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M6502: Couple of small C++ usage changes: shouldn't be any functional effects.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2018-01-12 23:32:06 +00:00
parent 177dbbcd33
commit 4bd1a1eab1
1 changed files with 13 additions and 20 deletions
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33
M6502/src/mos6502.cpp
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@ -440,20 +440,12 @@ int EightBit::MOS6502::execute(uint8_t cell) {
break;
case 0b111: // *SBC
switch (decoded.bbb) {
case 0b000: // *ISB
case 0b001:
case 0b011:
case 0b100:
case 0b101:
case 0b110:
case 0b111:
ISB(decoded.bbb);
break;
case 0b010:
A() = SBC(A(), AM_11(decoded.bbb));
break;
default:
UNREACHABLE;
default: // *ISB
ISB(decoded.bbb);
break;
}
break;
default:
@ -483,7 +475,7 @@ uint8_t EightBit::MOS6502::pop() {
////
void EightBit::MOS6502::ROR(uint8_t& output) {
auto carry = P() & CF;
const auto carry = P() & CF;
setFlag(P(), CF, output & CF);
output = (output >> 1) | (carry << 7);
adjustNZ(output);
@ -501,7 +493,7 @@ void EightBit::MOS6502::BIT(uint8_t data) {
}
void EightBit::MOS6502::ROL(uint8_t& output) {
uint8_t result = (output << 1) | (P() & CF);
const uint8_t result = (output << 1) | (P() & CF);
setFlag(P(), CF, output & Bit7);
adjustNZ(output = result);
}
@ -535,13 +527,14 @@ uint8_t EightBit::MOS6502::SUB_b(const uint8_t operand, const uint8_t data, cons
uint8_t EightBit::MOS6502::SUB_d(const uint8_t operand, const uint8_t data, const int borrow) {
MEMPTR().word = operand - data - borrow;
auto low = (uint8_t)(lowNibble(operand) - lowNibble(data) - borrow);
auto lowNegative = (int8_t)low < 0;
uint8_t low = lowNibble(operand) - lowNibble(data) - borrow;
const auto lowNegative = low & NF;
if (lowNegative)
low -= 6;
uint8_t high = highNibble(operand) - highNibble(data) - (lowNegative ? 1 : 0);
if ((int8_t)high < 0)
uint8_t high = highNibble(operand) - highNibble(data) - (lowNegative >> 7);
const auto highNegative = high & NF;
if (highNegative)
high -= 6;
return promoteNibble(high) | lowNibble(low);
@ -577,11 +570,11 @@ uint8_t EightBit::MOS6502::ADD_d(uint8_t operand, uint8_t data, int carry) {
MEMPTR().word = operand + data + carry;
auto low = (uint8_t)(lowNibble(operand) + lowNibble(data) + carry);
uint8_t low = lowNibble(operand) + lowNibble(data) + carry;
if (low > 9)
low += 6;
auto high = (uint8_t)(highNibble(operand) + highNibble(data) + (low > 0xf ? 1 : 0));
uint8_t high = highNibble(operand) + highNibble(data) + (low > 0xf ? 1 : 0);
setFlag(P(), VF, ~(operand ^ data) & (operand ^ promoteNibble(high)) & NF);
if (high > 9)
@ -589,7 +582,7 @@ uint8_t EightBit::MOS6502::ADD_d(uint8_t operand, uint8_t data, int carry) {
setFlag(P(), CF, high > 0xf);
return (uint8_t)(promoteNibble(high) | lowNibble(low));
return promoteNibble(high) | lowNibble(low);
}
////