/*-
 * Copyright (c) 2002-2018 The UbixOS Project.
 * All rights reserved.
 *
 * This was developed by Christopher W. Olsen for the UbixOS Project.
 *
 * 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, the following disclaimer and the list of authors.
 * 2) Redistributions in binary form must reproduce the above copyright notice, this list of
 *    conditions, the following disclaimer and the list of authors in the documentation and/or
 *    other materials provided with the distribution.
 * 3) Neither the name of the UbixOS Project 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 AUTHOR 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 COPYRIGHT OWNER 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 <vmm/vmm.h>
#include <ubixos/sched.h>
#include <ubixos/kpanic.h>
#include <ubixos/spinlock.h>
#include <lib/kprintf.h>

static struct spinLock fvpSpinLock = SPIN_LOCK_INITIALIZER;

/************************************************************************

 Function: void *vmm_getFreeVirtualPage(pidType pid,int count);
 Description: Returns A Free Page Mapped To The VM Space
 Notes:

 2016-01-21 MrOlsen - I'm not 100% happy with this, i know I can make the calculations much faster

 08/11/02 - This Will Return Next Avilable Free Page Of Tasks VM Space

 ************************************************************************/
void *vmm_getFreeVirtualPage(pidType pid, int count, int type) {
  int y = 0, counter = 0, pdI = 0x0, ptI = 0x0;

  uint32_t *pageDirectory = 0x0;
  uint32_t *pageTable = 0x0;

  uint32_t start_page = 0x0;

  spinLock(&fvpSpinLock);

  pageDirectory = (uint32_t *) PD_BASE_ADDR;

  /* Lets Search For A Free Page */
  if (_current->oInfo.vmStart <= 0x100000)
    kpanic("Invalid vmStart\n");

  /* Get Our Starting Address */
  if (type == VM_THRD) {
    start_page = (uint32_t) (_current->td.vm_daddr + ctob(_current->td.vm_dsize));
  }
  else if (type == VM_TASK) {
    start_page = _current->oInfo.vmStart;
  }
  else
    K_PANIC("Invalid Type");


    /* Locate Initial Page Table */
    pdI = ((start_page + (counter * PAGE_SIZE)) / (PD_ENTRIES * PAGE_SIZE));

    keepMapping:

    if ((pageDirectory[pdI] & PAGE_PRESENT) != PAGE_PRESENT) { /* If Page Directory Is Not Yet Allocated Allocate It */


      /* Map A Page Directory Into The Page Table */
      pageDirectory[pdI] = (uint32_t) vmm_findFreePage(_current->id) | PAGE_DEFAULT;

      /* Also Add It To Virtual Space So We Can Make Changes Later */
      pageTable = (uint32_t *) (PT_BASE_ADDR + (PD_INDEX( PT_BASE_ADDR ) * PAGE_SIZE)); /* Table that maps that 4MB */

      pageTable[pdI] = (pageDirectory[pdI] & 0xFFFFF000) | PAGE_DEFAULT;

      /* Reload Page Directory */
      asm(
        "movl %cr3,%eax\n"
        "movl %eax,%cr3\n"
      );

      pageTable = (uint32_t *) (PT_BASE_ADDR + (pdI * 0x1000));
      bzero(pageTable, PAGE_SIZE);
    }
    else {
      pageTable = (uint32_t *) (PT_BASE_ADDR + (0x1000 * pdI));
    }

    ptI = ((start_page - (pdI * (PD_ENTRIES * PAGE_SIZE))) / PAGE_SIZE);

  for (y = ptI; y < PT_ENTRIES && counter < count; y++, counter++) {

      /* Loop Through The Page Table Find An UnAllocated Page */
    if ((pageTable[y] & PAGE_PRESENT) == PAGE_PRESENT) {
      if ((pageTable[y] & PAGE_COW) == PAGE_COW)
        kprintf("COW PAGE NOT CLEANED!");

      start_page += (PAGE_SIZE * counter);
      pdI = ((start_page + (counter * PAGE_SIZE)) / (PD_ENTRIES * PAGE_SIZE));
      counter = 0;
      goto keepMapping;
      }

      else if ((uint32_t) pageTable[y] == (uint32_t) 0x0) {
      if ((vmm_remapPage((uint32_t) vmm_findFreePage(pid), ((pdI * (PD_ENTRIES * PAGE_SIZE)) + (y * PAGE_SIZE)), PAGE_DEFAULT, pid)) == 0x0)
        kpanic("vmmRemapPage: getFreeVirtualPage-1: (%i)[0x%X]\n", type, ((pdI * (PD_ENTRIES * PAGE_SIZE)) + (y * PAGE_SIZE)));

      vmm_clearVirtualPage((uInt32) ((pdI * (PD_ENTRIES * PAGE_SIZE)) + (y * PAGE_SIZE)));
      }
      else {
        kprintf("-> y: %i, ptI: 0x%X, pdI: 0x%X pTS: 0x%X ??\n", y, ptI, pdI, pageTable[y]);
        K_PANIC("UHM HOW DO WE HAVE AN ALLOCATED PAGE HERE!!\n");
      }
    }
    if (counter < count) {
    start_page += (PAGE_SIZE * counter);
    pdI = ((start_page + (counter * PAGE_SIZE)) / (PD_ENTRIES * PAGE_SIZE));
      goto keepMapping;
    }



  gotPages:
  if (type == VM_THRD) {
    _current->td.vm_dsize += btoc(count * PAGE_SIZE);
  }
  else if (type == VM_TASK)
    _current->oInfo.vmStart += (count * PAGE_SIZE);


  spinUnlock(&fvpSpinLock);
  return (start_page);
}