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Splitting here isn't achieving anything.

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This commit is contained in:
Thomas Harte 2021-04-04 19:52:38 -04:00
parent 1da51bee6c
commit f26bf4b9e4
1 changed files with 5 additions and 14 deletions
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17
Machines/Sinclair/ZXSpectrum/ZXSpectrum.cpp
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@ -185,12 +185,12 @@ template<Model model> class ConcreteMachine:
using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
const uint16_t address = cycle.address ? *cycle.address : 0x0000;
// Apply contention if necessary.
if(
is_contended_[address >> 14] &&
cycle.operation >= PartialMachineCycle::ReadOpcodeStart &&
cycle.operation <= PartialMachineCycle::WriteStart) {
// Apply contention if necessary.
//
// Assumption here: the trigger for the ULA inserting a delay is the falling edge
// of MREQ, which is always half a cycle into a read or write.
//
@ -201,15 +201,9 @@ template<Model model> class ConcreteMachine:
return delay;
}
// TODO: for read/write this should advance only until the rising edge of MREQ, then do
// the read/write, then complete the bus cycle. Only via the 48/128k Spectrum contended
// timings am I now learning what happens with MREQ during extended read/write bus cycles
// (i.e. those longer than 3 cycles)
if(cycle.length > HalfCycles(3)) {
advance(HalfCycles(3));
} else {
// For all other machine cycles, model the action as happening at the end of the machine cycle;
// that means advancing time now.
advance(cycle.length);
}
switch(cycle.operation) {
default: break;
@ -367,9 +361,6 @@ template<Model model> class ConcreteMachine:
break;
}
if(cycle.length > HalfCycles(3)) {
advance(cycle.length - HalfCycles(3));
}
return HalfCycles(0);
}