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Make the flag adjustment a little more consistent with the rest of my emulators.

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Signed-off-by: Adrian.Conlon <adrian.conlon@gmail.com>
This commit is contained in:
Adrian.Conlon
2017-07-16 10:05:49 +01:00
parent d1bb49143d
commit d522b694bd
2 changed files with 29 additions and 29 deletions
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10
M6502/inc/mos6502.h
View File

@@ -58,12 +58,12 @@ namespace EightBit {
virtual int Execute(uint8_t cell); virtual int Execute(uint8_t cell);
private: private:
void UpdateZeroFlag(uint8_t datum) { clearFlag(P(), ZF, datum); } void adjustZero(uint8_t datum) { clearFlag(P(), ZF, datum); }
void UpdateNegativeFlag(uint8_t datum) { setFlag(P(), NF, datum & NF); } void adjustNegative(uint8_t datum) { setFlag(P(), NF, datum & NF); }
void UpdateZeroNegativeFlags(uint8_t datum) { void adjustNZ(uint8_t datum) {
UpdateZeroFlag(datum); adjustZero(datum);
UpdateNegativeFlag(datum); adjustNegative(datum);
} }
void PushByte(uint8_t value); void PushByte(uint8_t value);

48
M6502/src/mos6502.cpp
View File

@@ -160,7 +160,7 @@ int EightBit::MOS6502::Execute(uint8_t cell) {
RTS(); RTS();
break; break;
case 0b010: // PLA case 0b010: // PLA
UpdateZeroNegativeFlags(A() = PopByte()); adjustNZ(A() = PopByte());
break; break;
case 0b011: // JMP (abs) case 0b011: // JMP (abs)
JMP_ind(); JMP_ind();
@@ -184,7 +184,7 @@ int EightBit::MOS6502::Execute(uint8_t cell) {
Branch(!(P() & CF)); Branch(!(P() & CF));
break; break;
case 0b110: // TYA case 0b110: // TYA
UpdateZeroNegativeFlags(A() = Y()); adjustNZ(A() = Y());
break; break;
default: // STY default: // STY
AM_00(bbb, false) = Y(); AM_00(bbb, false) = Y();
@@ -194,7 +194,7 @@ int EightBit::MOS6502::Execute(uint8_t cell) {
case 0b101: case 0b101:
switch (bbb) { switch (bbb) {
case 0b010: // TAY case 0b010: // TAY
UpdateZeroNegativeFlags(Y() = A()); adjustNZ(Y() = A());
break; break;
case 0b100: // BCS case 0b100: // BCS
Branch((P() & CF) != 0); Branch((P() & CF) != 0);
@@ -288,7 +288,7 @@ int EightBit::MOS6502::Execute(uint8_t cell) {
case 0b100: case 0b100:
switch (bbb) { switch (bbb) {
case 0b010: // TXA case 0b010: // TXA
UpdateZeroNegativeFlags(A() = X()); adjustNZ(A() = X());
break; break;
case 0b110: // TXS case 0b110: // TXS
S() = X(); S() = X();
@@ -301,7 +301,7 @@ int EightBit::MOS6502::Execute(uint8_t cell) {
case 0b101: case 0b101:
switch (bbb) { switch (bbb) {
case 0b110: // TSX case 0b110: // TSX
UpdateZeroNegativeFlags(X() = S()); adjustNZ(X() = S());
break; break;
default: // LDX default: // LDX
LDX(AM_10_x(bbb)); LDX(AM_10_x(bbb));
@@ -374,48 +374,48 @@ void EightBit::MOS6502::FetchWord(register16_t& output) {
//// ////
void EightBit::MOS6502::DEC(uint8_t& target) { void EightBit::MOS6502::DEC(uint8_t& target) {
UpdateZeroNegativeFlags(--target); adjustNZ(--target);
} }
void EightBit::MOS6502::ROR(uint8_t& output) { void EightBit::MOS6502::ROR(uint8_t& output) {
auto carry = P() & CF; auto carry = P() & CF;
setFlag(P(), CF, output & CF); setFlag(P(), CF, output & CF);
output = (output >> 1) | (carry << 7); output = (output >> 1) | (carry << 7);
UpdateZeroNegativeFlags(output); adjustNZ(output);
} }
void EightBit::MOS6502::LSR(uint8_t& output) { void EightBit::MOS6502::LSR(uint8_t& output) {
setFlag(P(), CF, output & CF); setFlag(P(), CF, output & CF);
UpdateZeroNegativeFlags(output >>= 1); adjustNZ(output >>= 1);
} }
void EightBit::MOS6502::BIT(uint8_t data) { void EightBit::MOS6502::BIT(uint8_t data) {
UpdateZeroFlag(A() & data); adjustZero(A() & data);
UpdateNegativeFlag(data); adjustNegative(data);
setFlag(P(), VF, data & VF); setFlag(P(), VF, data & VF);
} }
void EightBit::MOS6502::INC(uint8_t& output) { void EightBit::MOS6502::INC(uint8_t& output) {
UpdateZeroNegativeFlags(++output); adjustNZ(++output);
} }
void EightBit::MOS6502::ROL(uint8_t& output) { void EightBit::MOS6502::ROL(uint8_t& output) {
uint8_t result = (output << 1) | (P() & CF); uint8_t result = (output << 1) | (P() & CF);
setFlag(P(), CF, output & Bit7); setFlag(P(), CF, output & Bit7);
UpdateZeroNegativeFlags(output = result); adjustNZ(output = result);
} }
void EightBit::MOS6502::ASL(uint8_t& output) { void EightBit::MOS6502::ASL(uint8_t& output) {
setFlag(P(), CF, (output & 0x80) >> 7); setFlag(P(), CF, (output & 0x80) >> 7);
UpdateZeroNegativeFlags(output <<= 1); adjustNZ(output <<= 1);
} }
void EightBit::MOS6502::ORA(uint8_t data) { void EightBit::MOS6502::ORA(uint8_t data) {
UpdateZeroNegativeFlags(A() |= data); adjustNZ(A() |= data);
} }
void EightBit::MOS6502::AND(uint8_t data) { void EightBit::MOS6502::AND(uint8_t data) {
UpdateZeroNegativeFlags(A() &= data); adjustNZ(A() &= data);
} }
void EightBit::MOS6502::SBC(uint8_t data) { void EightBit::MOS6502::SBC(uint8_t data) {
@@ -429,7 +429,7 @@ void EightBit::MOS6502::SBC_b(uint8_t data) {
register16_t difference; register16_t difference;
difference.word = A() - data - (~P() & CF); difference.word = A() - data - (~P() & CF);
UpdateZeroNegativeFlags(difference.low); adjustNZ(difference.low);
setFlag(P(), VF, (A() ^ data) & (A() ^ difference.low) & 0x80); setFlag(P(), VF, (A() ^ data) & (A() ^ difference.low) & 0x80);
clearFlag(P(), CF, difference.high); clearFlag(P(), CF, difference.high);
@@ -442,7 +442,7 @@ void EightBit::MOS6502::SBC_d(uint8_t data) {
register16_t difference; register16_t difference;
difference.word = A() - data - carry; difference.word = A() - data - carry;
UpdateZeroNegativeFlags(difference.low); adjustNZ(difference.low);
setFlag(P(), VF, (A() ^ data) & (A() ^ difference.low) & 0x80); setFlag(P(), VF, (A() ^ data) & (A() ^ difference.low) & 0x80);
clearFlag(P(), CF, difference.high); clearFlag(P(), CF, difference.high);
@@ -462,26 +462,26 @@ void EightBit::MOS6502::SBC_d(uint8_t data) {
} }
void EightBit::MOS6502::EOR(uint8_t data) { void EightBit::MOS6502::EOR(uint8_t data) {
UpdateZeroNegativeFlags(A() ^= data); adjustNZ(A() ^= data);
} }
void EightBit::MOS6502::CMP(uint8_t first, uint8_t second) { void EightBit::MOS6502::CMP(uint8_t first, uint8_t second) {
register16_t result; register16_t result;
result.word = first - second; result.word = first - second;
UpdateZeroNegativeFlags(result.low); adjustNZ(result.low);
clearFlag(P(), CF, result.high); clearFlag(P(), CF, result.high);
} }
void EightBit::MOS6502::LDA(uint8_t data) { void EightBit::MOS6502::LDA(uint8_t data) {
UpdateZeroNegativeFlags(A() = data); adjustNZ(A() = data);
} }
void EightBit::MOS6502::LDY(uint8_t data) { void EightBit::MOS6502::LDY(uint8_t data) {
UpdateZeroNegativeFlags(Y() = data); adjustNZ(Y() = data);
} }
void EightBit::MOS6502::LDX(uint8_t data) { void EightBit::MOS6502::LDX(uint8_t data) {
UpdateZeroNegativeFlags(X() = data); adjustNZ(X() = data);
} }
void EightBit::MOS6502::ADC(uint8_t data) { void EightBit::MOS6502::ADC(uint8_t data) {
@@ -496,7 +496,7 @@ void EightBit::MOS6502::ADC_b(uint8_t data) {
register16_t sum; register16_t sum;
sum.word = A() + data + (P() & CF); sum.word = A() + data + (P() & CF);
UpdateZeroNegativeFlags(sum.low); adjustNZ(sum.low);
setFlag(P(), VF, ~(A() ^ data) & (A() ^ sum.low) & 0x80); setFlag(P(), VF, ~(A() ^ data) & (A() ^ sum.low) & 0x80);
setFlag(P(), CF, sum.high & CF); setFlag(P(), CF, sum.high & CF);
@@ -509,7 +509,7 @@ void EightBit::MOS6502::ADC_d(uint8_t data) {
register16_t sum; register16_t sum;
sum.word = A() + data + carry; sum.word = A() + data + carry;
UpdateZeroNegativeFlags(sum.low); adjustNZ(sum.low);
auto low = (uint8_t)(lowNibble(A()) + lowNibble(data) + carry); auto low = (uint8_t)(lowNibble(A()) + lowNibble(data) + carry);
if (low > 9) if (low > 9)