[Qemu-devel] ps2 mouse cleanups/fixes

[Herbert Poetzl]

Hi Folks!

here is a cleanup/fix to the ps2 mouse emulation done 
by qemu: according to the ps2 protocol specification
the dx and dy values are 9 bit 2's complement where 
the most significant bit appears as a sign bit in the
first byte. similar for dz but 4 bit 2's complement 
here with or without sign extension (IM/Explorer)  

best,
Herbert


diff -NurpP qemu-cvs20060522/hw/ps2.c qemu-cvs20060522/hw/ps2.c
--- qemu-cvs20060522/hw/ps2.c   2006-04-12 23:09:07.000000000 +0200
+++ qemu-cvs20060522/hw/ps2.c   2006-05-23 03:30:37.000000000 +0200
@@ -246,44 +247,36 @@ void ps2_keyboard_set_translation(void *
     s->translate = mode;
 }
 
+#define min(a,b) ((a<b)?a:b)
+#define max(a,b) ((a>b)?a:b)
+
 static void ps2_mouse_send_packet(PS2MouseState *s)
 {
     unsigned int b;
     int dx1, dy1, dz1;
 
-    dx1 = s->mouse_dx;
-    dy1 = s->mouse_dy;
-    dz1 = s->mouse_dz;
-    /* XXX: increase range to 8 bits ? */
-    if (dx1 > 127)
-        dx1 = 127;
-    else if (dx1 < -127)
-        dx1 = -127;
-    if (dy1 > 127)
-        dy1 = 127;
-    else if (dy1 < -127)
-        dy1 = -127;
-    b = 0x08 | ((dx1 < 0) << 4) | ((dy1 < 0) << 5) | (s->mouse_buttons & 0x07);
+    dx1 = min(max(s->mouse_dx,-256),255);
+    dy1 = min(max(s->mouse_dy,-256),255);
+    
+    b = (s->mouse_buttons & 0x07) | 0x08 | 
+       ((dx1 & 0x100) >> 4) | ((dy1 & 0x100) >> 3);
+    
     ps2_queue(&s->common, b);
     ps2_queue(&s->common, dx1 & 0xff);
     ps2_queue(&s->common, dy1 & 0xff);
-    /* extra byte for IMPS/2 or IMEX */
+
     switch(s->mouse_type) {
     default:
+       dz1 = s->mouse_dz;
         break;
-    case 3:
-        if (dz1 > 127)
-            dz1 = 127;
-        else if (dz1 < -127)
-                dz1 = -127;
+    case 3: /* Intellimouse */
+        dz1 = min(max(s->mouse_dz,-8),7);
         ps2_queue(&s->common, dz1 & 0xff);
         break;
-    case 4:
-        if (dz1 > 7)
-            dz1 = 7;
-        else if (dz1 < -7)
-            dz1 = -7;
-        b = (dz1 & 0x0f) | ((s->mouse_buttons & 0x18) << 1);
+    case 4: /* Intellimouse Explorer */
+        dz1 = min(max(s->mouse_dz,-8),7);
+        b = (dz1 & 0x08f) | 
+           ((s->mouse_buttons & 0x18) << 1);
         ps2_queue(&s->common, b);
         break;
     }