1 files changed, 57 insertions, 0 deletions
diff --git a/kernel/writer.dats b/kernel/writer.dats
new file mode 100644
index 0000000..7d0383f
--- /dev/null
+++ b/kernel/writer.dats
@@ -0,0 +1,57 @@
+#include "share/atspre_staload.hats"
+
+staload "kernel/writer.sats"
+
+extern castfn i2u8 {n: nat} (i: int n): uint8 n
+
+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)
+
+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 }
+in
+  ()
+end
+
+%{^
+  #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
+
+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)
+  }
+in 
+  output_char(c,writer);
+  let prval () = eat_writer writer in () end
+end
+