unit DiskIO;

interface

type
 HFile = word;

const
 OF_READ=01;
 OF_WRITE=02;
 OF_READWRITE=03;
 OF_CREATE=04;

function OpenFile(lpFileName:pointer;uStyle:byte):HFile;
procedure CloseHandle(TheFile:HFile);

procedure ReadFile(TheFile:HFile;var Buffer;Size:integer);
procedure WriteFile(TheFile:HFile;const Buffer;Size:integer);

procedure RString(TheFile:HFile;var Para:string);
procedure WString(TheFile:HFile;Para:string);

implementation

{******************** Open/Close ************************}
function OpenFile(lpFileName:pointer;uStyle:byte):HFile; assembler;
asm
 mov ah,3dh
 mov al,uStyle
 cmp al,OF_CREATE
 jne @OFi1
 mov ah,3ch
 mov cx,00
@OFi1:
 dec al
 mov dx,word ptr lpFileName
 int 21h
end;

procedure CloseHandle(TheFile:HFile); assembler;
asm
 mov ah,3eh
 mov bx,TheFile
 int 21h
end;

{***************** Read/Write Data **********************}
procedure ReadFile(TheFile:HFile;var Buffer;Size:integer); assembler;
asm
 mov ah,3fh
 mov bx,TheFile
 mov cx,Size
 mov dx,word ptr Buffer
 int 21h
end;

procedure WriteFile(TheFile:HFile;const Buffer;Size:integer); assembler;
asm
 mov ah,40h
 mov bx,TheFile
 mov cx,Size
 mov dx,word ptr Buffer
 int 21h
end;

{**************** Read/Write Strings ********************}
procedure RString(TheFile:HFile;var Para:string);
assembler;
asm
 push TheFile
 push word ptr Para+2
 push word ptr Para
 push 01
 call ReadFile
 push TheFile
 mov  si,word ptr Para
 mov  ah,00
 mov al,[si]
 inc si
 push word ptr Para + 2
 push si
 push ax
 call ReadFile
end;

procedure WString(TheFile:HFile;Para:string); assembler;
asm
 push TheFile
 push word ptr Para + 2
 mov  si,word ptr Para
 push si
 mov  ah,00
 mov  al,[si]
 inc  ax
 push ax
 call WriteFile
end;

end.