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Ensure IO cycles don't produce an address of (PC+1).

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This commit is contained in:
Thomas Harte 2022-06-21 11:41:05 -04:00
parent ab0c290489
commit ec98736bd7
3 changed files with 53 additions and 47 deletions
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4
Processors/65816/Implementation/65816Implementation.hpp
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@ -99,6 +99,10 @@ template <typename BusHandler, bool uses_ready_line> void Processor<BusHandler,
perform_bus(registers_.pc | registers_.program_bank, &bus_throwaway_, MOS6502Esque::InternalOperationRead); perform_bus(registers_.pc | registers_.program_bank, &bus_throwaway_, MOS6502Esque::InternalOperationRead);
break; break;
case CycleFetchPreviousPCThrowaway:
perform_bus(((registers_.pc - 1) & 0xffff) | registers_.program_bank, &bus_throwaway_, MOS6502Esque::InternalOperationRead);
break;
// //
// Data fetches and stores. // Data fetches and stores.
// //

94
Processors/65816/Implementation/65816Storage.cpp
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@ -387,7 +387,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 8. Accumulator; A. // 8. Accumulator; A.
static void accumulator(AccessType, bool, const std::function<void(MicroOp)> &target) { static void accumulator(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
// TODO: seriously consider a-specific versions of all relevant operations; // TODO: seriously consider a-specific versions of all relevant operations;
// the cost of interpreting three things here is kind of silly. // the cost of interpreting three things here is kind of silly.
@ -416,10 +416,10 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 10a. Direct; d. // 10a. Direct; d.
// (That's zero page in 6502 terms) // (That's zero page in 6502 terms)
static void direct(AccessType type, bool is8bit, const std::function<void(MicroOp)> &target) { static void direct(AccessType type, bool is8bit, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirect); target(OperationConstructDirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
read_write(type, is8bit, target); read_write(type, is8bit, target);
} }
@ -430,7 +430,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirect); target(OperationConstructDirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
read_modify_write(is8bit, target); read_modify_write(is8bit, target);
} }
@ -440,9 +440,9 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirectIndexedIndirect); target(OperationConstructDirectIndexedIndirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.
target(CycleFetchData); // AAH. target(CycleFetchData); // AAH.
@ -458,7 +458,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirect); target(OperationConstructDirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.
target(CycleFetchData); // AAH. target(CycleFetchData); // AAH.
@ -473,7 +473,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirect); target(OperationConstructDirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.
target(CycleFetchData); // AAH. target(CycleFetchData); // AAH.
@ -490,7 +490,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirect); target(OperationConstructDirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.
target(CycleFetchIncrementData); // AAH. target(CycleFetchIncrementData); // AAH.
@ -506,7 +506,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirectLong); target(OperationConstructDirectLong);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.
target(CycleFetchIncrementData); // AAH. target(CycleFetchIncrementData); // AAH.
@ -522,9 +522,9 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirectX); target(OperationConstructDirectX);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
read_write(type, is8bit, target); read_write(type, is8bit, target);
} }
@ -534,9 +534,9 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirectX); target(OperationConstructDirectX);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
read_modify_write(is8bit, target); read_modify_write(is8bit, target);
} }
@ -546,9 +546,9 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirectY); target(OperationConstructDirectY);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
read_write(type, is8bit, target); read_write(type, is8bit, target);
} }
@ -563,20 +563,20 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
static void immediate_rep_sep(AccessType, bool, const std::function<void(MicroOp)> &target) { static void immediate_rep_sep(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // IDL. target(CycleFetchIncrementPC); // IDL.
target(CycleFetchPCThrowaway); // "Add 1 cycle for REP and SEP" target(CycleFetchPreviousPCThrowaway); // "Add 1 cycle for REP and SEP"
target(OperationPerform); target(OperationPerform);
} }
// 19a. Implied; i. // 19a. Implied; i.
static void implied(AccessType, bool, const std::function<void(MicroOp)> &target) { static void implied(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationPerform); target(OperationPerform);
} }
// 19b. Implied; i; XBA. // 19b. Implied; i; XBA.
static void implied_xba(AccessType, bool, const std::function<void(MicroOp)> &target) { static void implied_xba(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationPerform); target(OperationPerform);
} }
@ -584,8 +584,8 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 19d. Wait for interrupt. // 19d. Wait for interrupt.
static void stp_wai(AccessType, bool, const std::function<void(MicroOp)> &target) { static void stp_wai(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(OperationPerform); // Establishes the termination condition. target(OperationPerform); // Establishes the termination condition.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleRepeatingNone); // This will first check whether the STP/WAI exit target(CycleRepeatingNone); // This will first check whether the STP/WAI exit
// condition has occurred; if not then it'll issue // condition has occurred; if not then it'll issue
// either a BusOperation::None or ::Ready and then // either a BusOperation::None or ::Ready and then
@ -594,34 +594,34 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 20. Relative; r. // 20. Relative; r.
static void relative(AccessType, bool, const std::function<void(MicroOp)> &target) { static void relative(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // Offset. target(CycleFetchIncrementPC); // Offset.
target(OperationPerform); // The branch instructions will all skip one or three target(OperationPerform); // The branch instructions will all skip one or three
// of the next cycles, depending on the effect of // of the next cycles, depending on the effect of
// the jump. It'll also calculate the correct target // the jump. It'll also calculate the correct target
// address, placing it into the data buffer. // address, placing it into the data buffer.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationCopyDataToPC); // Install the address that was calculated above. target(OperationCopyDataToPC); // Install the address that was calculated above.
} }
// 21. Relative long; rl. // 21. Relative long; rl.
static void relative_long(AccessType, bool, const std::function<void(MicroOp)> &target) { static void relative_long(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // Offset low. target(CycleFetchIncrementPC); // Offset low.
target(CycleFetchIncrementPC); // Offset high. target(CycleFetchIncrementPC); // Offset high.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationPerform); // [BRL] target(OperationPerform); // [BRL]
} }
// 22a. Stack; s, abort/irq/nmi/res. // 22a. Stack; s, abort/irq/nmi/res.
// //
// Combined here with reset, which is the same sequence but with a different stack access. // Combined here with reset, which is the same sequence but with a different stack access.
static void stack_exception_impl(AccessType, bool, const std::function<void(MicroOp)> &target, MicroOp stack_op) { static void stack_exception_impl(AccessType, bool, const std::function<void(MicroOp)> &target, MicroOp stack_op) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationPrepareException); // Populates the data buffer; if the exception is a target(OperationPrepareException); // Populates the data buffer; if the exception is a
// reset then switches to the reset tail program. // reset then switches to the reset tail program.
@ -654,8 +654,8 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 22b. Stack; s, PLx. // 22b. Stack; s, PLx.
static void stack_pull(AccessType, bool is8bit, const std::function<void(MicroOp)> &target) { static void stack_pull(AccessType, bool is8bit, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
if(!is8bit) target(CyclePull); // REG low. if(!is8bit) target(CyclePull); // REG low.
target(CyclePull); // REG [high]. target(CyclePull); // REG [high].
@ -665,7 +665,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 22c. Stack; s, PHx. // 22c. Stack; s, PHx.
static void stack_push(AccessType, bool is8bit, const std::function<void(MicroOp)> &target) { static void stack_push(AccessType, bool is8bit, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationPerform); target(OperationPerform);
@ -689,7 +689,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
target(CycleFetchIncrementPC); // DO. target(CycleFetchIncrementPC); // DO.
target(OperationConstructDirect); target(OperationConstructDirect);
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.
target(CycleFetchData); // AAH. target(CycleFetchData); // AAH.
@ -701,7 +701,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
static void stack_per(AccessType, bool, const std::function<void(MicroOp)> &target) { static void stack_per(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // Offset low. target(CycleFetchIncrementPC); // Offset low.
target(CycleFetchIncrementPC); // Offset high. target(CycleFetchIncrementPC); // Offset high.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationConstructPER); target(OperationConstructPER);
@ -711,8 +711,8 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 22g. Stack; s, RTI. // 22g. Stack; s, RTI.
static void stack_rti(AccessType, bool, const std::function<void(MicroOp)> &target) { static void stack_rti(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CyclePull); // P. target(CyclePull); // P.
target(CyclePull); // New PCL. target(CyclePull); // New PCL.
@ -724,8 +724,8 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 22h. Stack; s, RTS. // 22h. Stack; s, RTS.
static void stack_rts(AccessType, bool, const std::function<void(MicroOp)> &target) { static void stack_rts(AccessType, bool, const std::function<void(MicroOp)> &target) {
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(CyclePull); // PCL. target(CyclePull); // PCL.
target(CyclePull); // PCH. target(CyclePull); // PCH.
@ -772,7 +772,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 23. Stack Relative; d, s. // 23. Stack Relative; d, s.
static void stack_relative(AccessType type, bool is8bit, const std::function<void(MicroOp)> &target) { static void stack_relative(AccessType type, bool is8bit, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // SO. target(CycleFetchIncrementPC); // SO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationConstructStackRelative); target(OperationConstructStackRelative);
read_write(type, is8bit, target); read_write(type, is8bit, target);
@ -781,7 +781,7 @@ struct CPU::WDC65816::ProcessorStorageConstructor {
// 24. Stack Relative Indirect Indexed (d, s), y. // 24. Stack Relative Indirect Indexed (d, s), y.
static void stack_relative_indexed_indirect(AccessType type, bool is8bit, const std::function<void(MicroOp)> &target) { static void stack_relative_indexed_indirect(AccessType type, bool is8bit, const std::function<void(MicroOp)> &target) {
target(CycleFetchIncrementPC); // SO. target(CycleFetchIncrementPC); // SO.
target(CycleFetchPCThrowaway); // IO. target(CycleFetchPreviousPCThrowaway); // IO.
target(OperationConstructStackRelative); target(OperationConstructStackRelative);
target(CycleFetchIncrementData); // AAL. target(CycleFetchIncrementData); // AAL.

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

@ -13,6 +13,8 @@ enum MicroOp: uint8_t {
CycleFetchPC, CycleFetchPC,
/// Fetches a byte from the program counter without incrementing it, and throws it away. /// Fetches a byte from the program counter without incrementing it, and throws it away.
CycleFetchPCThrowaway, CycleFetchPCThrowaway,
/// Fetches a byte from (PC - 1), and throws it away; useful for IO cycles that immediately follow incremented PCs.
CycleFetchPreviousPCThrowaway,
/// The same as CycleFetchIncrementPC but indicates valid program address rather than valid data address. /// The same as CycleFetchIncrementPC but indicates valid program address rather than valid data address.
CycleFetchOpcode, CycleFetchOpcode,