/* Copyright (C) 2008  Emmanuel Varoquaux

   This file is part of XOS.

   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 "tlb.h"

#include <kmalloc.h>
#include <system.h>
#include <system_data_structs.h>
#include <i386.h>

static int resolve_laddr_alloc(unsigned long laddr, unsigned long **page_table_entry)
{
  struct linear_address_data_struct laddr_dat;
  unsigned long *page_dir;
  struct page_table_entry_data_struct pte_dat;
  unsigned long *page_table;

  get_linear_address(&laddr, &laddr_dat);

  /* adresse de la table des pages de premier niveau */
  get_pdbr(page_dir);

  /* adresse de la table des pages de second niveau */
  get_page_table_entry(&page_dir[laddr_dat.dir], &pte_dat);
  if (pte_dat.present)
    page_table = (unsigned long *)pte_dat.page_frame_addr;
  else {
    if (!(page_table = kmalloc(PAGE_SIZE)))
      return 0;
    clear_page_table(page_table);
    pte_dat.present = 1;
    pte_dat.rw = 1;
    pte_dat.us = 1;
    pte_dat.accessed = 0;
    pte_dat.dirty = 0;
    pte_dat.avail = 0;
    pte_dat.page_frame_addr = (unsigned long)page_table;
    set_page_table_entry(&page_dir[laddr_dat.dir], &pte_dat);
  }

  *page_table_entry = &page_table[laddr_dat.page];
  return 1;
}

static int resolve_laddr_noalloc(unsigned long laddr, unsigned long **page_table_entry)
{
  struct linear_address_data_struct laddr_dat;
  unsigned long *page_dir;
  struct page_table_entry_data_struct pte_dat;
  unsigned long *page_table;

  get_linear_address(&laddr, &laddr_dat);

  /* adresse de la table des pages de premier niveau */
  get_pdbr(page_dir);

  /* adresse de la table des pages de second niveau */
  get_page_table_entry(&page_dir[laddr_dat.dir], &pte_dat);
  if (!pte_dat.present)
    return 0;
  page_table = (unsigned long *)pte_dat.page_frame_addr;

  *page_table_entry = &page_table[laddr_dat.page];
  return 1;
}

int set_page(unsigned long laddr, unsigned long page_frame, int rw)
{
  unsigned long *page_table_entry;
  struct page_table_entry_data_struct pte_dat;

  if (!resolve_laddr_alloc(laddr, &page_table_entry))
    return 0;
  pte_dat.present = 1;
  pte_dat.rw = rw;
  pte_dat.us = 1;
  pte_dat.accessed = 0;
  pte_dat.dirty = 0;
  pte_dat.avail = 0;
  pte_dat.page_frame_addr = page_frame;
  set_page_table_entry(page_table_entry, &pte_dat);
  invalidate_entry(laddr);
  return 1;
}

int get_page_frame_addr(unsigned long laddr, unsigned long *page_frame)
{
  unsigned long *page_table_entry;
  struct page_table_entry_data_struct pte_dat;

  if (!resolve_laddr_noalloc(laddr, &page_table_entry))
    return 0;
  get_page_table_entry(page_table_entry, &pte_dat);
  if (!pte_dat.present)
    return 0;
  *page_frame = pte_dat.page_frame_addr;
  return 1;
}

int get_page_rw(unsigned long laddr, int *rw)
{
  unsigned long *page_table_entry;
  struct page_table_entry_data_struct pte_dat;

  if (!resolve_laddr_noalloc(laddr, &page_table_entry))
    return 0;
  get_page_table_entry(page_table_entry, &pte_dat);
  if (!pte_dat.present)
    return 0;
  *rw = pte_dat.rw;
  return 1;
}

int set_page_rw(unsigned long laddr, int rw)
{
  unsigned long *page_table_entry;
  struct page_table_entry_data_struct pte_dat;

  if (!resolve_laddr_noalloc(laddr, &page_table_entry))
    return 0;
  get_page_table_entry(page_table_entry, &pte_dat);
  if (!pte_dat.present)
    return 0;
  pte_dat.rw = rw;
  set_page_table_entry(page_table_entry, &pte_dat);
  invalidate_entry(laddr);
  return 1;
}

void del_page(unsigned long laddr)
{
  unsigned long *page_table_entry;
  struct page_table_entry_data_struct pte_dat;

  if (!resolve_laddr_noalloc(laddr, &page_table_entry))
    return;
  get_page_table_entry(page_table_entry, &pte_dat);
  pte_dat.present = 0;
  set_page_table_entry(page_table_entry, &pte_dat);
  invalidate_entry(laddr);
}