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Make use of Microcycle helpers where relevant.

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None of these existed when the Macintosh was first added to this emulator.
This commit is contained in:
Thomas Harte 2022-06-03 15:33:31 -04:00
parent 74e96b881c
commit 3d059cb751
1 changed files with 17 additions and 39 deletions
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56
Machines/Apple/Macintosh/Macintosh.cpp
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@ -204,6 +204,10 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
auto address = cycle.host_endian_byte_address();
// Everything above E0 0000 is signalled as being on the peripheral bus.
//
// This will also act to autovector interrupts, since an interrupt acknowledge
// cycle posts an address with all the higher-order bits set, and VPA doubles
// as the input to request an autovector.
mc68000_.set_is_peripheral_address(address >= 0xe0'0000);
// All code below deals only with reads and writes — cycles in which a
@ -235,18 +239,16 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
// VIA accesses are via address 0xefe1fe + register*512,
// which at word precision is 0x77f0ff + register*256.
if(cycle.operation & Microcycle::Read) {
cycle.value->b = via_.read(register_address);
if(cycle.operation & Microcycle::SelectWord) cycle.value->w |= 0xff00;
cycle.set_value8_high(via_.read(register_address));
} else {
via_.write(register_address, cycle.value->b);
via_.write(register_address, cycle.value8_high());
}
}
} return delay;
case BusDevice::PhaseRead: {
if(cycle.operation & Microcycle::Read) {
cycle.value->b = phase_ & 7;
if(cycle.operation & Microcycle::SelectWord) cycle.value->w |= 0xff00;
cycle.set_value8_low(phase_ & 7);
}
} return delay;
@ -256,10 +258,9 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
// The IWM; this is a purely polled device, so can be run on demand.
if(cycle.operation & Microcycle::Read) {
cycle.value->b = iwm_->read(register_address);
if(cycle.operation & Microcycle::SelectWord) cycle.value->w |= 0xff00;
cycle.set_value8_low(iwm_->read(register_address));
} else {
iwm_->write(register_address, cycle.value->b);
iwm_->write(register_address, cycle.value8_low());
}
} else {
fill_unmapped(cycle);
@ -276,22 +277,12 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
if(cycle.operation & Microcycle::Read) {
scsi_.write(register_address, 0xff, dma_acknowledge);
} else {
if(cycle.operation & Microcycle::SelectWord) {
scsi_.write(register_address, cycle.value->w >> 8, dma_acknowledge);
} else {
scsi_.write(register_address, cycle.value->b, dma_acknowledge);
}
scsi_.write(register_address, cycle.value8_high());
}
} else {
// Even access => this is a read.
if(cycle.operation & Microcycle::Read) {
const auto result = scsi_.read(register_address, dma_acknowledge);
if(cycle.operation & Microcycle::SelectWord) {
// Data is loaded on the top part of the bus only.
cycle.value->w = uint16_t((result << 8) | 0xff);
} else {
cycle.value->b = result;
}
cycle.set_value8_high(scsi_.read(register_address, dma_acknowledge));
}
}
} return delay;
@ -306,12 +297,12 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
scc_.reset();
if(cycle.operation & Microcycle::Read) {
cycle.value->b = 0xff;
cycle.set_value16(0xffff);
}
} else {
const auto read = scc_.read(int(address >> 1));
if(cycle.operation & Microcycle::Read) {
cycle.value->b = read;
cycle.set_value8_high(read);
}
}
}
@ -322,6 +313,8 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
if(cycle.operation & Microcycle::SelectWord) {
adjust_phase();
} else {
// This is definitely a byte access; either it's to an odd address, in which
// case it will reach the SCC, or it isn't, in which case it won't.
if(*cycle.address & 1) {
if(cycle.operation & Microcycle::Read) {
scc_.write(int(address >> 1), 0xff);
@ -365,23 +358,8 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
}
// If control has fallen through to here, the access is either a read from ROM, or a read or write to RAM.
switch(cycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
default:
break;
case Microcycle::SelectWord | Microcycle::Read:
cycle.value->w = *reinterpret_cast<uint16_t *>(&memory_base[address]);
break;
case Microcycle::SelectByte | Microcycle::Read:
cycle.value->b = memory_base[address];
break;
case Microcycle::SelectWord:
*reinterpret_cast<uint16_t *>(&memory_base[address]) = cycle.value->w;
break;
case Microcycle::SelectByte:
memory_base[address] = cycle.value->b;
break;
}
// Potential writes to ROM and all hardware accesses have already been weeded out.
cycle.apply(&memory_base[address]);
return delay;
}