#pypp 0
#ifndef _KERNEL_HH
#define _KERNEL_HH

#ifndef EXTERN
#define EXTERN extern
#endif

#define NULL 0

struct Object_base
struct Object
struct Page
struct Thread
struct Memory

#include "arch.hh"

struct Object_base:
	// Next and previous object of any type in the same page.
	Object *prev_obj, *next_obj
	void free_obj (Memory *parent)
	inline bool is_free ()

template <typename _T> struct Object : public Object_base:
	// Next and previous object of the same type in any page.
	_T *prev, *next
	void free (Memory *parent, _T *&first)

struct Free : public Object <Free>
	// This marker is ~0.  No other kernel structure may allow this value
	// at this point.  It is used to recognize free chunks.
	unsigned marker

bool Object_base::is_free ():
	return ((Free *)this)->marker == ~0

struct Page : public Object <Page>:
	void *physical

struct Thread : public Object <Thread>:
	Memory *address_space
	unsigned pc, sp
	Thread_arch arch
	Thread *schedule_prev, *schedule_next

struct Memory : public Object <Memory>:
	Free *frees
	Page *pages
	Thread *threads
	Memory *memories
	unsigned limit, used
	Memory_arch arch

	// Allocation of pages.
	void *palloc ()
	void *zalloc ()
	void pfree (void *page)
	void zfree (void *page)

	// Allocation routines for kernel structures
	void *search_free (unsigned size, void *&first)
	Page *alloc_page ()
	Thread *alloc_thread ()
	Memory *alloc_memory ()

// Functions which can be called from assembly must not be mangled.
extern "C":
	// Panic.  n is sent over caps led.  message is currently ignored.
	void panic (unsigned n, char const *message)
	// Debug: switch caps led
	void led (bool on, bool tick)

struct FreePage:
	FreePage *next

EXTERN FreePage *zero_pages, *junk_pages
EXTERN Memory top_memory
EXTERN Thread *sleepers, *runners
EXTERN Thread idle
EXTERN Memory idle_memory
EXTERN Page idle_page

template <typename _T> void Object <_T>::free (Memory *parent, _T *&first):
	if prev:
		prev->next = next
	else:
		first = next
	if next:
		next->prev = prev
	free_obj (parent)

#endif