adbkeyboard: Improve register 2 emulation - #225
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We were defaulting the contents of register 2 to zeros, but that actually means an active state (modifier key is being held down and/or an LED is on, see Table 8-11 in "Guide to Macintosh Family Hardware (2nd Edition, 1990)"). We should default to 1, and also actually track and report modifier key state. This affected the BeOS boot chooser - it gets modifiers from register 2, and the 0 value made it think that all modifiers were being held. In turn that would make it bring up the "choose device" screen, instead of automatically continuing with the previously-selected one. Classic Mac OS was not affected (e.g. for hold down shift to disable extensions) because it consumes key updates from register 0 and maintains its own modifier state.
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We were defaulting the contents of register 2 to zeros, but that actually means an active state (modifier key is being held down and/or an LED is on, see Table 8-11 in "Guide to Macintosh Family Hardware (2nd Edition, 1990)"). We should default to 1, and also actually track and report modifier key state.
This affected the BeOS boot chooser - it gets modifiers from register 2, and the 0 value made it think that all modifiers were being held. In turn that would make it bring up the "choose device" screen, instead of automatically continuing with the previously-selected one.
Classic Mac OS was not affected (e.g. for hold down shift to disable extensions) because it consumes key updates from register 0 and maintains its own modifier state.