--  Usage: several_sizes <big_file>
--  Produces <size>.tmp files that are partial copies of <big_file>, with different sizes.
--  These files can be compressed for testing.

with Ada.Text_IO, Ada.Integer_Text_IO;
with Ada.Streams.Stream_IO;             use Ada.Streams.Stream_IO;
with Ada.Command_Line;                  use Ada.Command_Line;
with Interfaces;                        use Interfaces;

procedure Several_sizes is

  f_in, f_out : Ada.Streams.Stream_IO.File_Type;

  type Buffer is array (Natural range <>) of Unsigned_8;

  procedure Read (b : out Buffer; last_read : out Natural) is
    use Ada.Streams;
    Last : Stream_Element_Offset;
    SE_Buffer : Stream_Element_Array (1 .. b'Length);
    for SE_Buffer'Address use b'Address;
    pragma Import (Ada, SE_Buffer);
  begin
    Read (Stream (f_in).all, SE_Buffer, Last);
    last_read := b'First + Natural (Last) - 1;
  end Read;

  procedure Write (b : in Buffer) is
    use Ada.Streams;
    SE_Buffer : Stream_Element_Array (1 .. b'Length);
    for SE_Buffer'Address use b'Address;
    pragma Import (Ada, SE_Buffer);
  begin
    Write (Stream (f_out).all, SE_Buffer);
  end Write;

  ----------
  -- Test --
  ----------

  function name return String is
  begin
    return Argument (1);
  end name;

  procedure Test (limit : Natural) is
    b : Buffer (1 .. 1024);
    l, rest : Natural;
    s : String (1 .. 15);
  begin
    Ada.Integer_Text_IO.Put (s, limit + 1_000_000_000);
    rest := limit;
    Open (f_in, In_File, name);
    Create (f_out, Out_File, s (7 .. 15) & ".tmp");
    while not End_Of_File (f_in) loop
      Read (b, l);
      if rest < l then
        Write (b (1 .. rest));
        exit;
      end if;
      Write (b (1 .. l));
      rest := rest - l;
    end loop;
    Close (f_out);
    Close (f_in);
  end Test;

  use Ada.Text_IO;

  s : Positive;

begin
  if Argument_Count = 0 then
    Put_Line (" Usage: several_sizes <big_file>");
    Put_Line (" Produces <size>.tmp files that are partial copies of <big_file>, with different sizes.");
    return;
  end if;
  --  Tiny files
  for i in 0 .. 126 loop
    Test (i);
  end loop;
  --  Around powers of two (typical LZ sliding window sizes)
  s := 128;
  loop
    for i in -60 .. 60 loop
      Test (s + i);
    end loop;
    s := s * 2;
    exit when s > 300_000;
  end loop;
end Several_sizes;