/*-
 * 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 <lib/kprintf.h>

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

 Function: void vmm_unmapPage(uInt32 pageAddr,int flags);
 Description: This Function Will Unmap A Page From The Kernel VM Space
 The Flags Variable Decides If Its To Free The Page Or Not
 A Flag Of 0 Will Free It And A Flag Of 1 Will Keep It
 Notes:

 07/30/02 - I Have Decided That This Should Free The Physical Page There
 Is No Reason To Keep It Marked As Not Available

 07/30/02 - Ok A Found A Reason To Keep It Marked As Available I Admit
 Even I Am Not Perfect Ok The Case Where You Wouldn't Want To
 Free It Would Be On Something Like Where I Allocated A Page
 To Create A New Virtual Space So Now It Has A Flag

 ************************************************************************/
void vmm_unmapPage( uint32_t pageAddr, unmapFlags_t flags ) {

	int pageDirectoryIndex	= 0;
	int pageTableIndex		= 0;

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

	pageDirectory = ( uint32_t * ) PD_BASE_ADDR;

	//	Get The Index To The Page Directory
	pageDirectoryIndex = ( pageAddr >> 22 );

	if( ( pageDirectory[pageDirectoryIndex] & PAGE_PRESENT ) != PAGE_PRESENT ) {

		kprintf( "Attemped to unmap non-mapped page: [0x%X]", pageAddr );

		return;

	}

	//	Calculate The Page Table Index
	pageTableIndex = ( ( pageAddr >> 12 ) & 0x3FF );

	//	Set pageTable To The Virtual Address Of Table
	pageTable = ( uint32_t * ) ( PT_BASE_ADDR + ( 0x1000 * pageDirectoryIndex ) );

	//	Free The Physical Page If Flags Is 0
	if( flags == 0 )
		freePage( ( uint32_t ) ( pageTable[pageTableIndex] & 0xFFFFF000 ) );

	//	Unmap The Page
	pageTable[pageTableIndex] = 0x0;

	//	Rehash The Page Directory
	asm volatile(
			"movl %cr3,%eax\n"
			"movl %eax,%cr3\n"
	);

	//	Return

	return;

}

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

 Function: void vmm_unmapPages(uInt32 pageAddr,int flags);
 Description: This Function Will Unmap A Page From The Kernel VM Space
 The Flags Variable Decides If Its To Free The Page Or Not
 A Flag Of 0 Will Free It And A Flag Of 1 Will Keep It
 Notes:

 07/30/02 - I Have Decided That This Should Free The Physical Page There
 Is No Reason To Keep It Marked As Not Available

 07/30/02 - Ok A Found A Reason To Keep It Marked As Available I Admit
 Even I Am Not Perfect Ok The Case Where You Wouldn't Want To
 Free It Would Be On Something Like Where I Allocated A Page
 To Create A New Virtual Space So Now It Has A Flag

 ************************************************************************/
void vmm_unmapPages( void *ptr, uint32_t size, unmapFlags_t flags ) {

	uInt32 baseAddr		= ( uInt32 ) ptr & 0xFFFFF000;
	uInt32 dI 			= 0x0;
	uInt32 tI			= 0x0;
	uInt32 y 			= 0x0;
	uInt32 *pageTable	= 0x0;

	dI			= ( baseAddr / ( 1024 * 4096 ) );
	tI			= ( ( baseAddr - ( dI * ( 1024 * 4096 ) ) ) / 4096 );
	pageTable	= ( uInt32 * ) ( PT_BASE_ADDR + ( 4096 * dI ) );

	for( y = tI; y < ( tI + ( ( size + 4095 ) / 4096 ) ); y++ ) {

		pageTable[y] = 0x0;

	}

	return;

}