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Thomas Harte 2023-09-02 14:45:13 -04:00
parent ecec9ff6dc
commit 43dfb729d3
1 changed files with 3 additions and 2 deletions
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Processors/6502/Implementation/6502Implementation.hpp
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@ -305,8 +305,9 @@ template <Personality personality, typename T, bool uses_ready_line> void Proces
// So just test for carry (well, actually borrow, which is !carry).
// The bottom nibble is adjusted if there was borrow into the top nibble;
// on a 6502 this doesn't cause additional carry but on a 65C02 it does.
// This difference affects invalid BCD numbers only.
// on a 6502 additional borrow isn't propagated but on a 65C02 it is.
// This difference affects invalid BCD numbers only — valid numbers will
// never be less than -9 so adding 10 will always generate carry.
if(!Numeric::carried_in<4>(a_, operand_, result)) {
if constexpr (is_65c02(personality)) {
result += 0xfa;