Using reference

1 files changed, 21 insertions, 20 deletions

diff --git a/kernel/writer.dats b/kernel/writer.dats
index 7d0383f..9ea10b8 100644
--- a/kernel/writer.dats
+++ b/kernel/writer.dats
@@ -4,6 +4,14 @@ staload "kernel/writer.sats"
 
 extern castfn i2u8 {n: nat} (i: int n): uint8 n
 
+extern fun get_vram():<> [l: agz] (@[screenChar][N] @ l | ptr l) = "mac#"
+
+extern prfun eat_writer (pf: writer): void
+
+%{^
+  #define get_vram() ((void *) 0xB8000 + 1988)
+%}
+
 fun color_value(c : color): uint8 = 
   case+ c of 
     | Black() => i2u8 0
@@ -26,32 +34,25 @@ fun color_value(c : color): uint8 =
 fun code_value(foreground: color, background:color): uint8 = 
   (color_value(background) << 4) lor color_value(foreground)
 
-fun output_char(c : char, writer : !writer) : void = let
-  val p = writer.buffer.1
-  val () = p->[writer.column_position] := @{ ascii_character = c , color_code = writer.color_code }
+fun put_char (c : char, writer: &writer) : void = let
+  val v = writer.buffer.1
+  val pos = writer.position
 in
-  ()
-end
+    v->[writer.position] := @{ ascii_character = c, color_code = writer.color_code};
 
-%{^
-  #define get_vram() ((void *) 0xB8000 + 1988)
-%}
-
-extern fun get_vram():<> [l: addr] (@[screenChar][N] @ l | ptr l) = "mac#"
-
-extern prfun eat_writer (pf: writer): void
-
-extern castfn uint8_of {n: nat} (i: int n): uint8 n
+    if (pos < N - 1) then
+      writer.position := succ(pos)
+end
 
 implement print_char(c : char) : void = let
   val (pf_vram | vram) = get_vram()
-  val writer = @{
-    column_position = i2sz 0,
-    color_code = code_value(Yellow,Black),
-    buffer = (pf_vram | vram)
-  }
+  var writer = @{position = 0, color_code = code_value(Black,Yellow), buffer = (pf_vram | vram)} : writer
 in 
-  output_char(c,writer);
+  put_char(c,writer);
+  put_char(c,writer);
+  put_char(c,writer);
+  put_char(c,writer);
+  put_char(c,writer);
   let prval () = eat_writer writer in () end
 end