6502/EightBit
1
0
Fork 0
mirror of https://github.com/MoleskiCoder/EightBit.git synced 2025-01-30 03:32:13 +00:00
Code Issues Projects Releases Wiki Activity

M6502: Unify accumulator write page boundary fixup code

Browse Source
This commit is contained in:
Adrian Conlon 2023-12-31 14:58:15 +00:00
parent e4fbeebfa7
commit 93088b355c
2 changed files with 11 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
M6502/inc/mos6502.h
View File

@ -190,6 +190,11 @@ namespace EightBit {
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
uint8_t a = 0; // accumulator

15
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));
}
@ -748,18 +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();
getBytePaged(page, address.low); // Possible fixup for page boundary crossing
memoryWrite(address, A());
write_A_with_fixup(address, page);
}