/*****************************************************************************************
 Copyright (c) 2002 The UbixOS Project
 All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are
permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of
conditions, the following disclaimer and the list of authors.  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. 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 COPYRIGHT HOLDERS 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.

 $Id$

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

#include <vmm/vmm.h>
#include <ubixos/kpanic.h>
#include <ubixos/spinlock.h>

static spinLock_t vmmGFPlock = SPIN_LOCK_INITIALIZER;

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

Function: void *vmmGetFreePage(pidType pid);

Description: Returns A Free Page Mapped To The VM Space

Notes:

07/30/02 - This Returns A Free Page In The Top 1GB For The Kernel

************************************************************************/
void           *
vmmGetFreePage(pidType pid)
{
  uInt16             x = 0x0, y = 0x0;
  uInt32         *pageTableSrc = 0x0;
  
  spinLock(&vmmGFPlock);
  
  /* Lets Search For A Free Page */
  for (x = 768; x < 1024; x++) {

    /* Set Page Table Address */
    pageTableSrc = (uInt32 *) (tablesBaseAddress + (0x1000 * x));
    for (y = 0x0; y < 1024; y++) {
      /* Loop Through The Page Table Find An UnAllocated Page */
      if ((uInt32) pageTableSrc[y] == (uInt32) 0x0) {
	/* Map A Physical Page To The Virtual Page */
	if ((vmm_remapPage(vmmFindFreePage(pid), ((x * 0x400000) + (y * 0x1000)),KERNEL_PAGE_DEFAULT)) == 0x0)
	  kpanic("vmmRemapPage: vmmGetFreePage\n");
	/* Clear This Page So No Garbage Is There */
	vmmClearVirtualPage((uInt32) ((x * 0x400000) + (y * 0x1000)));
	/* Return The Address Of The Newly Allocate Page */
	spinUnlock(&vmmGFPlock);
	return ((void *)((x * 0x400000) + (y * 0x1000)));
      }
    }
  }
  /* If No Free Page Was Found Return NULL */
  spinUnlock(&vmmGFPlock);
  return (0x0);
}

/***
 $Log$
 Revision 1.2  2005/10/12 00:13:38  reddawg
 Removed

 Revision 1.1.1.1  2005/09/26 17:24:50  reddawg
 no message

 Revision 1.6  2004/09/11 16:57:27  apwillia
 Add locking get GetFreePage

 Revision 1.5  2004/07/28 15:05:43  reddawg
 Major:
   Pages now have strict security enforcement.
   Many null dereferences have been resolved.
   When apps loaded permissions set for pages rw and ro

 Revision 1.4  2004/07/28 00:17:05  reddawg
 Major:
   Disconnected page 0x0 from the system... Unfortunately this broke many things
   all of which have been fixed. This was good because nothing deferences NULL
   any more.

 Things affected:
   malloc,kmalloc,getfreepage,getfreevirtualpage,pagefault,fork,exec,ld,ld.so,exec,file

 Revision 1.3  2004/07/24 23:04:44  reddawg
 Changes... mark let me know if you fault at pid 185 when you type stress

 Revision 1.2  2004/07/20 22:29:55  reddawg
 assert: remade assert

 Revision 1.1.1.1  2004/04/15 12:06:51  reddawg
 UbixOS v1.0

 Revision 1.6  2004/04/13 16:36:34  reddawg
 Changed our copyright, it is all now under a BSD-Style license

 END
 ***/
