From 845a96f5e6bfbbbeba19bf3df07f0e9de53d9a88 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Wed, 29 Oct 2025 11:40:49 +0100
Subject: kapi: export frame_allocator interface

---
 .../x86_64/include/x86_64/memory/region_allocator.hpp |  7 ++++---
 arch/x86_64/src/kapi/memory.cpp                       | 12 ++++++++++++
 arch/x86_64/src/memory/region_allocator.cpp           |  6 +++---
 kapi/include/kapi/memory.hpp                          |  6 ++++--
 kapi/include/kapi/memory/frame_allocator.hpp          | 19 +++++++++++++++++++
 5 files changed, 42 insertions(+), 8 deletions(-)
 create mode 100644 kapi/include/kapi/memory/frame_allocator.hpp

diff --git a/arch/x86_64/include/x86_64/memory/region_allocator.hpp b/arch/x86_64/include/x86_64/memory/region_allocator.hpp
index a918195..913b0bb 100644
--- a/arch/x86_64/include/x86_64/memory/region_allocator.hpp
+++ b/arch/x86_64/include/x86_64/memory/region_allocator.hpp
@@ -3,6 +3,7 @@
 
 #include "kapi/memory/address.hpp"
 #include "kapi/memory/frame.hpp"
+#include "kapi/memory/frame_allocator.hpp"
 
 #include <multiboot2/information.hpp>
 
@@ -15,7 +16,7 @@ namespace teachos::memory::x86_64
    * @brief Allocates memory linearly using memory areas read from the multiboot2 information pointer and leaks any
    * deallocated frames.
    */
-  struct region_allocator
+  struct region_allocator final : frame_allocator
   {
     struct memory_information
     {
@@ -43,7 +44,7 @@ namespace teachos::memory::x86_64
      *
      * @return next free physical frame or nullopt if none was found.
      */
-    auto allocate_frame() -> std::optional<frame>;
+    auto allocate() -> std::optional<frame> override;
 
     /**
      * @brief Deallocates a previously allocated physical frame.
@@ -54,7 +55,7 @@ namespace teachos::memory::x86_64
      *
      * @param physical_frame Previously allocated physical_frame that should be deallocated.
      */
-    auto deallocate_frame(frame const & physical_frame) -> void;
+    auto release(frame frame) -> void override;
 
   private:
     /**
diff --git a/arch/x86_64/src/kapi/memory.cpp b/arch/x86_64/src/kapi/memory.cpp
index 55e6ba9..be47941 100644
--- a/arch/x86_64/src/kapi/memory.cpp
+++ b/arch/x86_64/src/kapi/memory.cpp
@@ -1,6 +1,7 @@
 #include "kapi/memory.hpp"
 
 #include "kapi/memory/frame.hpp"
+#include "kapi/memory/frame_allocator.hpp"
 #include "kapi/system.hpp"
 
 #include "x86_64/boot/boot.hpp"
@@ -21,6 +22,7 @@ namespace teachos::memory
   namespace
   {
     auto constinit is_initialized = std::atomic_flag{};
+    auto constinit allocator = static_cast<frame_allocator *>(nullptr);
 
     auto create_memory_information() -> region_allocator::memory_information
     {
@@ -34,6 +36,16 @@ namespace teachos::memory
     };
   }  // namespace
 
+  auto active_allocator() -> frame_allocator &
+  {
+    if (!allocator)
+    {
+      system::panic("[x86_64] The frame allocator has not been set yet.");
+    }
+
+    return *allocator;
+  }
+
   auto init() -> void
   {
     if (is_initialized.test_and_set())
diff --git a/arch/x86_64/src/memory/region_allocator.cpp b/arch/x86_64/src/memory/region_allocator.cpp
index 91a5d49..11ffce2 100644
--- a/arch/x86_64/src/memory/region_allocator.cpp
+++ b/arch/x86_64/src/memory/region_allocator.cpp
@@ -51,7 +51,7 @@ namespace teachos::memory::x86_64
     }
   }
 
-  auto region_allocator::allocate_frame() -> std::optional<frame>
+  auto region_allocator::allocate() -> std::optional<frame>
   {
     if (!m_current_region)
     {
@@ -80,8 +80,8 @@ namespace teachos::memory::x86_64
       return allocated;
     }
 
-    return allocate_frame();
+    return allocate();
   }
 
-  auto region_allocator::deallocate_frame(frame const &) -> void {}
+  auto region_allocator::release(frame) -> void {}
 }  // namespace teachos::memory::x86_64
diff --git a/kapi/include/kapi/memory.hpp b/kapi/include/kapi/memory.hpp
index 3ad5ac5..3daaa86 100644
--- a/kapi/include/kapi/memory.hpp
+++ b/kapi/include/kapi/memory.hpp
@@ -1,11 +1,13 @@
 #ifndef TEACHOS_KAPI_MEMORY_HPP
 #define TEACHOS_KAPI_MEMORY_HPP
 
-#include "kapi/memory/address.hpp"  // IWYU pragma: export
-#include "kapi/memory/frame.hpp"    // IWYU pragma: export
+#include "kapi/memory/address.hpp"          // IWYU pragma: export
+#include "kapi/memory/frame.hpp"            // IWYU pragma: export
+#include "kapi/memory/frame_allocator.hpp"  // IWYU pragma: export
 
 namespace teachos::memory
 {
+  auto active_allocator() -> frame_allocator &;
   auto init() -> void;
 }  // namespace teachos::memory
 
diff --git a/kapi/include/kapi/memory/frame_allocator.hpp b/kapi/include/kapi/memory/frame_allocator.hpp
new file mode 100644
index 0000000..f9393ee
--- /dev/null
+++ b/kapi/include/kapi/memory/frame_allocator.hpp
@@ -0,0 +1,19 @@
+#ifndef TEACHOS_KAPI_MEMORY_FRAME_ALLOCATOR_HPP
+#define TEACHOS_KAPI_MEMORY_FRAME_ALLOCATOR_HPP
+
+#include "kapi/memory/frame.hpp"
+
+#include <optional>
+
+namespace teachos::memory
+{
+
+  struct frame_allocator
+  {
+    virtual auto allocate() -> std::optional<frame> = 0;
+    virtual auto release(frame frame) -> void = 0;
+  };
+
+}  // namespace teachos::memory
+
+#endif  // TEACHOS_KAPI_MEMORY_FRAME_ALLOCATOR_HPP
\ No newline at end of file
-- 
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