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Reflect that the I/O for Intel style processors isn't part of the CPU, but attached to the Bus and access controlled by the CPU.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon
2020-02-09 11:51:58 +00:00
parent dc37d61797
commit c8bdabf34f
24 changed files with 410 additions and 279 deletions
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M6502/src/mos6502.cpp
+28 -28
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@@ -249,30 +249,30 @@ int EightBit::MOS6502::execute() {
case 0x7f: rra(AM_AbsoluteX()); break; // *RRA (absolute, X)
case 0x80: AM_Immediate(); break; // *NOP (immediate)
case 0x81: Processor::busWrite(Address_IndexedIndirectX(), A()); break; // STA (indexed indirect X)
case 0x81: memoryWrite(Address_IndexedIndirectX(), A()); break; // STA (indexed indirect X)
case 0x82: AM_Immediate(); break; // *NOP (immediate)
case 0x83: Processor::busWrite(Address_IndexedIndirectX(), A() & X()); break; // *SAX (indexed indirect X)
case 0x84: Processor::busWrite(Address_ZeroPage(), Y()); break; // STY (zero page)
case 0x85: Processor::busWrite(Address_ZeroPage(), A()); break; // STA (zero page)
case 0x86: Processor::busWrite(Address_ZeroPage(), X()); break; // STX (zero page)
case 0x87: Processor::busWrite(Address_ZeroPage(), A() & X()); break; // *SAX (zero page)
case 0x83: memoryWrite(Address_IndexedIndirectX(), A() & X()); break; // *SAX (indexed indirect X)
case 0x84: memoryWrite(Address_ZeroPage(), Y()); break; // STY (zero page)
case 0x85: memoryWrite(Address_ZeroPage(), A()); break; // STA (zero page)
case 0x86: memoryWrite(Address_ZeroPage(), X()); break; // STX (zero page)
case 0x87: memoryWrite(Address_ZeroPage(), A() & X()); break; // *SAX (zero page)
case 0x88: busRead(); Y() = dec(Y()); break; // DEY (implied)
case 0x89: AM_Immediate(); break; // *NOP (immediate)
case 0x8a: busRead(); A() = through(X()); break; // TXA (implied)
case 0x8b: break;
case 0x8c: Processor::busWrite(Address_Absolute(), Y()); break; // STY (absolute)
case 0x8d: Processor::busWrite(Address_Absolute(), A()); break; // STA (absolute)
case 0x8e: Processor::busWrite(Address_Absolute(), X()); break; // STX (absolute)
case 0x8f: Processor::busWrite(Address_Absolute(), A() & X()); break; // *SAX (absolute)
case 0x8c: memoryWrite(Address_Absolute(), Y()); break; // STY (absolute)
case 0x8d: memoryWrite(Address_Absolute(), A()); break; // STA (absolute)
case 0x8e: memoryWrite(Address_Absolute(), X()); break; // STX (absolute)
case 0x8f: memoryWrite(Address_Absolute(), A() & X()); break; // *SAX (absolute)
case 0x90: branch(!carry()); break; // BCC (relative)
case 0x91: AM_IndirectIndexedY(); Processor::busWrite(A()); break; // STA (indirect indexed Y)
case 0x91: AM_IndirectIndexedY(); memoryWrite(A()); break; // STA (indirect indexed Y)
case 0x92: break;
case 0x93: break;
case 0x94: Processor::busWrite(Address_ZeroPageX(), Y()); break; // STY (zero page, X)
case 0x95: Processor::busWrite(Address_ZeroPageX(), A()); break; // STA (zero page, X)
case 0x96: Processor::busWrite(Address_ZeroPageY(), X()); break; // STX (zero page, Y)
case 0x97: Processor::busWrite(Address_ZeroPageY(), A() & X()); break; // *SAX (zero page, Y)
case 0x94: memoryWrite(Address_ZeroPageX(), Y()); break; // STY (zero page, X)
case 0x95: memoryWrite(Address_ZeroPageX(), A()); break; // STA (zero page, X)
case 0x96: memoryWrite(Address_ZeroPageY(), X()); break; // STX (zero page, Y)
case 0x97: memoryWrite(Address_ZeroPageY(), A() & X()); break; // *SAX (zero page, Y)
case 0x98: busRead(); A() = through(Y()); break; // TYA (implied)
case 0x99: sta_AbsoluteY(); break; // STA (absolute, Y)
case 0x9a: busRead(); S() = X(); break; // TXS (implied)
@@ -426,13 +426,13 @@ EightBit::register16_t EightBit::MOS6502::Address_Indirect() {
uint8_t EightBit::MOS6502::Address_ZeroPageX() {
const auto address = Address_ZeroPage();
Processor::busRead(address);
memoryRead(address);
return address + X();
}
uint8_t EightBit::MOS6502::Address_ZeroPageY() {
const auto address = Address_ZeroPage();
Processor::busRead(address);
memoryRead(address);
return address + Y();
}
@@ -472,18 +472,18 @@ uint8_t EightBit::MOS6502::AM_Immediate() {
}
uint8_t EightBit::MOS6502::AM_Absolute() {
return Processor::busRead(Address_Absolute());
return memoryRead(Address_Absolute());
}
uint8_t EightBit::MOS6502::AM_ZeroPage() {
return Processor::busRead(Address_ZeroPage());
return memoryRead(Address_ZeroPage());
}
uint8_t EightBit::MOS6502::AM_AbsoluteX(const PageCrossingBehavior behaviour) {
const auto [address, page] = Address_AbsoluteX();
auto possible = getBytePaged(page, address.low);
if ((behaviour == PageCrossingBehavior::AlwaysReadTwice) || UNLIKELY(page != address.high))
possible = Processor::busRead(address);
possible = memoryRead(address);
return possible;
}
@@ -491,27 +491,27 @@ uint8_t EightBit::MOS6502::AM_AbsoluteY() {
const auto[address, page] = Address_AbsoluteY();
auto possible = getBytePaged(page, address.low);
if (UNLIKELY(page != address.high))
possible = Processor::busRead(address);
possible = memoryRead(address);
return possible;
}
uint8_t EightBit::MOS6502::AM_ZeroPageX() {
return Processor::busRead(Address_ZeroPageX());
return memoryRead(Address_ZeroPageX());
}
uint8_t EightBit::MOS6502::AM_ZeroPageY() {
return Processor::busRead(Address_ZeroPageY());
return memoryRead(Address_ZeroPageY());
}
uint8_t EightBit::MOS6502::AM_IndexedIndirectX() {
return Processor::busRead(Address_IndexedIndirectX());
return memoryRead(Address_IndexedIndirectX());
}
uint8_t EightBit::MOS6502::AM_IndirectIndexedY() {
const auto [address, page] = Address_IndirectIndexedY();
auto possible = getBytePaged(page, address.low);
if (page != address.high)
possible = Processor::busRead(address);
possible = memoryRead(address);
return possible;
}
@@ -524,7 +524,7 @@ void EightBit::MOS6502::branch(const int condition) {
const auto page = PC().high;
jump(destination);
if (UNLIKELY(PC().high != page))
Processor::busRead(register16_t(PC().low, page));
memoryRead(register16_t(PC().low, page));
}
}
@@ -748,11 +748,11 @@ void EightBit::MOS6502::sre(const uint8_t value) {
void EightBit::MOS6502::sta_AbsoluteX() {
const auto [address, page] = Address_AbsoluteX();
getBytePaged(page, address.low);
Processor::busWrite(address, A());
memoryWrite(address, A());
}
void EightBit::MOS6502::sta_AbsoluteY() {
const auto [address, page] = Address_AbsoluteY();
getBytePaged(page, address.low);
Processor::busWrite(address, A());
memoryWrite(address, A());
}