Rewrote physical memory allocator

The physical memory allocator now uses a buddy allocator instead of a stack.

Also moved some of the platform-independent context code to kernel.c.

include/platform/context.h

@@ -1,19 +1,35 @@
-#pragma once
+#ifndef _QUARK_CONTEXT_H
+#define _QUARK_CONTEXT_H
 
-struct process_context_t;
+#include <stdint.h>
+
+#if defined __i386__ || defined __x86_64__
+#define DEFAULT_FLAGS 0x3200
+#endif
 
 /**
- * @brief Allocates a new process context and initializes it with the given 
- * program counter.
+ * @brief Stores the context of a particular process. The contents of this
+ * struct are platform-specific.
  * 
- * @param task_entry 
- * @return void* 
  */
-void *initialize_context(void *pc);
+struct process_context_t
+{
 
-void destroy_context(void *ctx);
+#if defined __i386__
+    uint32_t gp_registers[8];
+    uint32_t ss;
+    uint32_t cs;
+    uint32_t eip;
+    uint32_t flags;
+#elif defined __x86_64__
+    uint64_t gp_registers[16];
+    uint64_t ss;
+    uint64_t cs;
+    uint64_t rip;
+    uint64_t flags;
+#endif
 
-void save_context(struct process_context_t *context);
+};
 
 void load_context(struct process_context_t *context);
 
@@ -24,3 +40,5 @@ void set_context_stack(struct process_context_t *context, void *stack);
 void set_context_flags(struct process_context_t *context, unsigned long flags);
 
 void set_context_return(struct process_context_t *context, unsigned long value);
+
+#endif