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Add to-memory write-back. Am going to reconsider usage of temporary_address_ as noted.

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This commit is contained in:
Thomas Harte 2022-05-19 11:23:26 -04:00
parent f46e7c65c5
commit 274902c3c1
1 changed files with 23 additions and 5 deletions
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28
Processors/68000Mk2/Implementation/68000Mk2Implementation.hpp
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@ -29,6 +29,7 @@ enum ExecutionState: int {
FetchOperand_l, FetchOperand_l,
StoreOperand, StoreOperand,
StoreOperand_l,
// Specific addressing mode fetches. // Specific addressing mode fetches.
@ -167,8 +168,8 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
// Sets up the next data access — its address and size/read flags. // Sets up the next data access — its address and size/read flags.
#define SetupDataAccess(addr, read_flag, select_flag) \ #define SetupDataAccess(addr, read_flag, select_flag) \
access.address = access_announce.address = &addr; \ access.address = access_announce.address = &addr; \
access_announce.operation = Microcycle::NewAddress | Microcycle::IsData | read_flag; \ access_announce.operation = Microcycle::NewAddress | Microcycle::IsData | (read_flag); \
access.operation = access_announce.operation | select_flag; access.operation = access_announce.operation | (select_flag);
// Performs the access established by SetupDataAccess into val. // Performs the access established by SetupDataAccess into val.
#define Access(val) \ #define Access(val) \
@ -407,6 +408,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
Access(operand_[next_operand_].low); // nr Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_bw); MoveToNextOperand(FetchOperand_bw);
// TODO: avoid use of temporary_address_ here and probably above.
BeginState(FetchAddressRegisterIndirect_l): BeginState(FetchAddressRegisterIndirect_l):
effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l; effective_address_[next_operand_] = registers_[8 + instruction_.reg(next_operand_)].l;
@ -414,6 +416,7 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
Access(operand_[next_operand_].high); // nR Access(operand_[next_operand_].high); // nR
temporary_address_ += 2; temporary_address_ += 2;
effective_address_[next_operand_] += 2;
Access(operand_[next_operand_].low); // nr Access(operand_[next_operand_].low); // nr
MoveToNextOperand(FetchOperand_l); MoveToNextOperand(FetchOperand_l);
@ -428,9 +431,24 @@ void Processor<BusHandler, dtack_is_implicit, permit_overrun, signal_will_perfor
MoveToState(Decode); MoveToState(Decode);
} }
// TODO: make a decision on how I'm going to deal with byte/word/longword. if(instruction_.operand_size() == InstructionSet::M68k::DataSize::LongWord) {
assert(false); MoveToState(StoreOperand_l);
break; }
SetupDataAccess(
effective_address_[next_operand_],
0,
(instruction_.operand_size() == InstructionSet::M68k::DataSize::Byte) ? Microcycle::SelectByte : Microcycle::SelectWord);
Access(operand_[next_operand_].low); // nw
MoveToState(Decode);
BeginState(StoreOperand_l):
SetupDataAccess(effective_address_[next_operand_], 0, Microcycle::SelectWord);
Access(operand_[next_operand_].low); // nw
effective_address_[next_operand_] -= 2;
Access(operand_[next_operand_].high); // nW
MoveToState(Decode);
// //
// Various generic forms of perform. // Various generic forms of perform.