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 $Id: getfreevirtualpage.c 230 2016-01-24 01:36:51Z reddawg $

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

#include <vmm/vmm.h>
#include <ubixos/sched.h>
#include <ubixos/kpanic.h>
#include <ubixos/spinlock.h>
#include <lib/kprintf.h>

static spinLock_t fvpSpinLock = SPIN_LOCK_INITIALIZER;

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

 Function: void *vmmGetFreeVirtualPage(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 *vmmGetFreeVirtualPage( pidType pid, int count, int type ) {
  int y = 0, counter = 0, pdI = 0x0, ptI = 0x0;
  u_int32_t *pageTableSrc = 0x0;
  u_int32_t *pageDir = 0x0;
  u_int32_t start_page = 0x0;

  spinLock( &fvpSpinLock );

  pageDir = (uInt32 *) 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 = (u_int32_t)( _current->td.vm_daddr + ctob( _current->td.vm_dsize ) );
  }
  else if ( type == VM_TASK ) {
    //kprintf("vmStart");
    start_page = _current->oInfo.vmStart;
  }
  else
    K_PANIC( "Invalid Type" );

  //kprintf( "Entering MMAP: Type: %i, Returning %i Pages At Address: 0x%X\n", type, count, start_page );

  /*
   *
   * I Need To Write Some Function For Space That Is Returned Maybe A Malloc Type Map
   *
   */

  /*
   * Lets Start Allocating Pages
   */

  for ( counter = 0; counter < count; counter++ ) {
    /* Locate Initial Page Table */
    pdI = ((start_page + (counter * 0x1000)) / 0x400000);

    /* If Page Directory Is Not Yet Allocated Allocate It */
    if ( (pageDir[pdI] & PAGE_PRESENT) != PAGE_PRESENT ) {
      pageDir[pdI] = (uInt32) vmmFindFreePage( _current->id ) | PAGE_DEFAULT;

      /* Also Add It To Virtual Space So We Can Make Changes Later */
      pageTableSrc = (uInt32 *) (PT_BASE_ADDR + (4096 * 767));
      pageTableSrc[pdI] = pageDir[pdI];

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

      pageTableSrc = (uInt32 *) (PT_BASE_ADDR + (0x1000 * pdI));

      /* Initialize The New Page Table To Prevent Dirty Bits */
      for ( y = 0x0; y < PD_ENTRIES; y++ ) {
        pageTableSrc[y] = (uInt32) 0x0;
      }

    }
    else {
      pageTableSrc = (uInt32 *) (PT_BASE_ADDR + (0x1000 * pdI));
    }

    ptI = ((start_page - (pdI * 0x400000)) / 0x1000);

    for ( y = ptI; y < 1024 && counter < count; y++ ) {

      /* Loop Through The Page Table Find An UnAllocated Page */
      if ( (pageTableSrc[y] & PAGE_COW) == PAGE_COW ) {
        kprintf( "COW PAGE NOT CLEANED!" );
      }
      else if ( (uInt32) pageTableSrc[y] == (uInt32) 0x0 ) {
        if ( (vmm_remapPage( (uInt32) vmmFindFreePage( pid ), ((pdI * (1024 * 4096)) + (y * 4096)), PAGE_DEFAULT )) == 0x0 )
          kpanic( "vmmRemapPage: getFreeVirtualPage-1: (%i)[0x%X]\n", type, ((pdI * (1024 * 4096)) + (y * 4096)) );
        vmmClearVirtualPage( (uInt32)( (pdI * (1024 * 4096)) + (y * 4096) ) );
      }
      else {
        kprintf( "-> y: %i, ptI: 0x%X, pdI: 0x%X pTS: 0x%X ??\n", y, ptI, pdI, pageTableSrc[y] );
        K_PANIC( "UHM HOW DO WE HAVE AN ALLOCATED PAGE HERE!!\n" );
      }
      counter++;

    }
  }

  if ( type == VM_THRD ) {
    _current->td.vm_dsize += btoc( count * 0x1000 );
    kprintf( "vm_dsize: [0x%X]][0x%X]\n", ctob( _current->td.vm_dsize ), _current->td.vm_dsize );
  }
  else if ( type == VM_TASK )
    _current->oInfo.vmStart += count * 0x1000;

  /*
   * MMAP Return
   */

  kprintf( "mmap: [0x%x]\n", start_page );
  /* If No Free Page Was Found Return NULL */
  spinUnlock( &fvpSpinLock );
  return (start_page);
}

/***
 END
 ***/