When the user moves the mouse and moves the scroll wheel at the same time, the mouse cursor's movement becomes erratic in Windows 3.1. With this patch if the mouse is in ps/2 mode and the scroll wheel is used, the command queue is reset. This does not fix the erratic mouse problem in Windows NT 4.0.

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>
---
 hw/input/ps2.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/input/ps2.c b/hw/input/ps2.c
index fdfcadf9a1..bb9ebfa5a9 100644
--- a/hw/input/ps2.c
+++ b/hw/input/ps2.c
@@ -685,8 +685,17 @@ static int ps2_mouse_send_packet(PS2MouseState *s)
     /* update deltas */
     s->mouse_dx -= dx1;
     s->mouse_dy -= dy1;
-    s->mouse_dz -= dz1;
+    /*
+     * This prevents the mouse from going crazy in Windows that doesn't support
+     * the Microsoft Intellimouse standard.
+     */
+    if (s->mouse_type == 0 && s->mouse_dz != 0) {
+        s->mouse_dz = 0;
+        ps2_reset_queue(&s->common);
+        return 1;
+    }
 
+    s->mouse_dz -= dz1;
     return 1;
 }
 
-- 
2.14.3 (Apple Git-98)

On Sun, Aug 19, 2018 at 12:35:09AM -0400, John Arbuckle wrote:
> When the user moves the mouse and moves the scroll wheel at the same
> time, the mouse cursor's movement becomes erratic in Windows 3.1. With
> this patch if the mouse is in ps/2 mode and the scroll wheel is used,
> the command queue is reset. This does not fix the erratic mouse
> problem in Windows NT 4.0.

I don't think we need to reset the queue.  Just ignoring the z axis
value for type 0 should do.  Can you try this?

--- a/hw/input/ps2.c
+++ b/hw/input/ps2.c
@@ -661,6 +661,8 @@ static int ps2_mouse_send_packet(PS2MouseState *s)
     /* extra byte for IMPS/2 or IMEX */
     switch(s->mouse_type) {
     default:
+        s->mouse_dz = 0;
+        dz1 = 0;
         break;
     case 3:
         if (dz1 > 127)

cheers,
  Gerd

> On Aug 20, 2018, at 1:24 AM, Gerd Hoffmann <kraxel@redhat.com> wrote:
> 
> On Sun, Aug 19, 2018 at 12:35:09AM -0400, John Arbuckle wrote:
>> When the user moves the mouse and moves the scroll wheel at the same
>> time, the mouse cursor's movement becomes erratic in Windows 3.1. With
>> this patch if the mouse is in ps/2 mode and the scroll wheel is used,
>> the command queue is reset. This does not fix the erratic mouse
>> problem in Windows NT 4.0.
> 
> I don't think we need to reset the queue.  Just ignoring the z axis
> value for type 0 should do.  Can you try this?
> 
> --- a/hw/input/ps2.c
> +++ b/hw/input/ps2.c
> @@ -661,6 +661,8 @@ static int ps2_mouse_send_packet(PS2MouseState *s)
>     /* extra byte for IMPS/2 or IMEX */
>     switch(s->mouse_type) {
>     default:
> +        s->mouse_dz = 0;
> +        dz1 = 0;
>         break;
>     case 3:
>         if (dz1 > 127)
> 
> cheers,
>  Gerd
> 

Sorry it did not fix the problem.

https://winworldpc.com/product/windows-3/31
In case you or anyone else wishes to reproduce this problem, the link to the Windows 3.1 installer is above.

Thank you.