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Slightly clarifies logic.

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This commit is contained in:
Thomas Harte 2020-01-04 21:32:34 -05:00
parent 7b2777ac08
commit e4349f5e05
1 changed files with 6 additions and 7 deletions
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13
Machines/Atari/ST/AtariST.cpp
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@ -348,13 +348,12 @@ class ConcreteMachine:
cycle.set_value8_high(ay_.get_data_output());
ay_.set_control_lines(GI::AY38910::ControlLines(0));
} else {
if(!(address&2)) {
// Select register.
ay_.set_control_lines(GI::AY38910::BC1);
} else {
// Write data to register.
ay_.set_control_lines(GI::AY38910::ControlLines(GI::AY38910::BC2 | GI::AY38910::BDIR));
}
// Net effect here: addresses with bit 1 set write to a register,
// addresses with bit 1 clear select a register.
ay_.set_control_lines(GI::AY38910::ControlLines(
GI::AY38910::BC2 | GI::AY38910::BDIR
| ((address&2) ? 0 : GI::AY38910::BC1)
));
ay_.set_data_input(cycle.value8_high());
ay_.set_control_lines(GI::AY38910::ControlLines(0));
}