[hatari-devel] Better interrupts for simultaneous HBL/VBL

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Hello

similar to what I changed for MFP, I added support for the IACK sequence 
during an HBL/VBL exception.
This will fix some rare cases where a second interrupt happens just 
after the same interrupt triggered its exception.

If that second "simultaneous" interrupt's signal happen less than 20 
cycles after the current exception, it should be ignored (because IPL 
will be set twice for this interrupt, before it is cleared at the end of 
the IACK sequence).

A few games/demos rely on this (certainly not on purpose, as this is 
rather bad coding practice) : Super Monaco GP, Super Hang On, Monster 
Business, Europen Demo's Intro, BBC Compil Menu 52.

I tried a few STF programs without any problem, please test it still 
compiles/works on Falcon.

Nicolas