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Merge pull request #419 from TomHarte/ZXLineCounter

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Simplifies the test for resetting the ZX80/81 line counter.
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Thomas Harte 2018-05-01 22:04:39 -04:00 committed by GitHub
commit af0cf0d40a
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1 changed files with 3 additions and 5 deletions
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8
Machines/ZX8081/ZX8081.cpp
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@ -124,14 +124,12 @@ template<bool is_zx81> class ConcreteMachine:
bool is_opcode_read = false;
switch(cycle.operation) {
case CPU::Z80::PartialMachineCycle::Output:
if(!(address & 2)) nmi_is_enabled_ = false;
if(!(address & 1)) nmi_is_enabled_ = is_zx81_;
if(!nmi_is_enabled_) {
// Line counter reset is held low while vsync is active; simulate that lazily by performing
// an instant reset upon the transition from active to inactive.
if(vsync_) line_counter_ = 0;
line_counter_ = 0;
set_vsync(false);
}
if(!(address & 2)) nmi_is_enabled_ = false;
if(!(address & 1)) nmi_is_enabled_ = is_zx81_;
// The below emulates the ZonX AY expansion device.
if(is_zx81) {