/*

	FIPS - the First nondestructive Interactive Partition Splitting program



	Module fat.cpp



	RCS - Header:

	$Header: c:/daten/fips/source/main/RCS/fat.cpp 1.4 1995/01/19 00:00:51 schaefer Exp schaefer $



	Copyright (C) 1993 Arno Schaefer



	This program is free software; you can redistribute it and/or modify

	it under the terms of the GNU General Public License as published by

	the Free Software Foundation; either version 2 of the License, or

	(at your option) any later version.



	This program is distributed in the hope that it will be useful,

	but WITHOUT ANY WARRANTY; without even the implied warranty of

	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

	GNU General Public License for more details.



	You should have received a copy of the GNU General Public License

	along with this program; if not, write to the Free Software

	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.





	Report problems and direct all questions to:



	schaefer@rbg.informatik.th-darmstadt.de

*/



#include <stdlib.h>



#include "logdr_st.h"

#include "global.h"

#include "fat.h"

#include "input.h"





fat::fat (class logical_drive *logical_drive,int number)

{

	fat::logical_drive = logical_drive;

	fat::number = number;

	buffer = new sector;

	start_sector = (number == 1) ? logical_drive->info().start_fat1 : logical_drive->info().start_fat2;

	sector_in_buffer = -1;

}





dword fat16::next_cluster (dword cluster_number)

{

	dword sector = cluster_number / 256;

	int offset = (cluster_number % 256) * 2;



	if (sector != sector_in_buffer)

	{

		read_sector (sector);

	}



	return ((dword) buffer->data[offset] | ((dword) buffer->data[offset + 1] << 8));

}





void fat::read_sector (dword sector)

{

	if (logical_drive->read_sector (sector + start_sector,buffer))

		if (number == 1)

			error ("Error reading FAT 1");

		else

			error ("Error reading FAT 2");



	sector_in_buffer = sector;

}





void fat16::check_against (class fat16 *fat2)

{

	printx ("Checking FAT ... ");



	for (int i=0;i<logical_drive->bpb().sectors_per_fat;i++)

	{

		read_sector (i);

		fat2->read_sector (i);



		for (int j=0;j<512;j++) if (buffer->data[j] != fat2->buffer->data[j])

			error ("FAT copies differ: FAT 1 -> %02Xh, FAT 2 -> %02Xh in sector %u, byte %u",buffer->data[j],fat2->buffer->data[j],i,j);



		if (i == 0)

		{

			if (buffer->data[0] != 0xf8)

			{

				warning (false, "Wrong media descriptor byte in FAT: %02Xh",buffer->data[0]);



				printx ("Continue (y/n)? ");

				if (ask_yes_no () == 'n') exit (-1);

			}



			if ((buffer->data[1] != 0xff) || (buffer->data[2] != 0xff) || (buffer->data[3] != 0xff))

				warning (true, "Wrong FAT entries 1 & 2: %02X %02X %02X %02X",buffer->data[0],buffer->data[1],buffer->data[2],buffer->data[3]);

		}

	}

	printx ("OK\n");

}





void fat16::check_empty (dword new_start_sector)

{

	dword first_cluster = (new_start_sector - logical_drive->info().start_data) / logical_drive->bpb().sectors_per_cluster + 2;



	dword last_cluster = logical_drive->info().no_of_clusters + 1;



	if (last_cluster > ((dword) 256 * logical_drive->bpb().sectors_per_fat - 1)) last_cluster = (dword) 256 * logical_drive->bpb().sectors_per_fat - 1;



	printx ("First Cluster: %lu\nLast Cluster: %lu\n\n",first_cluster,last_cluster);

	printx ("Testing if empty ... ");



	for (dword i=first_cluster;i <= last_cluster;i++)

	{

		dword fat_entry = next_cluster (i);



		if (fat_entry != 0) if (fat_entry != 0xfff7)

		{

			if (fat_entry == 0xffff)

			{

				error ("New partition not empty: cluster %lu ( FAT entry: <EOF> )",i);

			}

			else

			{

				error ("New partition not empty: cluster %lu ( FAT entry: %lu )",i,fat_entry);

			}

		}

	}

	

	printx ("OK\n");

}





dword fat16::min_free_cluster (void)

{

	dword first_cluster = 2;



	dword last_cluster = logical_drive->info().no_of_clusters + 1;



	if (last_cluster > ((dword) 256 * logical_drive->bpb().sectors_per_fat - 1)) last_cluster = (dword) 256 * logical_drive->bpb().sectors_per_fat - 1;



	printx ("Searching for free space ... ");



	dword i;



	for (i=last_cluster;i >= first_cluster;i--)

	{

		dword fat_entry = next_cluster (i);



		if (fat_entry != 0) if (fat_entry != 0xfff7)

		{

			i++;

			break;

		}

	}

	printx ("OK\n\n");

	return (i);

}