Bug #45385 related to keyboard and probably wineserver - where to start the search

[Alex Henrie]

On Wed, Jun 27, 2018 at 11:24 AM John Found <johnfound at asm32.info> wrote:
>
> While reading the code in wineX11.drv/keyboard.c I noticed the following fragment from the function X11DRV_KeymapNotify:
>
>     for (vkey = VK_LSHIFT; vkey <= VK_RMENU; vkey++)
>     {
>         int m = vkey - VK_LSHIFT;
> >>>     if (modifiers[m].vkey && !(keystate[vkey] & 0x80) != !modifiers[m].pressed)
>         {
>             TRACE( "Adjusting state for vkey %#.2x. State before %#.2x\n",
>                    modifiers[m].vkey, keystate[vkey]);
>
>             update_key_state( keystate, vkey, modifiers[m].pressed );
>             changed = TRUE;
>         }
>     }
>
> Can someone explain what the condition pointed by >>> is doing? (Unfortunately, my C skills are pretty low...)
>
> Why not simply "(modifiers[m].vkey && (keystate[vkey] & 0x80) != modifiers[m].pressed)"?

I don't immediately know what this if statement is for, but I can tell
you that the ! operator converts a value of zero to 1 and a nonzero
value to 0. So, if keystate[vkey] & 0x80 is 0 then
modifiers[m].pressed must be nonzero and vice versa.

-Alex