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FILEIO.PAS
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FILEIO.PAS
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UNIT FileIO;
{$I-,X+,O-,F-}
INTERFACE
USES Dos; { Exist Function }
TYPE
FileRec = Record
Handle : Word;
LockFile : Boolean;
Mode : Byte;
FilePos : LongInt;
Open : Boolean;
End;
FUNCTION Reset(S:String; VAR F:FileRec; Mode:Byte):Integer;
FUNCTION Rewrite(S:String; VAR F:FileRec; Mode:Byte):Integer;
FUNCTION Close(VAR F:FileRec):Integer;
FUNCTION LockFile(VAR F:FileRec; Start,Stop:LongInt; LockType:Byte):Integer;
FUNCTION Flush(VAR F:FileRec):Integer;
FUNCTION Truncate(VAR F:FileRec):Integer;
FUNCTION BlockRead(VAR F:FileRec; S,O:Word; Bytes:Integer; VAR Read:Integer):Integer;
FUNCTION BlockWrite(VAR F:FileRec; S,O:Word; Bytes:Integer):Integer;
FUNCTION Seek(VAR F:FileRec; Loc:LongInt):Integer;
FUNCTION SeekEof(VAR F:FileRec):Integer;
FUNCTION FileSize(VAR F:FileRec):LongInt;
FUNCTION FilePos(VAR F:FileRec):LongInt;
PROCEDURE SetLock(VAR F:FileRec; Lock:Boolean);
FUNCTION DeleteRec(VAR F:FileRec; RecNum,RecSize:Integer):Boolean;
FUNCTION Erase(F:String):Boolean;
CONST
NoLock = 2;
EntireLock = 2; { 16 or 2 }
DenyWrite = 2; { 48 or 1 }
DenyRead = 2; { 32 }
RandomLock = 2;
Lock = 0;
Unlock = 1;
IMPLEMENTATION
CONST Tries:Integer=0;
TYPE
LongIntArr=Array[1..2] of Word;
FUNCTION Cflag(VAR Regs:Registers):Boolean;
Begin
Cflag:=(Regs.Flags AND 1>0);
End;
Function Exist(Filename:string):boolean;
{returns true if file exists}
var Inf: SearchRec;
begin
FindFirst(Filename,AnyFile,Inf);
Exist := (DOSError = 0);
end; {Func Exist}
FUNCTION Reset(S:String; VAR F:FileRec; Mode:Byte):Integer;
VAR Regs:Registers;
Begin
Reset:=$FF;
If Not Exist(S) then Exit; { Keeps Lans from Locking Up }
F.Handle:=0;
F.LockFile:=(Mode<>NoLock);
F.Mode:=Mode;
F.FilePos:=0;
F.Open:=False;
Repeat
Regs.Ah:=$3D;
Regs.Al:=Mode;
S[Length(S)+1]:=#0;
Regs.Ds:=Seg(S);
Regs.Dx:=Ofs(S)+1;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then Reset:=Regs.Ax else
Begin
F.Handle:=Regs.Ax;
F.Open:=True;
Reset:=0;
End;
End;
FUNCTION Rewrite(S:String; VAR F:FileRec; Mode:Byte):Integer;
VAR Regs:Registers; I:Integer;
Begin
F.Handle:=0;
F.LockFile:=(Mode<>NoLock);
F.Mode:=Mode;
F.FilePos:=0;
F.Open:=False;
Repeat
Regs.Ah:=$3C;
Regs.Cx:=$00;
Regs.Ds:=Seg(S);
Regs.Dx:=Ofs(S)+1;
S[Length(S)+1]:=#0;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then Rewrite:=Regs.Ax else
Begin
F.Handle:=Regs.Ax;
F.Open:=True;
Close(F);
Rewrite:=Reset(S,F,Mode);
End;
End;
FUNCTION Close(VAR F:FileRec):Integer;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
Close:=127;
Exit;
End;
Repeat
Regs.Ah:=$3E;
Regs.Bx:=F.Handle;
Intr($21,Regs);
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
if Cflag(Regs) then Close:=Regs.Ax else
Begin
Close:=0;
F.Open:=False;
End;
End;
FUNCTION LockFile(VAR F:FileRec; Start,Stop:LongInt; LockType:Byte):Integer;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
LockFile:=127;
Exit;
End;
Repeat
Regs.Ah:=$5C;
Regs.Al:=LockType;
Regs.Bx:=F.Handle;
Regs.Cx:=LongIntArr(Start)[1];
Regs.Dx:=LongIntArr(Start)[2];
Regs.Si:=LongIntArr(Stop)[1];
Regs.Di:=LongIntArr(Stop)[2];
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then LockFile:=Regs.Ax else LockFile:=0;
End;
FUNCTION Flush(VAR F:FileRec):Integer;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
Flush:=127;
Exit;
End;
repeat
Regs.Ah:=$68;
Regs.Bx:=F.Handle;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then Flush:=Regs.Ax else Flush:=0;
End;
FUNCTION Truncate(VAR F:FileRec):Integer;
Begin
End;
FUNCTION BlockRead(VAR F:FileRec; S,O:Word; Bytes:Integer; VAR Read:Integer):Integer;
CONST Error:Boolean=False;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
BlockRead:=127;
Exit;
End;
If F.LockFile then LockFile(F,F.FilePos,F.FilePos+Bytes,Lock);
Repeat
Regs.Ah:=$3F;
Regs.Bx:=F.Handle;
Regs.Cx:=Bytes;
Regs.Ds:=S;
Regs.Dx:=O;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If F.LockFile then LockFile(F,F.FilePos,F.FilePos+Bytes,UnLock);
If Error then Exit;
Read:=0;
If Cflag(Regs) then BlockRead:=Regs.Ax else
Begin
Read:=Regs.Ax;
F.FilePos:=F.FilePos+Regs.Ax;
BlockRead:=0;
End;
End;
FUNCTION BlockWrite(VAR F:FileRec; S,O:Word; Bytes:Integer):Integer;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
BlockWrite:=127;
Exit;
End;
If F.LockFile then LockFile(F,F.FilePos,F.FilePos+Bytes,Lock);
Repeat
Regs.Ah:=$40;
Regs.Bx:=F.Handle;
Regs.Cx:=Bytes;
Regs.Ds:=S;
Regs.Dx:=O;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If F.LockFile then LockFile(F,F.FilePos,F.FilePos+Bytes,UnLock);
If Cflag(Regs) then BlockWrite:=Regs.Ax else
Begin
BlockWrite:=0;
F.FilePos:=F.FilePos+Regs.Ax;
End;
End;
FUNCTION Seek(VAR F:FileRec; Loc:LongInt):Integer;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
Seek:=127;
Exit;
End;
Repeat
Regs.Ah:=$42;
Regs.Al:=$00;
Regs.Bx:=F.Handle;
Regs.Cx:=Word(Loc shl 16);
Regs.Dx:=Word(Loc);
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then Seek:=Regs.Ax else
Begin
Seek:=0;
F.FilePos:=(Regs.Dx shl 16) or Regs.Ax;
End;
End;
FUNCTION SeekEof(VAR F:FileRec):Integer;
VAR Regs:Registers;
Begin
If Not F.Open then
Begin
SeekEof:=127;
Exit;
End;
Repeat
Regs.Ah:=$42;
Regs.Al:=$02;
Regs.Bx:=F.Handle;
Regs.Cx:=0;
Regs.Dx:=0;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then SeekEof:=Regs.Ax else
Begin
F.FilePos:=LongInt((Regs.Dx shl 16) or Regs.Ax);
SeekEof:=0;
End;
End;
FUNCTION FileSize(VAR F:FileRec):LongInt;
VAR Loc:LongInt;
Regs:Registers;
Begin
If Not F.Open then
Begin
FileSize:=$FFFFFFFF;
Exit;
End;
Loc:=F.FilePos;
Repeat
Regs.Ah:=$42;
Regs.Al:=$02;
Regs.Bx:=F.Handle;
Regs.Cx:=0;
Regs.Dx:=0;
MsDos(Regs);
Until Not ((Cflag(Regs)) and (Regs.Ax=$05));
If Cflag(Regs) then
Begin
FileSize:=$FFFFFFFF;
Seek(F,Loc);
End else
Begin
FileSize:=LongInt((Regs.Dx shl 16) or Regs.Ax);
Seek(F,Loc);
End;
End;
FUNCTION FilePos(VAR F:FileRec):LongInt;
Begin
FilePos:=F.FilePos;
End;
PROCEDURE SetLock(VAR F:FileRec; Lock:Boolean);
Begin
F.LockFile:=Lock;
End;
FUNCTION DeleteRec(VAR F:FileRec; RecNum,RecSize:Integer):Boolean;
VAR Position:LongInt;
P:Pointer;
L,I:Integer;
Err:Boolean;
Begin
DeleteRec:=False;
If not F.Open then Exit;
Position:=F.FilePos;
GetMem(P,RecSize);
Err:=False;
If Not (RecNum-1=FileSize(F) div RecSize) then
For I:=RecNum to (FileSize(F) div RecSize) do
Begin
If Seek(F,I*RecSize)<>0 then Err:=True;
If BlockRead(F,Seg(P^),Ofs(P^),RecSize,L)<>0 then Err:=True;
If L<>RecSize then Err:=True;
If Seek(F,(I-1)*RecSize)<>0 then Err:=True;
If BlockWrite(F,Seg(P^),Ofs(P^),RecSize)<>0 then Err:=True;
If Err then Exit;
End;
FreeMem(P,RecSize);
If Err then Exit;
If Seek(F,FileSize(F)-RecSize)<>0 then Exit;
If Truncate(F)<>0 then Exit;
If Seek(F,Position)<>0 then Exit;
DeleteRec:=True;
End;
FUNCTION Erase(F:String):Boolean;
VAR Regs:Registers;
Begin
Regs.Ah:=$41;
Regs.Ds:=Seg(F);
Regs.Dx:=Ofs(F)+1;
F[Length(F)+1]:=#0;
Intr($21,Regs);
Erase:=Cflag(Regs);
End;
End.