Creating base frame allocation code

2 files changed, 48 insertions, 2 deletions

diff --git a/arch/x86_64/include/arch/kernel/main.hpp b/arch/x86_64/include/arch/kernel/main.hpp
index 6759eb2..8813b46 100644
--- a/arch/x86_64/include/arch/kernel/main.hpp
+++ b/arch/x86_64/include/arch/kernel/main.hpp
@@ -1,8 +1,6 @@
 #ifndef TEACHOS_ARCH_X86_64_KERNEL_MAIN_HPP
 #define TEACHOS_ARCH_X86_64_KERNEL_MAIN_HPP
 
-#include <cstddef>
-
 namespace teachos::arch::kernel
 {
   auto main() -> void;
diff --git a/arch/x86_64/include/arch/memory/frame_allocator.hpp b/arch/x86_64/include/arch/memory/frame_allocator.hpp
new file mode 100644
index 0000000..bcb0882
--- /dev/null
+++ b/arch/x86_64/include/arch/memory/frame_allocator.hpp
@@ -0,0 +1,48 @@
+#ifndef TEACHOS_ARCH_X86_64_MEMORY_FRAME_HPP
+#define TEACHOS_ARCH_X86_64_MEMORY_FRAME_HPP
+
+#include <cstddef>
+#include <optional>
+
+namespace teachos::arch::memory
+{
+  namespace
+  {
+    const size_t PAGE_FRAME_SIZE = 4096U;
+  }
+
+  struct Frame
+  {
+    size_t frame_number;
+
+    Frame(size_t frame_number)
+        : frame_number(frame_number)
+    {
+      // Nothing to do
+    }
+
+    auto containing_address(size_t address) -> Frame { return Frame{address / PAGE_FRAME_SIZE}; }
+  };
+
+  struct IFrameAllocator
+  {
+    virtual auto allocate_frame() -> std::optional<Frame> = 0;
+    virtual auto deallocate_frame(Frame frame) -> void = 0;
+  };
+
+  struct AreaFrameAllocator : public IFrameAllocator
+  {
+    Frame next_free_frame;
+    // std::optional<MemoryArea> current_area;
+    // MemoryArea * areas;
+    Frame kernel_start;
+    Frame kernel_end;
+    Frame multiboot_start;
+    Frame multiboot_end;
+
+    auto allocate_frame() -> std::optional<Frame> override;
+    auto deallocate_frame(Frame frame) -> void override;
+  };
+}  // namespace teachos::arch::memory
+
+#endif  // TEACHOS_ARCH_X86_64_MEMORY_FRAME_HPP