Simtel MSDOS 1992 December/simtel1292_SIMTEL_1292_Walnut_Creek.iso/msdos/progjorn/pj_7_2.arc/FORMAT.PAS

Pascal/Delphi Source File | 1989-02-28 | 6KB | 249 lines

{ sample code fragments from John Newlin's "Disk Formatting" }

 AddressFieldType = record
                     TrackNum,HeadNum,SectNum,SizeCode : byte;
                    End;
Const
  MaxSectors = 18;
  Disk360Params : array[0..10] of byte =
     ($DF,$02,$25,$02,$09,$2A,$FF,$50,$F6,$0F,$08);

Type
  DiskParameterTableType = Record
                             StepRate, LoadTime, Shutoff,
                             BytesSec, SecTrack, GapLen,
                             DataLen, FGapLen, FillByte,
                             SettleTime,StartTime : byte;
                           End;

Var
  AddressFields : array[1..MaxSectors] of AddressFieldType;
  RAMTable : DiskParameterTableType absolute $0000:$0078;
  regs   : registers;

Begin
  With Regs Do
    Begin
      AH := $18H;                 {set up to call function}
      DL := DriveNum;             {0 = A, 1 = B, etc.}
      CH := NumOfTracks;          {39 or 79 tracks}
      CL := NumOfSectors;         {number of sectors/track}
      Intr($13,Regs);             {call the BIOS}
      if Flags and 1 = 0 the move(mem[ES:DI],RAMTable^,11)
        else move(Disk360Params,RAMTable^,11);
    End;
End;


Procedure LoadParameterTable;
Var
  i : byte;
Begin
  For i := 1 to NumSectors do
    Begin
      AddressFields[i].HeadNum := 0;
      AddressFields[i].SectNum := i;
      AddressFileds[i].SizeCode[i] := 2;
      AddressFields[i + NumSectors].HeadNum := 1;
      AddressFields[i + NumSectors].SectNum := i;
      AddressFields[i + NumSectors].SizeCode := 2;
    End;
End;

Function FormatTrack(Var Params; drive, track, sectors) : word;
var Regs : Registers;
    i : byte;
Begin
  With Regs Do
    Begin
      ES := seg(params);
      BX := ofs(params);
      AH := $05;
      CH := track;
      DL := drive;
      DH := 0;
      AL := sectors;
      For i := 1 to sectors * 2 do Params[i].TrackNum := track;

      Intr($13,Regs);
      if Flags and 1 <> 0 then
        begin
          FormatTrack := word(AH);
          exit;
        end;
      DH := 1;
      ES := seg(params);
      BX := ofs(params) + (4 * sectors);

      AL := sectors
      AH := 05H;
      Intr($13,Regs);
      if Flags and 1 = 0 then FormatTrack := 0
          else FormatTrack := word(AH);
      End;
End;


{$L BOOTSEC.BIN}

Procedure BootSector; External;

Type
  BootType = Array[0..511] of byte;

Var
  Boot : ^BootType;

Begin
  Boot := @BootSector;
  ......
  ......

Const
  Disk360Boot : Array[1..14] of byte =
   ($02,$01,$00,$02,$70,$00,$D0,$02,$FD,$02,$00,$09,$00,$02);

Function WriteSector(drive,track,side,
                     sector : byte; var buffer) : boolean;
Var
  Regs : registers;
Begin
  With Regs do
    Begin
      AH := $03;
      AL := 1;
      ES := seg(buffer);
      BX := ofs(buffer);
      CH := track;
      CL := sector;
      DH := side;
      DL := drive;
      Intr($13,Regs);
      WriteSector := flags and 1 = 0;
    End;
End;


Var
  Fat : Array[2..3] of BootType;
  i : byte;

Begin
  FillChar(Fat,sizeof(Fat),0);
  Fat[1] := $FD;  Fat[2] := $FF;  Fat[3] := $FF;

For i := 2 to 3 do
  Begin
    if not WriteSector(1,0,0,i,Fat) then;
    if not WriteSector(1,0,0,i+2,Fat) then;
  End;


Begin
  FillChar(Boot,Sizeof(boot),0);
  For i := 6 to 9 do if WriteSector(1,0,0,i,boot) then;
  For i := 1 to 3 do if WriteSector(1,0,1,i,boot) then;
End;

Function VerifyTrack(Drive,Side,Track,Sectors : byte) : boolean;
Var Regs : Registers;
Begin
  With Regs Do
    Begin
      AH := $04;
      AL := Sectors;
CH := Track;
CL := 1;
DH := Side;
DL := Drive;
      Int($13,Regs);
      VerifyTrack := Flags and 1 = 0;
    End;
End;

Function DosSector(Side,Track,BiosSector,SPS : byte) : word;
Begin
  DosSector := word(BiosSector - 1) + word(Side * SPS) +
               word(Track * SPS * 2);
End;

Function DosCluster(DosSector : word) : word;
Begin
  DosCluster := (DosSector div SPC) - CNAdjust;
End;

Function FATOffset(Cluster : word) : word;
Begin
  FATOffset := (Cluster * 3) div 2;
End;

Type
  FATType = Array[1..512] of byte;

Var
  FAT : array[0..4607] of byte;
  FATSector : array[1..9] of FATType absolute FAT;
  BadCount : word;

Procedure MarkFat(ClusterNumber : word);
Var Offset : word;
Begin
  Inc(BadCount);
  Offset := FATOffset(ClusterNumber);
  if odd(ClusterNumber) then
    Begin
      Fat[Offset] := Fat[Offset] or $70;
      Fat[Offset+1] := $FF;
    End
  Else
   Begin
     Fat[Offset] := $F7;
     Fat[Offset+1] := $0F;
  End;
End;

Procedure VerifyDisk(Drive,Tracks,Sectors,SPS,FatLen : byte);
Var Trk,Sector,Side : byte;
    LastCN : word;

Procedure MarkTrack(Drive,Track,Side : byte);
Var Sector : byte
    DosSect,Cluster : word;
Begin
  For Sector := 1 to Sectors do
    Begin
      DosSec := DosSector(Side,Track,Sector,SPS);
      Cluster := DosCluster(DosSec);
      if Cluster <> LastCN then
        Begin
          MarkFat(Cluster);
          LastCN := Cluster;
        End;
    End;
  End;
End;

Begin
  FillChar(Fat,Sizeof(Fat),0);
  BadCount := 0;
  LastCN := 0;
  FAT[0] := $FD;
  FAT[1] := $FF;
  FAT[2] := $FF;
  For Trk := 1 to Tracks do
    Begin
      For Side := 0 to 1 do
        if not VerifyTrack(Drive,Trk,Side,SPS) then
          MarkFat(Drive,Trk,Side);
    End;
  If BadCount > 0 then
    Begin
      For i := 2 to FatLen + 1 do
        Begin
          If WriteSector(Drive,0,0,i,FATSector[i]) then;
          If WriteSecotr(Drive,0,0,i + FatLen,FATSector[i]) then;
        End;
    End;
End;