#pypp 0
// Iris: micro-kernel for a capability-based operating system.
// memory.ccp: Page allocation system.
// Copyright 2009 Bas Wijnen <wijnen@debian.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#include "kernel.hh"
//#define DEBUG_ALLOC

extern unsigned _end

static void clear_page (unsigned page, unsigned num = 1):
	#ifdef DEBUG_ALLOC
	kdebug ("clearing page ")
	kdebug_num (page)
	kdebug ("+")
	kdebug_num (num << PAGE_BITS)
	kdebug ('\n')
	#endif
	page = (page & ~0xc0000000) | 0xa0000000
	for unsigned p = 0; p < num; ++p:
		arch_uncache_page (page - 0x20000000 + (p << PAGE_BITS))
		for unsigned i = 0; i < (1 << (PAGE_BITS - 2)); ++i:
			// Clear page.
			((unsigned *)page)[(p << PAGE_BITS - 2) + i] = 0
	if *(unsigned *)page != 0 || ((unsigned *)page)[(num << (PAGE_BITS - 2)) - 1] != 0:
		kdebug_num ((num << (PAGE_BITS - 2)) - 1)
		kdebug ("/")
		kdebug_num (((unsigned *)page)[(num << (PAGE_BITS - 2)) - 1])
		kdebug (",")
		kdebug_num (*(unsigned *)page)
		kdebug ("\n")
		dpanic (0, "clear_page didn't work")

#if 0

static unsigned free_begin
static unsigned free_end

unsigned init_memory (unsigned mem):
	free_begin = ((unsigned)&_end + ~PAGE_MASK) & PAGE_MASK
	free_end = (0x80000000 + mem) & PAGE_MASK
	return (free_end - free_begin) >> PAGE_BITS

unsigned phys_alloc (unsigned num):
	if free_begin + num * PAGE_SIZE > free_end:
		kdebug ("memory allocation failed\n")
		return 0
	unsigned ret = free_begin
	free_begin += num * PAGE_SIZE
	clear_page (ret, num)
	return ret

void phys_free (unsigned page, unsigned num):
	// Not supported.

#ifndef NDEBUG
/*void check_impl (kObject *o, unsigned num, char const *msg):
//	for ; o; o = (kObject *)o->next:
//		if (unsigned)o >= (unsigned)free_begin && (unsigned)o < (unsigned)free_end:
*/ //			panic (num, msg)
bool check_free (kObject *o, unsigned size):
	return true
void print_free ():
#endif
#else

struct kFreePages:
	kFreePages *prev, *next
	unsigned num

static kFreePages *first_free

unsigned init_memory (unsigned mem):
	first_free = (kFreePages *)(((unsigned)&_end + ~PAGE_MASK) & PAGE_MASK)
	first_free->prev = NULL
	first_free->next = NULL
	first_free->num = ((mem & PAGE_MASK) - ((unsigned)first_free & ~0xc0000000)) >> PAGE_BITS
	#ifdef DEBUG_ALLOC
	kdebug ("initial memory: ")
	kdebug_num ((unsigned)first_free & ~0xc0000000)
	kdebug ("+")
	kdebug_num (first_free->num)
	kdebug ("\n")
	#endif
	return first_free->num

#ifdef DEBUG_ALLOC
static bool is_free (unsigned page):
	for kFreePages *p = first_free; p; p = p->next:
		if page >= (unsigned)p && page < (unsigned)p + (p->num << PAGE_BITS):
			return true
	return false
#endif

unsigned phys_alloc (unsigned num):
	kFreePages *choice = NULL
	for kFreePages *p = first_free; p; p = p->next:
		if p->num < num:
			continue
		if choice && choice->num < p->num:
			continue
		if p->num == num:
			if p->prev:
				p->prev->next = p->next
			else:
				first_free = p->next
			if p->next:
				p->next->prev = p->prev
			clear_page ((unsigned)p, num)
			#ifdef DEBUG_ALLOC
			kdebug ("allocating ")
			kdebug_num ((unsigned)p & ~0xc0000000)
			kdebug ("+")
			kdebug_num (num << PAGE_BITS)
			kdebug ("\n")
			if is_free ((unsigned)p):
				panic ((unsigned)p, "page still free after allocation")
			#endif
			return (unsigned)p
		choice = p
	if !choice:
		// TODO: reorganizing may work to allow allocation.
		dpanic (0x03948859, "range memory allocation failed")
		return 0
	choice->num -= num
	unsigned ret = (unsigned)choice + (choice->num << PAGE_BITS)
	clear_page (ret, num)
	#ifdef DEBUG_ALLOC
	kdebug ("allocating ")
	kdebug_num (ret & ~0xc0000000)
	kdebug ("+")
	kdebug_num (num << PAGE_BITS)
	kdebug ("\n")
	if is_free (ret):
		panic (ret, "page still free after allocation")
	#endif
	return ret

void phys_free (unsigned page, unsigned num):
	#ifdef DEBUG_ALLOC
	kdebug ("free ")
	kdebug_num (page & ~0xc0000000)
	kdebug ("+")
	kdebug_num (num << PAGE_BITS)
	kdebug ("\n")
	if is_free (page):
		panic (page, "page already free")
	#endif
	unsigned size = num << PAGE_BITS
	if !first_free || (unsigned)first_free > page:
		// This is the first free block.
		kFreePages *n = (kFreePages *)page
		n->prev = NULL
		if (unsigned)first_free == page + size:
			// It fits exactly before the previous first free block.
			n->next = first_free->next
			n->num = num + first_free->num
		else:
			// It is a new block.
			n->next = first_free
			n->num = num
		first_free = n
		if n->next:
			n->next->prev = n
		return
	kFreePages *p
	for p = first_free; p->next && (unsigned)p->next < page; p = p->next:
		// Do nothing.
		if p == p->next:
			dpanic (0, "page is its own next")
	// The new block should be inserted directly after p.
	if (unsigned)p->next == page + size:
		// It can be merged with the block after it: do that.
		kFreePages *n = (kFreePages *)page
		n->prev = p
		n->next = p->next->next
		if n->next:
			n->next->prev = n
		n->num = num + p->next->num
		p->next = n
		if (unsigned)p + (p->num << PAGE_BITS) == (unsigned)n:
			// It can also be merged with the page before it: do that as well.
			p->num += n->num
			p->next = n->next
			if p->next:
				p->next->prev = p
		return
	// The new block cannot be merged with the block after it.
	if (unsigned)p + (p->num << PAGE_BITS) == page:
		// But it can be merged with the one before it: do that.
		p->num += num
		return
	// The new block cannot be merged at all.
	kFreePages *n = (kFreePages *)page
	n->next = p->next
	n->prev = p
	if n->next:
		n->next->prev = n
	p->next = n
	n->num = num

#ifndef NDEBUG
bool check_free (kObject *o, unsigned size):
	for kFreePages *p = first_free; p; p = p->next:
		if (unsigned)o + size > (unsigned)p && (unsigned)o < (unsigned)p + p->num * PAGE_SIZE:
			return false
	return true

void print_free ():
	kdebug ("Free pages: ")
	for kFreePages *p = first_free; p; p = p->next:
		kdebug_num ((unsigned)p)
		kdebug (":")
		kdebug_num (p->num, 4)
		kdebug ("->")
	kdebug ("NULL\n")
#endif
#endif

#ifndef NDEBUG
void check_memory (kMemory *mem, unsigned num, char const *msg):
	check_impl (mem->pages, num, msg)
	check_impl (mem->threads, num, msg)
	check_impl (mem->receivers, num, msg)
	for kReceiver *r = mem->receivers; r; r = (kReceiver *)r->next:
		check_impl (r->messages, num, msg)
	check_impl (mem->capses, num, msg)
	check_impl (mem->memories, num, msg)
	for kMemory *m = mem->memories; m; m = (kMemory *)m->next:
		check_memory (m, num, msg)

void check (unsigned num, char const *msg):
	check_memory (&top_memory, num, msg)
	top_memory.check (num)
#endif

unsigned raw_zalloc ():
	return phys_alloc (1)

void raw_pfree (unsigned page):
	return phys_free (page, 1)

unsigned kMemory::zalloc ():
	if !use ():
		dpanic (0x34638920, "limit reached: allocation not allowed")
		kdebug ("limit reached: allocation not allowed\n")
		return NULL
	return raw_zalloc ()

void kMemory::pfree (unsigned page):
	unuse ()
	return raw_pfree (page)

unsigned kMemory::palloc ():
	return zalloc ()

void kMemory::zfree (unsigned page):
	pfree (page)