#include "share/atspre_staload.hats"

staload "kernel/writer.sats"

%{^
  #define get_buffer() ((void *) 0xB8000)
%}

extern fun get_buffer():<> buffer = "mac#"
extern prfun eat_buffer (pf: buffer): void

staload WRITER = {
  staload "kernel/writer.sats"
  extern fun getref (): [l:addr] vtakeoutptr (writer)

  fun color_value(c : color): uint8 = 
    case+ c of 
      | Black() => i2u8 0
      | Blue() => i2u8 1
      | Green() => i2u8 2
      | Cyan() => i2u8 3
      | Red() => i2u8 4
      | Magenta() => i2u8 5
      | Brown() => i2u8 6
      | LightGray() => i2u8 7
      | DarkGray() => i2u8 8
      | LightBlue() => i2u8 9
      | LightGreen() => i2u8 10
      | LightCyan() => i2u8 11
      | LightRed() => i2u8 12
      | Pink() => i2u8 13
      | Yellow() => i2u8 14
      | White() => i2u8 15

  fun code_value(foreground: color, background:color): uint8 = 
    (color_value(background) << 4) lor color_value(foreground)

  local

  var _val: writer = @{position = 0, color_code = code_value(White,Black)} : writer
  val p_val = addr@(_val)

  in

  implement getref () = let
    extern praxi __assert{l:addr} (ptr: ptr (l)): vtakeout0 (writer@l)
    prval (pf, fpf) = __assert (p_val)
  in
    (pf, fpf | p_val)
  end
  end
}


fun put_char (c : char, writer: &writer) : void = let
  val buf = get_buffer()
  val pos = writer.position
in
  if (c = '\n') then
    let 
      val new_pos = (pos /  BUFFER_WIDTH + 1) * BUFFER_WIDTH
    in
      if (new_pos < N) then
        writer.position := new_pos
    end
  else (
    buf.1->[writer.position] := @{ ascii_character = c, color_code = writer.color_code};

    if (pos < N - 1) then
      writer.position := succ(pos));

  let prval() = eat_buffer buf in () end
end


implement put_string (str : string) : void = let
  val (pf, fpf | p_val) = $WRITER.getref()
  implement string_foreach$fwork<writer> (c,env) = put_char(c,env)
  val _ =  string_foreach_env<writer> (g1ofg0(str),!p_val)
  prval() = fpf(pf)
in  end