[Qemu-devel] qemu kbd emulation

["Rafał Cygnarowski" <zswi@pers.pl>]

Hi!

I wanted to correct qemu emulation of keyboard under DOS as 
guest OS, so I started with simple pascal program to check 
what happen on guest DOS (and DOS) when I press up/down/left/right 
keys.

The program was:

-- BEGIN test.pas --
program time; {$M 2048,0,0}
uses crt, dos;
var OldKeyInt : procedure;

procedure NewKeyInt; interrupt;
begin
        write(Port[$60]); write(' ')
        inline($9c); OldKeyInt;
end;

begin
        getintvec($9, addr(OldKeyInt));
        setintvec($9, @NewKeyInt);
        keep(0);
end.
-- END test.pas --

and it look that qemu does not generate some codes before 
pressing and after releasing arrow keys. For example pressing 
up key on qemu looks like:

224 72 224 200

while without emulation it looks:

224 42 224 72 224 200 224 170.

It's true only for single keystrokes, but good for the 
beginning.

So I tried to patch qemu for this and created following patch:

-- BEGIN sdl.patch --
--- sdl.c.old   2006-05-03 20:32:58.000000000 +0000
+++ sdl.c       2006-06-28 07:26:14.000000000 +0000
@@ -254,14 +254,34 @@
         kbd_put_keycode(keycode);
         kbd_put_keycode(keycode | 0x80);
         return;
+    case 0xc8: /* up */
+    case 0xd0: /* down */
+    case 0xcd: /* right */
+    case 0xcb: /* left */
+       if (ev->type != SDL_KEYUP) {
+           kbd_put_keycode(e0);
+           kbd_put_keycode(2a);
+       }
+       break;
     }
-
+
     /* now send the key code */
     if (keycode & 0x80)
         kbd_put_keycode(0xe0);
-    if (ev->type == SDL_KEYUP)
-        kbd_put_keycode(keycode | 0x80);
-    else
+
+    if (ev->type == SDL_KEYUP) {
+       kbd_put_keycode(keycode | 0x80);
+
+       switch(keycode) {
+        case 0xc8: /* up */
+       case 0xd0: /* down */
+        case 0xcd: /* right */
+       case 0xcb: /* left */
+           kbd_put_keycode(0xe0);
+           kbd_put_keycode(0xaa);
+       break;
+       }
+    } else
         kbd_put_keycode(keycode & 0x7f);
 }
-- END sdl.patch --

Unfortunatelly results of this patch completely suprised me. After this patch 
my test program produces results witch are impossible to produce in normal 
situation. Example output for UP key was:

224 224 72 88224 224 170.

What's wrong with this patch? What I'm doing wrong?

Regards,
-- 
Rafał Cygnarowski
rafi@pers.pl