_table::entry::huge() const -> bool
+  {
+    return (flags() & flags::huge_page) != flags::empty;
+  }
+
+  auto page_table::entry::all_flags() const -> flags
+  {
+    return std::bit_cast<flags>(m_raw & ~frame_number_mask);
+  }
+
+  auto page_table::entry::frame() const -> std::optional<struct frame>
+  {
+    if (present())
+    {
+      return frame::containing(physical_address{m_raw & frame_number_mask});
+    }
+    return std::nullopt;
+  }
+
+  auto page_table::entry::frame(struct frame frame, flags flags) -> void
+  {
+    m_raw = (frame.start_address().raw() | static_cast<std::uint64_t>(flags));
+  };
+
+  auto page_table::operator[](std::size_t index) -> entry &
+  {
+    return m_entries.at(index);
+  }
+
+  auto page_table::operator[](std::size_t index) const -> entry const &
+  {
+    return m_entries.at(index);
+  }
+
+  auto page_table::clear() -> void
+  {
+    std::ranges::for_each(m_entries, &page_table::entry::clear);
+  }
+
+}  // namespace teachos::memory::x86_64
diff --git a/arch/x86_64/src/memory/paging_root.cpp b/arch/x86_64/src/memory/paging_root.cpp
new file mode 100644
index 0000000..1234308
--- /dev/null
+++ b/arch/x86_64/src/memory/paging_root.cpp
@@ -0,0 +1,19 @@
+#include "x86_64/memory/paging_root.hpp"
+
+#include <cstdint>
+
+namespace teachos::memory::x86_64
+{
+
+  namespace
+  {
+    constexpr auto PML_RECURSIVE_BASE = std::uintptr_t{0177777'776'776'776'776'0000uz};
+  }
+
+  auto paging_root::get() -> paging_root &
+  {
+    auto pml4_address = std::bit_cast<paging_root *>(PML_RECURSIVE_BASE);
+    return *pml4_address;
+  }
+
+}  // namespace teachos::memory::x86_64
\ No newline at end of file