6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-12-23 20:29:42 +00:00
Code Issues Projects Releases Wiki Activity

Corrects 68000 address bus during interrupt acknowledge.

Browse Source 
All unused bits should be 1, not 0.
This commit is contained in:
Thomas Harte 2019-08-03 15:38:36 -04:00
parent a07488cf1b
commit 478f2533b5
2 changed files with 12 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
Machines/Apple/Macintosh/Macintosh.cpp
View File

@ -180,7 +180,12 @@ template <Analyser::Static::Macintosh::Target::Model model> class ConcreteMachin
// All code below deals only with reads and writes — cycles in which a
// data select is active. So quit now if this is not the active part of
// a read or write.
if(!cycle.data_select_active()) return delay;
//
// The 68000 uses 6800-style autovectored interrupts, so the mere act of
// having set VPA above deals with those given that the generated address
// for interrupt acknowledge cycles always has all bits set except the
// lowest explicit address lines.
if(!cycle.data_select_active() || (cycle.operation & Microcycle::InterruptAcknowledge)) return delay;
uint16_t *memory_base = nullptr;
switch(memory_map_[word_address >> 18]) {
@ -294,17 +299,10 @@ 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.
// TODO: interrupt acknowledge cycles also end up here, which may suggest the 68000 is loading the address bus
// incorrectly during interrupt acknowledgment cycles. Check.
switch(cycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read | Microcycle::InterruptAcknowledge)) {
switch(cycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
default:
break;
case Microcycle::InterruptAcknowledge | Microcycle::SelectByte:
// The Macintosh uses autovectored interrupts.
mc68000_.set_is_peripheral_address(true);
break;
case Microcycle::SelectWord | Microcycle::Read:
cycle.value->full = memory_base[word_address];
break;

14
Processors/68000/Implementation/68000Implementation.hpp
View File

@ -234,12 +234,6 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
continue;
case ExecutionState::BeginInterrupt:
#ifdef LOG_TRACE
// should_log = true;
if(should_log) {
printf("\n\nInterrupt\n\n");
}
#endif
active_program_ = nullptr;
active_micro_op_ = interrupt_micro_ops_;
execution_state_ = ExecutionState::Executing;
@ -1960,10 +1954,12 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
// Mutate neessary internal state — effective_address_[0] is exposed
// on the data bus as the accepted interrupt number during the interrupt
// acknowledge cycle, with the low bit set since a real 68000 uses the lower
// data strobe to collect the corresponding vector byte.
// acknowledge cycle, with all other bits set, including the low bit as
// a real 68000 uses the lower data strobe to collect the corresponding vector byte.
//
// Cf. M68000 8-/16-/32-BIT MICROPROCESSORS USER'S MANUAL 5.1.4.
accepted_interrupt_level_ = interrupt_level_ = bus_interrupt_level_;
effective_address_[0].full = 1 | uint32_t(accepted_interrupt_level_ << 1);
effective_address_[0].full = 0xfffffff1 | uint32_t(accepted_interrupt_level_ << 1);
// Recede the program counter to where it would have been were there no
// prefetch; that's where the reading stream should pick up upon RTE.