/*
       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:

       [email protected]
*/

#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);
}


dword fat32::next_cluster (dword cluster_number)
{
       dword sector = cluster_number / 128;
       int offset = (cluster_number % 128) * 4;

       if (sector != sector_in_buffer)
       {
               read_sector (sector);
       }

       return ((dword) buffer->data[offset]) | ((dword) buffer->data[offset + 1] << 8) |
                ((dword) buffer->data[offset + 2] << 16) | ((dword) buffer->data[offset + 3] << 24);
}

void fat32::check_against (class fat32 *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);
                       }
               }
       }
       printx ("OK\n");
}


void fat32::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) 128 * logical_drive->bpb().sectors_per_fat - 1)) last_cluster = (dword) 128 * 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 != 0xffffff7L)
               {
                       if (fat_entry == 0xfffffffL || fat_entry == 0xffffffffL)
                       {
                               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 fat32::min_free_cluster (void)
{
       dword first_cluster = 2;

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

       if (last_cluster > ((dword) 128 * logical_drive->bpb().sectors_per_fat - 1)) last_cluster = (dword) 128 * 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 != 0xffffff7L)
               {
                       i++;
                       break;
               }
       }
       printx ("OK\n\n");
       return (i);
}

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