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# getfreepage.c

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    00001 /*****************************************************************************************
    00002  Copyright (c) 2002 The UbixOS Project
    00003  All rights reserved.
    00004
    00005 Redistribution and use in source and binary forms, with or without modification, are
    00006 permitted provided that the following conditions are met:
    00007
    00008 Redistributions of source code must retain the above copyright notice, this list of
    00009 conditions, the following disclaimer and the list of authors.  Redistributions in binary
    00010 form must reproduce the above copyright notice, this list of conditions, the following
    00011 disclaimer and the list of authors in the documentation and/or other materials provided
    00012 with the distribution. Neither the name of the UbixOS Project nor the names of its
    00013 contributors may be used to endorse or promote products derived from this software
    00014 without specific prior written permission.
    00015
    00016 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
    00017 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
    00018 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
    00019 THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    00020 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
    00021 OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    00022 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
    00023 TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    00024 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    00025
    00026  $Id: getfreepage_8c-source.html 88 2016-01-12 00:11:29Z reddawg $
    00027
    00028 *****************************************************************************************/
    00029
    00030 #include <vmm/vmm.h>
    00031 #include <ubixos/kpanic.h>
    00032 #include <ubixos/spinlock.h>
    00033
    00034 static spinLock_t vmmGFPlock = SPIN_LOCK_INITIALIZER;
    00035
    00036 /************************************************************************
    00037
    00038 Function: void *vmmGetFreePage(pidType pid);
    00039
    00040 Description: Returns A Free Page Mapped To The VM Space
    00041
    00042 Notes:
    00043
    00044 07/30/02 - This Returns A Free Page In The Top 1GB For The Kernel
    00045
    00046 ************************************************************************/
    00047 void           *
    00048 vmmGetFreePage(pidType pid)
    00049 {
    00050   uInt16             x = 0x0, y = 0x0;
    00051   uInt32         *pageTableSrc = 0x0;
    00052
    00053   spinLock(&vmmGFPlock);
    00054
    00055   /* Lets Search For A Free Page */
    00056   for (x = 768; x < 1024; x++) {
    00057
    00058     /* Set Page Table Address */
    00059     pageTableSrc = (uInt32 *) (tablesBaseAddress + (0x1000 * x));
    00060     for (y = 0x0; y < 1024; y++) {
    00061       /* Loop Through The Page Table Find An UnAllocated Page */
    00062       if ((uInt32) pageTableSrc[y] == (uInt32) 0x0) {
    00063         /* Map A Physical Page To The Virtual Page */
    00064         if ((vmm_remapPage(vmmFindFreePage(pid), ((x * 0x400000) + (y * 0x1000)),KERNEL_PAGE_DEFAULT)) == 0x0)
    00065           kpanic("vmmRemapPage: vmmGetFreePage\n");
    00066         /* Clear This Page So No Garbage Is There */
    00067         vmmClearVirtualPage((uInt32) ((x * 0x400000) + (y * 0x1000)));
    00068         /* Return The Address Of The Newly Allocate Page */
    00069         spinUnlock(&vmmGFPlock);
    00070         return ((void *)((x * 0x400000) + (y * 0x1000)));
    00071       }
    00072     }
    00073   }
    00074   /* If No Free Page Was Found Return NULL */
    00075   spinUnlock(&vmmGFPlock);
    00076   return (0x0);
    00077 }
    00078
    00079 /***
    00080  END
    00081  ***/
    00082