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Fix IndexedIndirect/IndirectIndexed confusion, proceed to test 0x14.

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This commit is contained in:
Thomas Harte
2025-10-22 13:29:45 -04:00
parent 693b53baa2
commit 2f210ebe3b
3 changed files with 135 additions and 27 deletions
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45
Processors/6502Mk2/Decoder.hpp
View File

@@ -68,7 +68,6 @@ enum class AccessProgram {
ZeroXRead,
ZeroXModify,
ZeroXWrite,
ZeroXNOP,
ZeroYRead,
ZeroYModify,
@@ -112,14 +111,14 @@ struct Decoder<model, std::enable_if_t<is_6502(model)>> {
case 0xc0: return {Immediate, Operation::CPY};
case 0xe0: return {Immediate, Operation::CPX};
case 0x01: return {IndirectIndexedRead, Operation::ORA};
case 0x21: return {IndirectIndexedRead, Operation::AND};
case 0x41: return {IndirectIndexedRead, Operation::EOR};
case 0x61: return {IndirectIndexedRead, Operation::ADC};
case 0x81: return {IndirectIndexedWrite, Operation::STA};
case 0xa1: return {IndirectIndexedRead, Operation::LDA};
case 0xc1: return {IndirectIndexedRead, Operation::CMP};
case 0xe1: return {IndirectIndexedRead, Operation::SBC};
case 0x01: return {IndexedIndirectRead, Operation::ORA};
case 0x21: return {IndexedIndirectRead, Operation::AND};
case 0x41: return {IndexedIndirectRead, Operation::EOR};
case 0x61: return {IndexedIndirectRead, Operation::ADC};
case 0x81: return {IndexedIndirectWrite, Operation::STA};
case 0xa1: return {IndexedIndirectRead, Operation::LDA};
case 0xc1: return {IndexedIndirectRead, Operation::CMP};
case 0xe1: return {IndexedIndirectRead, Operation::SBC};
case 0x02: return {JAM, Operation::JAM};
case 0x22: return {JAM, Operation::JAM};
@@ -130,14 +129,14 @@ struct Decoder<model, std::enable_if_t<is_6502(model)>> {
case 0xc2: return {Implied, Operation::NOP};
case 0xe2: return {Implied, Operation::NOP};
case 0x03: return {IndirectIndexedModify, Operation::ASO};
case 0x23: return {IndirectIndexedModify, Operation::RLA};
case 0x43: return {IndirectIndexedModify, Operation::LSE};
case 0x63: return {IndirectIndexedModify, Operation::RRA};
case 0x83: return {IndirectIndexedWrite, Operation::SAX};
case 0xa3: return {IndirectIndexedRead, Operation::LAX};
case 0xc3: return {IndirectIndexedWrite, Operation::DCP};
case 0xe3: return {IndirectIndexedWrite, Operation::INS};
case 0x03: return {IndexedIndirectModify, Operation::ASO};
case 0x23: return {IndexedIndirectModify, Operation::RLA};
case 0x43: return {IndexedIndirectModify, Operation::LSE};
case 0x63: return {IndexedIndirectModify, Operation::RRA};
case 0x83: return {IndexedIndirectWrite, Operation::SAX};
case 0xa3: return {IndexedIndirectRead, Operation::LAX};
case 0xc3: return {IndexedIndirectWrite, Operation::DCP};
case 0xe3: return {IndexedIndirectWrite, Operation::INS};
case 0x04: return {ZeroRead, Operation::NOP};
case 0x24: return {ZeroRead, Operation::BIT};
@@ -283,14 +282,14 @@ struct Decoder<model, std::enable_if_t<is_6502(model)>> {
case 0xd3: return {IndirectIndexedModify, Operation::DCP};
case 0xf3: return {IndirectIndexedModify, Operation::INS};
case 0x14: return {ZeroXNOP, Operation::NOP};
case 0x34: return {ZeroXNOP, Operation::NOP};
case 0x54: return {ZeroXNOP, Operation::NOP};
case 0x74: return {ZeroXNOP, Operation::NOP};
case 0x14: return {ZeroXRead, Operation::NOP};
case 0x34: return {ZeroXRead, Operation::NOP};
case 0x54: return {ZeroXRead, Operation::NOP};
case 0x74: return {ZeroXRead, Operation::NOP};
case 0x94: return {ZeroXWrite, Operation::STY};
case 0xb4: return {ZeroXRead, Operation::LDY};
case 0xd4: return {ZeroXNOP, Operation::NOP};
case 0xf4: return {ZeroXNOP, Operation::NOP};
case 0xd4: return {ZeroXRead, Operation::NOP};
case 0xf4: return {ZeroXRead, Operation::NOP};
case 0x15: return {ZeroXRead, Operation::ORA};
case 0x35: return {ZeroXRead, Operation::AND};

99
Processors/6502Mk2/Implementation/6502.hpp
View File

@@ -78,6 +78,7 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
__builtin_unreachable();
// MARK: - Fetch/decode.
fetch_decode:
case ResumePoint::FetchDecode:
@@ -114,6 +115,28 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
CPU::MOS6502Mk2::perform<model>(Storage::decoded_.operation, registers, registers.a, Storage::opcode_);
goto fetch_decode;
// MARK: - Relative.
case access_program(Relative):
++registers.pc.full;
if(!test(Storage::decoded_.operation, registers)) {
goto fetch_decode;
}
Storage::address_ = registers.pc;
access(BusOperation::Read, Literal(registers.pc.full), throwaway);
registers.pc.full += int8_t(Storage::operand_);
if(registers.pc.halves.high == Storage::address_.halves.high) {
goto fetch_decode;
}
Storage::address_.halves.low = registers.pc.halves.low;
access(BusOperation::Read, Literal(Storage::address_.full), throwaway);
goto fetch_decode;
// MARK: - Zero.
case access_program(ZeroRead):
@@ -209,7 +232,7 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
// MARK: - Indexed indirect.
case access_program(IndirectIndexedRead):
case access_program(IndexedIndirectRead):
++registers.pc.full;
access(BusOperation::Read, ZeroPage(Storage::operand_), throwaway);
Storage::operand_ += registers.x;
@@ -221,7 +244,7 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
perform_operation();
goto fetch_decode;
case access_program(IndirectIndexedWrite):
case access_program(IndexedIndirectWrite):
++registers.pc.full;
access(BusOperation::Read, ZeroPage(Storage::operand_), throwaway);
Storage::operand_ += registers.x;
@@ -233,15 +256,83 @@ void Processor<model, Traits>::run_for(const Cycles cycles) {
access(BusOperation::Write, Literal(Storage::address_.full), Storage::operand_);
goto fetch_decode;
case access_program(IndexedIndirectModify):
++registers.pc.full;
access(BusOperation::Read, ZeroPage(Storage::operand_), throwaway);
Storage::operand_ += registers.x;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.low);
++Storage::operand_;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.high);
access(BusOperation::Read, Literal(Storage::address_.full), Storage::operand_);
access(BusOperation::Write, Literal(Storage::address_.full), Storage::operand_);
check_interrupt();
perform_operation();
access(BusOperation::Write, Literal(Storage::address_.full), Storage::operand_);
goto fetch_decode;
// MARK: - Indirect indexed.
case access_program(IndirectIndexedRead):
++registers.pc.full;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.low);
++Storage::operand_;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.high);
Storage::operand_ = Storage::address_.halves.high;
Storage::address_.full += registers.y;
if(Storage::address_.halves.high == Storage::operand_) {
goto skip_indirect_indexed_read_bonus_cycle;
}
std::swap(Storage::address_.halves.high, Storage::operand_);
access(BusOperation::Read, Literal(Storage::address_.full), throwaway);
std::swap(Storage::address_.halves.high, Storage::operand_);
skip_indirect_indexed_read_bonus_cycle:
check_interrupt();
access(BusOperation::Read, Literal(Storage::address_.full), Storage::operand_);
perform_operation();
goto fetch_decode;
case access_program(IndirectIndexedWrite):
++registers.pc.full;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.low);
++Storage::operand_;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.high);
Storage::operand_ = Storage::address_.halves.high;
Storage::address_.full += registers.y;
std::swap(Storage::address_.halves.high, Storage::operand_);
access(BusOperation::Read, Literal(Storage::address_.full), throwaway);
std::swap(Storage::address_.halves.high, Storage::operand_);
check_interrupt();
perform_operation();
access(BusOperation::Write, Literal(Storage::address_.full), Storage::operand_);
goto fetch_decode;
case access_program(IndirectIndexedModify):
++registers.pc.full;
access(BusOperation::Read, ZeroPage(Storage::operand_), throwaway);
Storage::operand_ += registers.x;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.low);
++Storage::operand_;
access(BusOperation::Read, ZeroPage(Storage::operand_), Storage::address_.halves.high);
Storage::operand_ = Storage::address_.halves.high;
Storage::address_.full += registers.y;
std::swap(Storage::address_.halves.high, Storage::operand_);
access(BusOperation::Read, Literal(Storage::address_.full), throwaway);
std::swap(Storage::address_.halves.high, Storage::operand_);
skip_indirect_indexed_modify_bonus_cycle:
access(BusOperation::Read, Literal(Storage::address_.full), Storage::operand_);
access(BusOperation::Write, Literal(Storage::address_.full), Storage::operand_);
check_interrupt();
perform_operation();
access(BusOperation::Write, Literal(Storage::address_.full), Storage::operand_);

18
Processors/6502Mk2/Perform.hpp
View File

@@ -14,6 +14,24 @@
namespace CPU::MOS6502Mk2 {
template <typename RegistersT>
bool test(const Operation operation, RegistersT &registers) {
switch(operation) {
default:
__builtin_unreachable();
case Operation::BPL: return !(registers.flags.negative_result & 0x80);
case Operation::BMI: return registers.flags.negative_result & 0x80;
case Operation::BVC: return !registers.flags.overflow;
case Operation::BVS: return registers.flags.overflow;
case Operation::BCC: return !registers.flags.carry;
case Operation::BCS: return registers.flags.carry;
case Operation::BNE: return registers.flags.zero_result;
case Operation::BEQ: return !registers.flags.zero_result;
case Operation::BRA: return true;
}
}
template <Model model, typename RegistersT>
void perform(const Operation operation, RegistersT &registers, uint8_t &operand, const uint8_t opcode) {
(void)opcode;