/*-
 * Copyright (c) 2002-2018, 2022 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;
	uint32_t map_from		= 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 */
	keepMapping:

	pdI = PD_INDEX(start_page);

	if( pdI > PD_INDEX( VMM_USER_END ) ) {

		map_from = 0x0;

		kprintf( "Couldn't find enough pages\n" );

		goto doneMapping;

	}

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

		vmm_allocPageTable( pdI, pid );

	}

	pageTable = ( uint32_t * ) ( PT_BASE_ADDR + ( pdI * PAGE_SIZE ) );

	ptI = PT_INDEX( start_page );

	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 );

			map_from = 0x0;

			counter = 0;

			goto keepMapping;

		}

		if( map_from == 0x0 ) {

			map_from = start_page;

		}

	}

	if( counter < count ) {

		//start_page = ( pdI + 1 ) * ( PAGE_SIZE * 1024 );

		start_page += ( ( y - ptI ) * 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 = map_from + ( count * PAGE_SIZE );

	}

	for( counter = 0; counter < count; counter++ ) {

		if( ( vmm_remapPage( ( uint32_t ) vmm_findFreePage( pid ), ( map_from + ( counter * PAGE_SIZE ) ), PAGE_DEFAULT, pid, 0 ) ) == 0x0 ) {

			kpanic( "vmmRemapPage: getFreeVirtualPage-1: (%i)[0x%X]\n", type, map_from + ( counter * PAGE_SIZE ) );

		}

		bzero( ( map_from + ( counter * PAGE_SIZE ) ), PAGE_SIZE );

	}

	doneMapping:

	spinUnlock( &fvpSpinLock );

	return( map_from );

}