From 14ed096fc5de6844cb116f3319c0d03043d26ea2 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Thu, 17 Jul 2025 21:09:02 +0000
Subject: x86-64: prepare new architecture

---
 .../x86_64/src/memory/allocator/physical_frame.cpp | 24 ------
 arch/x86_64/src/memory/region_allocator.cpp        | 95 ++++++++++++++++++++++
 2 files changed, 95 insertions(+), 24 deletions(-)
 delete mode 100644 arch/x86_64/src/memory/allocator/physical_frame.cpp
 create mode 100644 arch/x86_64/src/memory/region_allocator.cpp

(limited to 'arch/x86_64/src/memory')

diff --git a/arch/x86_64/src/memory/allocator/physical_frame.cpp b/arch/x86_64/src/memory/allocator/physical_frame.cpp
deleted file mode 100644
index ec387a1..0000000
--- a/arch/x86_64/src/memory/allocator/physical_frame.cpp
+++ /dev/null
@@ -1,24 +0,0 @@
-#include "arch/memory/allocator/physical_frame.hpp"
-
-namespace teachos::arch::memory::allocator
-{
-  auto physical_frame::containing_address(physical_address address) -> physical_frame
-  {
-    return physical_frame{address / PAGE_FRAME_SIZE};
-  }
-
-  auto physical_frame::start_address() const -> physical_address { return frame_number * PAGE_FRAME_SIZE; }
-
-  auto physical_frame::operator++(int) -> physical_frame
-  {
-    physical_frame const old_value = *this;
-    ++frame_number;
-    return old_value;
-  }
-
-  auto physical_frame::operator++() -> physical_frame &
-  {
-    ++frame_number;
-    return *this;
-  }
-}  // namespace teachos::arch::memory::allocator
diff --git a/arch/x86_64/src/memory/region_allocator.cpp b/arch/x86_64/src/memory/region_allocator.cpp
new file mode 100644
index 0000000..c9a98b4
--- /dev/null
+++ b/arch/x86_64/src/memory/region_allocator.cpp
@@ -0,0 +1,95 @@
+// #include "arch/memory/allocator/region_allocator.hpp"
+
+// #include "arch/exception_handling/assert.hpp"
+
+// #include <algorithm>
+// #include <array>
+// #include <ranges>
+
+#include "x86_64/memory/region_allocator.hpp"
+
+#include "x86_64/memory/address.hpp"
+#include "x86_64/memory/frame.hpp"
+
+#include <multiboot2/information.hpp>
+
+#include <algorithm>
+#include <ranges>
+
+namespace teachos::x86_64::memory
+{
+  namespace
+  {
+    auto constexpr last_frame(multiboot2::memory_map::region const & region)
+    {
+      return frame::containing(physical_address{region.base + region.size_in_B - 1});
+    }
+  }  // namespace
+
+  region_allocator::region_allocator(memory_information const & mem_info)
+      : m_next_frame{}
+      , m_current_region{}
+      , m_memory_map{}
+      , m_kernel_start(frame::containing(mem_info.image_range.first))
+      , m_kernel_end(frame::containing(mem_info.image_range.second))
+      , m_multiboot_start(frame::containing(mem_info.mbi_range.first))
+      , m_multiboot_end(frame::containing(mem_info.mbi_range.second))
+  {
+    choose_next_area();
+  }
+
+  auto region_allocator::choose_next_area() -> void
+  {
+    m_current_region.reset();
+    auto next_area_with_free_frames =
+        m_memory_map | std::views::filter(&multiboot2::memory_map::region::available) |
+        std::views::filter([next = m_next_frame](auto const & region) { return last_frame(region) >= next; });
+
+    auto lowest_region_with_free_frames =
+        std::ranges::min_element(next_area_with_free_frames, [](auto lhs, auto rhs) { return lhs.base < rhs.base; });
+
+    if (lowest_region_with_free_frames != next_area_with_free_frames.end())
+    {
+      m_current_region = *lowest_region_with_free_frames;
+      auto start_frame = frame::containing(physical_address{m_current_region->base});
+      if (m_next_frame < start_frame)
+      {
+        m_next_frame = start_frame;
+      }
+    }
+  }
+
+  auto region_allocator::allocate_frame() -> std::optional<frame>
+  {
+    if (!m_current_region)
+    {
+      return {};
+    }
+
+    auto const end_address = physical_address{m_current_region->base + m_current_region->size_in_B - 1};
+    auto end_frame = frame::containing(end_address);
+
+    if (m_next_frame > end_frame)
+    {
+      choose_next_area();
+    }
+    else if (m_next_frame >= m_kernel_start && m_next_frame <= m_kernel_end)
+    {
+      m_next_frame = m_kernel_end + 1;
+    }
+    else if (m_next_frame >= m_multiboot_start && m_next_frame <= m_multiboot_end)
+    {
+      m_next_frame = m_multiboot_end + 1;
+    }
+    else
+    {
+      auto allocated = m_next_frame;
+      ++m_next_frame;
+      return allocated;
+    }
+
+    return allocate_frame();
+  }
+
+  auto region_allocator::deallocate_frame(frame const &) -> void {}
+}  // namespace teachos::x86_64::memory
-- 
cgit v1.2.3