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Attempts 48/128kb floating bus behaviour.

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This commit is contained in:
Thomas Harte 2021-04-15 21:19:21 -04:00
parent fa18b06dbf
commit ef636da866
1 changed files with 22 additions and 2 deletions
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24
Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp
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@ -321,6 +321,15 @@ template<Model model> class ConcreteMachine:
} }
case PartialMachineCycle::Read: case PartialMachineCycle::Read:
if constexpr (model == Model::SixteenK) {
// Assumption: with nothing mapped above 0x8000 on the 16kb Spectrum,
// read the floating bus.
if(address >= 0x8000) {
*cycle.value = video_->get_floating_value();
break;
}
}
*cycle.value = read_pointers_[address >> 14][address]; *cycle.value = read_pointers_[address >> 14][address];
if constexpr (model >= Model::Plus2a) { if constexpr (model >= Model::Plus2a) {
@ -413,10 +422,13 @@ template<Model model> class ConcreteMachine:
} }
break; break;
case PartialMachineCycle::Input: case PartialMachineCycle::Input: {
bool did_match = false;
*cycle.value = 0xff; *cycle.value = 0xff;
if(!(address&1)) { if(!(address&1)) {
did_match = true;
// Port FE: // Port FE:
// //
// address b8+: mask of keyboard lines to select // address b8+: mask of keyboard lines to select
@ -446,6 +458,8 @@ template<Model model> class ConcreteMachine:
if constexpr (model >= Model::OneTwoEightK) { if constexpr (model >= Model::OneTwoEightK) {
if((address & 0xc002) == 0xc000) { if((address & 0xc002) == 0xc000) {
did_match = true;
// Read from AY register. // Read from AY register.
update_audio(); update_audio();
*cycle.value &= GI::AY38910::Utility::read(ay_); *cycle.value &= GI::AY38910::Utility::read(ay_);
@ -469,7 +483,13 @@ template<Model model> class ConcreteMachine:
break; break;
} }
} }
break;
if constexpr (model < Model::Plus2) {
if(!did_match) {
*cycle.value = video_->get_floating_value();
}
}
} break;
} }
return HalfCycles(0); return HalfCycles(0);