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/kernel.h

@@ -35,8 +35,9 @@ struct boot_info_t
 {
     char *bootloader;
     char *parameters;
-    size_t module_count;
+    size_t memory_size;
     struct memory_map_t map;
+    size_t module_count;
     struct module_t modules[module_limit];
 };
 
@@ -94,9 +95,9 @@ unsigned long kernel_current_pid();
 
 struct process_context_t *kernel_current_context();
 
-enum error_t kernel_store_active_context(struct process_context_t *context, size_t size);
+enum error_t kernel_store_active_context(struct process_context_t *context);
 
-enum error_t kernel_spawn_process(void *program_entry, int priority, physaddr_t address_space);
+unsigned long kernel_spawn_process(void *program_entry, int priority, physaddr_t address_space);
 
 struct process_context_t *kernel_advance_scheduler();
 
@@ -108,11 +109,11 @@ enum error_t kernel_remove_port(unsigned long id);
 
 unsigned long kernel_get_port_owner(unsigned long id);
 
-enum error_t kernel_send_message(int recipient, struct message_t *message);
+enum error_t kernel_send_message(unsigned long recipient, struct message_t *message);
 
-enum error_t kernel_queue_sender(int recipient);
+enum error_t kernel_queue_sender(unsigned long recipient);
 
-enum error_t kernel_queue_message(int recipient, struct message_t *message);
+enum error_t kernel_queue_message(unsigned long recipient, struct message_t *message);
 
 int receive_message(struct message_t *buffer, int flags);
 

include/mmgr.h

@@ -8,10 +8,24 @@
 extern const size_t page_size;
 
 /**
- * @brief Pop the topmost address from the stack and returns that value.
+ * @brief 
  * 
- * If the stack is empty, this function will instead return a status code. This
- * can be identified by testing the least signifigant bits of the return value.
+ * @param size 
+ * @return physaddr_t 
+ */
+physaddr_t reserve_region(size_t size);
+
+/**
+ * @brief 
+ * 
+ * @param location 
+ * @param size 
+ * @return int 
+ */
+int free_region(physaddr_t location, size_t size);
+
+/**
+ * @brief Reserves a single page and returns its physical address.
  * 
  * @param stack 
  * @return physaddr_t 
@@ -19,9 +33,7 @@ extern const size_t page_size;
 physaddr_t reserve_page();
 
 /**
- * @brief Pushes `location` onto the stack.
- * 
- * If there is no room on the stack, the stack will be unaffected.
+ * @brief Marks the page at the given location as free.
  * 
  * @param stack 
  * @param location 
@@ -41,22 +53,25 @@ size_t free_page_count();
  * 
  * @return void* 
  */
-void *page_stack_bottom();
+void *page_map_base();
 
 /**
  * @brief Get the location of the top of the page stack.
  * 
  * @return void* 
  */
-void *page_stack_top();
+void *page_map_end();
 
 /**
- * @brief Push all available pages in `map` onto the stack
+ * @brief Constructs the bitmaps used by the physical memory allocator.
  * 
- * @param stack 
  * @param map 
+ * @param base 
+ * @param memory_size 
+ * @param block_size 
+ * @return enum error_t 
  */
-int initialize_page_stack(struct memory_map_t *map, physaddr_t *stack_base);
+enum error_t initialize_page_map(struct memory_map_t *map, void *base, size_t memory_size, unsigned long block_size);
 
 /**
  * @brief Create a new top-level page table and map the kernel in it.

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

include/x86/processstate.h

@@ -1,21 +0,0 @@
-#pragma once
-
-#include <stdint.h>
-
-#define PCB_LOCATION 0x800
-
-struct process_context_t
-{
-    uint32_t eax;
-    uint32_t ebx;
-    uint32_t ecx;
-    uint32_t edx;
-    uint32_t edi;
-    uint32_t esi;
-    uint32_t ebp;
-    uint32_t ss;
-    uint32_t esp;
-    uint32_t cs;
-    uint32_t eip;
-    uint32_t flags;
-};