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Implements TCD, TDC, TCS, TSC.

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This commit is contained in:
Thomas Harte 2020-10-10 21:43:05 -04:00
parent aface1f8be
commit b8848d8580
2 changed files with 27 additions and 8 deletions
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33
Processors/65816/Implementation/65816Implementation.hpp
View File

@ -26,6 +26,7 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
#define x() (x_.full & x_masks_[1])
#define y() (y_.full & x_masks_[1])
#define stack_address() ((s_.full & e_masks_[1]) | (0x0100 & e_masks_[0]))
Cycles number_of_cycles = cycles + cycles_left_to_run_;
while(number_of_cycles > Cycles(0)) {
@ -143,11 +144,7 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
//
#define stack_access(value, operation) \
if(emulation_flag_) { \
bus_address = s_.halves.low | 0x100; \
} else { \
bus_address = s_.full; \
} \
bus_address = stack_address(); \
bus_value = value; \
bus_operation = operation;
@ -369,7 +366,7 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
switch(active_instruction_->operation) {
//
// Loads, stores and transfers (and NOP).
// Loads, stores and transfers (and NOP, and XBA).
//
case LDA:
@ -450,7 +447,7 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
// The below attempt to obey the 8/16-bit mixed transfer rules
// as documented in https://softpixel.com/~cwright/sianse/docs/65816NFO.HTM
// (and makes reasonable guesses as to the N flag)
// (and make reasonable guesses as to the N flag).
case TXS:
s_ = x_.full & x_masks_[1];
@ -491,6 +488,26 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
flags_.set_nz(a_.full, m_shift_);
break;
case TCD:
direct_ = a_.full;
flags_.set_nz(a_.full, 8);
break;
case TDC:
a_.full = direct_;
flags_.set_nz(a_.full, 8);
break;
case TCS:
s_.full = a_.full;
// No need to worry about byte masking here; for the stack it's handled as the emulation runs.
break;
case TSC:
a_.full = stack_address();
flags_.set_nz(a_.full, 8);
break;
case XBA: {
const uint8_t a_low = a_.halves.low;
a_.halves.low = a_.halves.high;
@ -793,7 +810,6 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
// TRB, TSB,
// STP, WAI,
// RTL,
// TCD, TCS, TDC, TSC
default:
assert(false);
@ -820,6 +836,7 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
#undef y
#undef m_flag
#undef x_flag
#undef stack_address
cycles_left_to_run_ = number_of_cycles;
}

2
Processors/65816/Implementation/65816Storage.cpp
View File

@ -1046,6 +1046,8 @@ void ProcessorStorage::set_emulation_mode(bool enabled) {
} else {
e_masks_[0] = 0x0000;
e_masks_[1] = 0xffff;
s_.halves.high = 1; // To pretend it was 1 all along; this implementation actually ignores
// the top byte while in emulation mode.
}
emulation_flag_ = enabled;