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EightBit
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compare: 6502:93088b355c4dc54160a308e8c35318e91fef6c5c
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3 Commits
42afeb342f ... 93088b355c

Author SHA1 Message Date
Adrian Conlon 93088b355c M6502: Unify accumulator write page boundary fixup code 2023-12-31 14:58:15 +00:00
Adrian Conlon e4fbeebfa7 Correct problem in page boundary condition for M6502. 2023-12-31 14:32:16 +00:00
Adrian Conlon 84a2d0f952 Whoops: failed to check cycle problems in M6502 tests 2023-12-31 14:21:17 +00:00
3 changed files with 19 additions and 8 deletions
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2
M6502/HarteTest_6502/checker_t.cpp
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@ -159,6 +159,8 @@ bool checker_t::checkState(test_t test) {
const auto& actual_action = std::get<2>(actual);
check("Cycle action", expected_action, std::string_view(actual_action));
}
if (!m_messages.empty())
return false;
const auto final = test.final();
const auto pc_good = check("PC", final.pc(), cpu.PC().word);

6
M6502/inc/mos6502.h
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@ -188,6 +188,12 @@ namespace EightBit {
void sta_AbsoluteX() noexcept;
void sta_AbsoluteY() noexcept;
void sta_IndirectIndexedY() noexcept;
void write_A_with_fixup(const register16_t& address, uint8_t unfixed_page) noexcept {
getBytePaged(unfixed_page, address.low); // Possible fixup for page boundary crossing
memoryWrite(address, A());
}
uint8_t x = 0; // index register X
uint8_t y = 0; // index register Y

19
M6502/src/mos6502.cpp
View File

@ -73,14 +73,14 @@ void EightBit::MOS6502::handleINT() noexcept {
void EightBit::MOS6502::interrupt() noexcept {
const bool reset = m_handlingRESET;
const bool nmi = m_handlingNMI;
const bool irq = m_handlingINT;
const bool hardware = nmi || irq || reset;
const bool software = !hardware;
if (reset) {
dummyPush(PC().high);
dummyPush(PC().low);
dummyPush(P());
} else {
const bool irq = m_handlingINT;
const bool hardware = nmi || irq || reset;
const bool software = !hardware;
pushWord(PC());
push(P() | (software ? BF : 0));
}
@ -266,7 +266,7 @@ int EightBit::MOS6502::execute() noexcept {
case 0x8f: memoryWrite(Address_Absolute(), A() & X()); break; // *SAX (absolute)
case 0x90: branch(!carry()); break; // BCC (relative)
case 0x91: memoryRead(Address_IndirectIndexedY().first); memoryWrite(A()); break; // STA (indirect indexed Y)
case 0x91: sta_IndirectIndexedY(); break; // STA (indirect indexed Y)
case 0x92: break;
case 0x93: break;
case 0x94: memoryWrite(Address_ZeroPageX(), Y()); break; // STY (zero page, X)
@ -748,12 +748,15 @@ void EightBit::MOS6502::sre(const uint8_t value) noexcept {
void EightBit::MOS6502::sta_AbsoluteX() noexcept {
const auto [address, page] = Address_AbsoluteX();
getBytePaged(page, address.low);
memoryWrite(address, A());
write_A_with_fixup(address, page);
}
void EightBit::MOS6502::sta_AbsoluteY() noexcept {
const auto [address, page] = Address_AbsoluteY();
getBytePaged(page, address.low);
memoryWrite(address, A());
write_A_with_fixup(address, page);
}
void EightBit::MOS6502::sta_IndirectIndexedY() noexcept {
const auto [address, page] = Address_IndirectIndexedY();
write_A_with_fixup(address, page);
}