Implement first-pass simple virtual memory manager

src/kernel/memory.h

@@ -3,21 +3,44 @@
 /// The block memory manager and related definitions.
 
 #include <stddef.h>
+#include <stdint.h>
+
+struct memory_block_node;
 
 /// Manager for allocation of virtual memory.
 class memory_manager
 {
 public:
 	memory_manager();
+	memory_manager(void *start, size_t length);
 
-	memory_manager(const memory_manager &) = delete;
+	/// Allocate memory from the area managed.
+	/// \arg length  The amount of memory to allocate, in bytes
+	/// \returns     A pointer to the allocated memory, or nullptr if
+	///              allocation failed.
+	void * allocate(size_t length);
+
+	/// Free a previous allocation.
+	/// \arg p  A pointer previously retuned by allocate()
+	void free(void *p);
 
 private:
 	friend class page_manager;
+
+	// Simple incrementing pointer.
+	void *m_start;
+	size_t m_length;
+
+	memory_manager(const memory_manager &) = delete;
 };
 
-extern memory_manager g_memory_manager;
+extern memory_manager g_kernel_memory_manager;
 
 /// Bootstrap the memory managers.
 void memory_initialize_managers(const void *memory_map, size_t map_length, size_t desc_length);
 
+/// Allocate kernel space memory.
+/// \arg length  The amount of memory to allocate, in bytes
+/// \returns     A pointer to the allocated memory, or nullptr if
+///              allocation failed.
+inline void * kalloc(size_t length) { return g_kernel_memory_manager.allocate(length); }