/*
 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
 *	The President and Fellows of Harvard College.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <types.h>
#include <kern/errno.h>
#include <lib.h>
#include <addrspace.h>
#include <vm.h>
#include <mips/tlb.h>
#include <spl.h>
#include <proc.h>

/*
 * Note! If OPT_DUMBVM is set, as is the case until you start the VM
 * assignment, this file is not compiled or linked or in any way
 * used. The cheesy hack versions in dumbvm.c are used instead.
 */

struct addrspace *
as_create(void)
{
	struct addrspace *as;

	as = kmalloc(sizeof(struct addrspace));
	if (as == NULL) {
		return NULL;
	}

	/*
	 * Initialize as needed.
	 */

	as->region_base = NULL;
	as->pte_base = NULL;

	return as;
}

int
as_copy(struct addrspace *old, struct addrspace **ret)
{
	struct addrspace *newas;

	newas = as_create();
	if (newas==NULL) {
		return ENOMEM;
	}

	/*
	 * Write this.
	 */

	(void)old;

	*ret = newas;
	return 0;
}

void
as_destroy(struct addrspace *as)
{
	/*
	 * Clean up as needed.
	 */

	kfree(as);
}

void
as_activate(void)
{
	struct addrspace *as;

	as = proc_getas();
	if (as == NULL) {
		/*
		 * Kernel thread without an address space; leave the
		 * prior address space in place.
		 */
		return;
	}

	// Same as dumbvm for now

	/* Disable interrupts on this CPU while frobbing the TLB. */
	int spl = splhigh();

	for (int i = 0; i < NUM_TLB; i++) {
		tlb_write(TLBHI_INVALID(i), TLBLO_INVALID(), i);
	}

	splx(spl);
}

void
as_deactivate(void)
{
	/*
	 * Write this. For many designs it won't need to actually do
	 * anything. See proc.c for an explanation of why it (might)
	 * be needed.
	 */
}

/*
 * Set up a segment at virtual address VADDR of size MEMSIZE. The
 * segment in memory extends from VADDR up to (but not including)
 * VADDR+MEMSIZE.
 *
 * The READABLE, WRITEABLE, and EXECUTABLE flags are set if read,
 * write, or execute permission should be set on the segment. At the
 * moment, these are ignored. When you write the VM system, you may
 * want to implement them.
 */
int
as_define_region(struct addrspace *as, vaddr_t vaddr, size_t sz,
		 int readable, int writeable, int executable)
{

	KASSERT(as != NULL);
	struct region_node *new_region;
	size_t npages;

	/* Align the region. First, the base... */
	sz += vaddr & ~(vaddr_t)PAGE_FRAME;
	vaddr &= PAGE_FRAME;

	/* ...and now the length. */
	sz = (sz + PAGE_SIZE - 1) & PAGE_FRAME;

	npages = sz / PAGE_SIZE;

	if(as->region_base == NULL)
	{
		new_region = kmalloc(sizeof(struct region_node));
		if(new_region == NULL)
		{
			return ENOMEM;
		}
		as->region_base = new_region;
	}
	else
	{
		new_region = as->region_base;
		while(new_region->next != NULL)
		{
			new_region = new_region->next;
		}
		
		new_region->next = kmalloc(sizeof(struct region_node));
		
		if(new_region->next == NULL)
		{
			return ENOMEM;
		}
		new_region = new_region->next;
	}
	

	new_region->start_vaddr = vaddr;
	new_region->size = sz;
	new_region->npages = npages;
	new_region->next = NULL;

	/* all pages are read-write for now */
	(void)readable;
	(void)writeable;
	(void)executable;

	return 0;
}

int as_prepare_load(struct addrspace *as)
{
	/*
	 * Write this.
	 */

	(void)as;
	return 0;
}

int as_complete_load(struct addrspace *as)
{
	/*
	 * Write this.
	 */

	(void)as;
	return 0;
}

int as_define_stack(struct addrspace *as, vaddr_t *stackptr)
{
	/*
	 * Write this.
	 */

	(void)as;

	/* Initial user-level stack pointer */
	*stackptr = USERSTACK;

	return 0;
}