kapi/memory: implement multi-frame allocation

1 files changed, 25 insertions, 8 deletions

diff --git a/arch/x86_64/src/memory/region_allocator.cpp b/arch/x86_64/src/memory/region_allocator.cpp
index efa1f4a..7a8fb8b 100644
--- a/arch/x86_64/src/memory/region_allocator.cpp
+++ b/arch/x86_64/src/memory/region_allocator.cpp
@@ -6,6 +6,7 @@
 #include <multiboot2/information.hpp>
 
 #include <algorithm>
+#include <cstddef>
 #include <optional>
 #include <ranges>
 #include <utility>
@@ -56,7 +57,7 @@ namespace teachos::memory::x86_64
 
     m_current_region = *lowest_region;
     if (auto start_of_region = frame::containing(physical_address{m_current_region->base});
-        start_of_region < m_next_frame)
+        start_of_region > m_next_frame)
     {
       m_next_frame = start_of_region;
     }
@@ -96,16 +97,32 @@ namespace teachos::memory::x86_64
     return m_current_region.transform([this](auto) -> auto { return m_next_frame; });
   }
 
-  auto region_allocator::allocate() noexcept -> std::optional<frame>
+  auto region_allocator::allocate_many(std::size_t count) noexcept -> std::optional<std::pair<frame, std::size_t>>
   {
-    return find_next_frame().transform([this](auto frame) -> auto {
-      auto result = frame;
-      ++m_next_frame;
-      return result;
-    });
+    while (m_current_region)
+    {
+      auto result = find_next_frame();
+
+      if (result)
+      {
+        auto region_end = last_frame(*m_current_region);
+        if ((region_end.number() - result->number()) >= count)
+        {
+          m_next_frame = m_next_frame + count;
+          return std::make_pair(*result, count);
+        }
+        else
+        {
+          m_next_frame = region_end + 1;
+          choose_next_region();
+        }
+      }
+    }
+
+    return std::nullopt;
   }
 
-  auto region_allocator::release(frame) -> void {}
+  auto region_allocator::release_many(std::pair<frame, std::size_t>) -> void {}
 
   auto region_allocator::next_free_frame() noexcept -> std::optional<frame>
   {