with Ada.Text_IO; use Ada.Text_IO;
with Ada.Sequential_IO;
with Ada.Command_Line; use Ada.Command_Line;

procedure sillymachine is
  type Byte is mod 256;
  package Bin_IO is new Ada.Sequential_IO (Byte);
  type ByteArr is array (Integer range <>) of Byte;

  F : Bin_IO.File_Type;
  FileName : String (1 .. 255);
  FileNameLength : Integer := 0;
  ValidHeader : ByteArr (0 .. 15);
  Arr : ByteArr (0 .. 15);
  I : Integer := 0;
  Value : Byte;

begin
  
  ValidHeader (0) := 6;
  ValidHeader (1) := 148;
  ValidHeader (2) := 32;
  ValidHeader (3) := 118;
  ValidHeader (4) := 101;
  ValidHeader (5) := 114;
  ValidHeader (6) := 121;
  ValidHeader (7) := 95;
  ValidHeader (8) := 115;
  ValidHeader (9) := 105;
  ValidHeader (10) := 108;
  ValidHeader (11) := 108;
  ValidHeader (12) := 121;
  ValidHeader (13) := 0;
  ValidHeader (14) := 0;
  ValidHeader (15) := 0;

  if Argument_Count = 0 then
    New_Line(1);
    Put_Line("Usage: sillymachine <sm binary file>");
    New_Line(1);
    goto THE_END;
  end if;
  
  FileNameLength := Argument (1)'Length;
  FileName(1 .. FileNameLength) := Argument (1);

  Bin_IO.Open(F, Bin_IO.In_File, FileName);
  while not Bin_IO.End_Of_File (F) loop
    Bin_IO.Read(F, Value);
    
    if ValidHeader (I) = Value then
      Value := Value; -- useless line so compiler does not complain
    else
      New_Line(1);
      Put_Line("Error: Please use a valid sm binary file");
      New_Line(1);
      goto THE_END;
    end if;
    I := I + 1;

  end loop;
  Put_Line("Header passed");

<< THE_END >>
end sillymachine;