3 files changed, 131 insertions, 0 deletions
diff --git a/kernel/include/kernel/memory.hpp b/kernel/include/kernel/memory.hpp
new file mode 100644
index 0000000..f09c519
--- /dev/null
+++ b/kernel/include/kernel/memory.hpp
@@ -0,0 +1,19 @@
+#ifndef TEACHOS_KERNEL_MEMORY_HPP
+#define TEACHOS_KERNEL_MEMORY_HPP
+
+#include "kapi/memory.hpp"
+
+#include "kernel/memory/heap_allocator.hpp"  // IWYU pragma: export
+
+namespace kernel::memory
+{
+
+  //! Get a handle to the global heap allocator.
+  auto get_heap_allocator() -> heap_allocator &;
+
+  //! Initialize the kernel heap.
+  auto init_heap(kapi::memory::linear_address base) -> void;
+
+}  // namespace kernel::memory
+
+#endif
+\ No newline at end of file
diff --git a/kernel/include/kernel/memory/free_list_allocator.hpp b/kernel/include/kernel/memory/free_list_allocator.hpp
new file mode 100644
index 0000000..53a7b61
--- /dev/null
+++ b/kernel/include/kernel/memory/free_list_allocator.hpp
@@ -0,0 +1,80 @@
+#ifndef TEACHOS_KERNEL_MEMORY_FREE_LIST_ALLOCATOR_HPP
+#define TEACHOS_KERNEL_MEMORY_FREE_LIST_ALLOCATOR_HPP
+
+#include "kapi/memory.hpp"
+
+#include "kernel/memory/heap_allocator.hpp"
+
+#include <kstd/mutex>
+
+#include <cstddef>
+#include <new>
+
+namespace kernel::memory
+{
+
+  //! A simple, dynamically sized heap allocator.
+  //!
+  //! This allocator is designed to perform first-fit allocation using an intrusive doubly-linked list. The heap is
+  //! expanded as needed.
+  struct free_list_allocator final : heap_allocator
+  {
+    //! Construct a new free list allocator with the given base address.
+    explicit free_list_allocator(kapi::memory::linear_address base) noexcept;
+
+    free_list_allocator(free_list_allocator const &) = delete;
+    free_list_allocator(free_list_allocator &&) = delete;
+    auto operator=(free_list_allocator const &) -> free_list_allocator & = delete;
+    auto operator=(free_list_allocator &&) -> free_list_allocator & = delete;
+
+    //! Allocate a block of memory with the given alignment.
+    //!
+    //! @param size The size of the block to allocate
+    //! @param alignment The desired alignment of the allocated block
+    //! @return A pointer to the beginning of the block on success, @p nullptr otherwise.
+    [[nodiscard]] auto allocate(std::size_t size, std::align_val_t alignment) noexcept -> void * override;
+
+    //! Deallocate a block of memory previously allocated.
+    //!
+    //! @param block The pointer to the block to free.
+    auto deallocate(void * block) noexcept -> void override;
+
+  private:
+    struct block_header final
+    {
+      std::size_t size;
+      bool free;
+      block_header * next;
+      block_header * prev;
+    };
+
+    //! Try to expand the heap to accommodate the given size.
+    //!
+    //! @param delta The size to expand the heap by.
+    //! @return @p true if the heap was expanded, @p false otherwise.
+    auto expand(std::size_t delta) noexcept -> bool;
+
+    //! Split a given free block to accommodate and allocation.
+    //!
+    //! The newly split free block is inserted into the free list.
+    //!
+    //! @param block The block to split.
+    //! @param size The size of the allocation.
+    //! @param padding The amount of padding to apply.
+    auto split(block_header * block, std::size_t size, std::size_t padding) noexcept -> void;
+
+    //! Try to coalesce a given block with it's preceding and/or following block.
+    //!
+    //! @param block The block to coalesce.
+    auto coalesce(block_header * block) noexcept -> void;
+
+    kapi::memory::linear_address m_base;
+    kapi::memory::linear_address m_frontier;
+    block_header * m_free_list;
+
+    kstd::mutex m_lock;
+  };
+
+}  // namespace kernel::memory
+
+#endif
+\ No newline at end of file
diff --git a/kernel/include/kernel/memory/heap_allocator.hpp b/kernel/include/kernel/memory/heap_allocator.hpp
new file mode 100644
index 0000000..bc771e3
--- /dev/null
+++ b/kernel/include/kernel/memory/heap_allocator.hpp
@@ -0,0 +1,32 @@
+#ifndef TEACHOS_KERNEL_MEMORY_HEAP_ALLOCATOR_HPP
+#define TEACHOS_KERNEL_MEMORY_HEAP_ALLOCATOR_HPP
+
+#include <kstd/mutex>
+
+#include <cstddef>
+#include <new>
+
+namespace kernel::memory
+{
+
+  //! The interface for all kernel heap allocators.
+  struct heap_allocator
+  {
+    virtual ~heap_allocator() = default;
+
+    //! Allocate a block of memory with the given alignment.
+    //!
+    //! @param size The size of the block to allocate
+    //! @param alignment The desired alignment of the allocated block
+    //! @return A pointer to the beginning of the block on success, @p nullptr otherwise.
+    [[nodiscard]] virtual auto allocate(std::size_t size, std::align_val_t alignment) noexcept -> void * = 0;
+
+    //! Deallocate a block of memory previously allocated.
+    //!
+    //! @param block The pointer to the block to free.
+    virtual auto deallocate(void * block) noexcept -> void = 0;
+  };
+
+}  // namespace kernel::memory
+
+#endif
+\ No newline at end of file