6502/EightBit
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Fixes 8080 implmentation so tests run. Cycle counts wrong though

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This commit is contained in:
Adrian Conlon committed 2026-06-01 22:51:39 +01:00
1 parent 683fc0e878
commit c8c7cc461a
2 files changed
+37 -15
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Intel8080/inc/Intel8080.h
+1 -1
View File
@@ -125,7 +125,7 @@ namespace EightBit {
}
[[nodiscard]] static constexpr auto adjustAuxiliaryCarrySub(uint8_t f, uint8_t before, uint8_t value, int calculation) noexcept {
return setBit(f, AC, calculateHalfCarrySub(before, value, calculation));
return clearBit(f, AC, calculateHalfCarrySub(before, value, calculation));
}
void adjustAuxiliaryCarrySub(uint8_t before, uint8_t value, int calculation) noexcept {
Intel8080/src/Intel8080.cpp
+36 -14
View File
@@ -60,6 +60,7 @@ void EightBit::Intel8080::memoryUpdate(int ticks) noexcept {
void EightBit::Intel8080::handleRESET() noexcept {
IntelProcessor::handleRESET();
disableInterrupts();
SP() = AF() = Mask16;
}
void EightBit::Intel8080::handleINT() noexcept {
@@ -302,7 +303,7 @@ void EightBit::Intel8080::xhtl(register16_t& exchange) {
BUS().DATA() = exchange.low;
exchange.low = MEMPTR().low;
memoryUpdate();
tick(2);
tick(15); // 2(memUpdate) + 1(memUpdate) + 15 = 18 total
}
void EightBit::Intel8080::writePort(const uint8_t port) noexcept {
@@ -454,21 +455,23 @@ void EightBit::Intel8080::execute(const int x, const int y, const int z, const i
case 4: { // 8-bit INC
auto operand = R(y);
IntelProcessor::R(y, increment(operand));
tick(4);
tick(5);
if (UNLIKELY(y == 6)) // INC M: memRead(0) + memUpdate(1) + 5 + 4 = 10
tick(4);
break;
} case 5: { // 8-bit DEC
auto operand = R(y);
IntelProcessor::R(y, decrement(operand));
tick(4);
if (UNLIKELY(y == 6))
tick(7);
tick(5);
if (UNLIKELY(y == 6)) // DEC M: memRead(0) + memUpdate(1) + 5 + 4 = 10
tick(4);
break;
} case 6: // 8-bit load immediate
fetchByte();
IntelProcessor::R(y, BUS().DATA());
tick(7);
if (UNLIKELY(y == 6))
tick(3);
if (UNLIKELY(y == 6)) // LD M,n: memUpdate(1) + 7 + 2 = 10
tick(2);
break;
case 7: // Assorted operations on accumulator/flags
switch (y) {
@@ -508,12 +511,15 @@ void EightBit::Intel8080::execute(const int x, const int y, const int z, const i
case 1: // 8-bit loading
if (UNLIKELY(z == 6 && y == 6)) { // Exception (replaces LD (HL), (HL))
lowerHALT();
tick(4);
} else {
IntelProcessor::R(y, R(z));
if (UNLIKELY((y == 6) || (z == 6))) // M operations
tick(3);
tick(5);
if (UNLIKELY(y == 6)) // MOV M,r: memUpdate(1) + 5 + 1 = 7
tick(1);
else if (UNLIKELY(z == 6)) // MOV r,M: memRead(0) + 5 + 2 = 7
tick(2);
}
tick(4);
break;
case 2: { // Operate on accumulator and register/memory location
const auto value = R(z);
@@ -576,10 +582,11 @@ void EightBit::Intel8080::execute(const int x, const int y, const int z, const i
break;
case 2: // JP HL
Processor::jump(HL());
tick(5);
break;
case 3: // LD SP,HL
SP() = HL();
tick(4);
tick(5);
break;
}
break;
@@ -589,40 +596,54 @@ void EightBit::Intel8080::execute(const int x, const int y, const int z, const i
break;
case 2: // Conditional jump
jumpConditionalFlag(y);
tick(10);
break;
case 3: // Assorted operations
switch (y) {
case 0: // JP nn
fetchInto(MEMPTR());
jump();
tick(10);
break;
case 2: // OUT (n),A
fetchByte();
writePort(BUS().DATA());
tick(10);
break;
case 3: // IN A,(n)
fetchByte();
readPort(BUS().DATA());
A() = BUS().DATA();
tick(11);
tick(10);
break;
case 4: // EX (SP),HL
xhtl(HL());
break;
case 5: // EX DE,HL
std::swap(DE(), HL());
tick(5);
break;
case 6: // DI
disableInterrupts();
tick(4);
break;
case 7: // EI
enableInterrupts();
tick(4);
break;
}
break;
case 4: // Conditional call: CALL cc[y], nn
callConditionalFlag(y);
case 4: { // Conditional call: CALL cc[y], nn
const bool condition = convertCondition(y);
fetchInto(MEMPTR());
if (condition) {
call();
tick(17);
} else {
tick(11);
}
break;
}
case 5: // PUSH & various ops
switch (q) {
case 0: // PUSH rp2[p]
@@ -672,6 +693,7 @@ void EightBit::Intel8080::execute(const int x, const int y, const int z, const i
default:
UNREACHABLE;
}
tick(7);
break;
}
case 7: // Restart: RST y * 8