1 files changed, 86 insertions, 48 deletions

diff --git a/lib/DATS/writer.dats b/lib/DATS/writer.dats
index 24246a1..92314b7 100644
--- a/lib/DATS/writer.dats
+++ b/lib/DATS/writer.dats
@@ -1,6 +1,7 @@
 #include "share/atspre_staload.hats"
 
 staload "lib/SATS/writer.sats"
+staload "lib/SATS/init.sats"
 
 #define ATS_DYNLOADFLAG 0
 
@@ -8,11 +9,16 @@ staload "lib/SATS/writer.sats"
   #define get_buffer() ((void *) 0xB8000)
 %}
 
+vtypedef buffer = [l : agz] (@[screenChar][N] @ l | ptr l)
+typedef writer_t  = @{position = [a:int | a >= 0 && a < N] int (a), color_code = uint8}
+
 extern fun get_buffer():<> buffer = "mac#"
 extern prfun eat_buffer (pf: buffer): void
-extern fun getref (): [l:addr] vtakeoutptr (writer)
 
-fun color_value(c : color): uint8 = 
+
+fn color_value(c : color):<> uint8 = let
+  extern castfn i2u8 {n: nat} (i: int n):<> uint8 n
+in
   case+ c of 
     | Black() => i2u8 0
     | Blue() => i2u8 1
@@ -30,62 +36,94 @@ fun color_value(c : color): uint8 =
     | Pink() => i2u8 13
     | Yellow() => i2u8 14
     | White() => i2u8 15
+end
 
-fun code_value(foreground: color, background:color): uint8 = 
+fn code_value(foreground: color, background:color):<> uint8 = 
   (color_value(background) << 4) lor color_value(foreground)
 
 local
-var _val: writer 
-
-in
-implement getref () = let
-  extern praxi __assert{l:addr} (ptr: ptr (l)): vtakeout0 (writer@l)
-  prval (pf, fpf) = __assert (addr@(_val))
+  extern fn put_char(c : char, w: &writer_t) :<!wrt> void
+  extern fn _clear_screen(w : &writer_t) :<!wrt> void 
 in
-  (pf, fpf | addr@(_val))
-end
-end
+  implement _clear_screen(w) = let
+    fun loop {n : nat | n < N - 1} .<N-n>. (i : int n, w : &writer_t) :<!wrt> void = 
+      (put_char('\0', w); if (i < N - 2) then loop(i+1,w))
+  in
+    loop(0,w);
+    w.position := 0;
+  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
+  implement put_char (c,w) = let
+    val buf = get_buffer()
+    val pos = w.position
+  in
+    if (c = '\n') then
+      let 
+        val new_pos = (pos /  BUFFER_WIDTH + 1) * BUFFER_WIDTH
+      in
+        if (new_pos < N) then
+          w.position := new_pos
+        else
+          _clear_screen(w)
+      end
+    else (
+      buf.1->[w.position] := @{ ascii_character = c, color_code = w.color_code};
+
+      if (pos < N - 1) then
+        w.position := succ(pos)
       else
-        clear_screen()
-    end
-  else (
-    buf.1->[writer.position] := @{ ascii_character = c, color_code = writer.color_code};
+        _clear_screen(w));
 
-    if (pos < N - 1) then
-      writer.position := succ(pos)
-    else
-      clear_screen());
+    let prval() = eat_buffer buf in () end
+  end
 
-  let prval() = eat_buffer buf in () end
-end
 
+  local
 
-implement put_string (str : string) : void = let
-  val (pf, fpf | p_val) = getref()
-  implement string_foreach$fwork<writer> (c,env) = put_char(c,env)
-  val _ =  string_foreach_env<writer> (g1ofg0(str),!p_val)
-  prval() = fpf(pf)
-in  
-end
+  local
+    // Static variable
+    var _writer : writer_t?
+    prval () = opt_none _writer
+    var writer = empty<writer_t>(_writer)
+  in
+    val writer_ref = ref_make_viewptr{enablable writer_t} (view@writer | addr@writer)
+  end
+
+  in
+
+    implement put_string (str : string) : void = let
+      val (vbox pf | p) = ref_get_viewptr(writer_ref)
+      implement string_foreach$fwork<writer_t> (c,env) = put_char(c,env)
+    in  
+      if p->enabled then let
+          prval () = opt_unsome p->obj 
+          val _ = $effmask_ref(string_foreach_env<writer_t> (g1ofg0(str),p->obj))
+          prval () = opt_some p->obj
+        in
+        end
+    end
+
+    implement clear_screen() : void = let
+      val (vbox pf | p) = ref_get_viewptr(writer_ref)
+    in
+      if p->enabled then 
+        let
+          prval () = opt_unsome p->obj
+          val () = _clear_screen(p->obj)
+          prval () = opt_some p->obj
+        in
+        end
+      else
+        let
+          prval () = opt_unnone p->obj
+          val () = p->obj := @{position = 0, color_code = code_value(White,Black)}
+          val () = p->enabled := true
+          val () = _clear_screen(p->obj)
+          prval () = opt_some p->obj
+        in
+        end
+    end
+
+  end
 
-implement clear_screen() : void = let
-  val (pf, fpf | p_val) = getref()
-  fun loop {n : nat | n < N - 1} .<N-n>. (i : int n, wr : &writer) : void = 
-    (put_char('\0', wr); if (i < N - 2) then loop(i+1,wr))
-  val () = !p_val := @{position = 0, color_code = code_value(White,Black)}
-in
-  loop(0,!p_val);
-  !p_val.position := 0;
-  let prval() = fpf(pf) in () end
 end