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cpu/decoder - Implement DAA

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This is a best effort implementation, possible quirks of the actual
hardware have not been considered.
This commit is contained in:
madmaurice 2023-08-30 12:55:16 +02:00
parent 2d4daf821e
commit 3d244d1ec0
1 changed files with 15 additions and 1 deletions
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16
cpu/decoder.cpp
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@ -427,7 +427,21 @@ void Cpu::executeInstruction()
state.halfcarry = false;
break;
// TODO: case 0x27: break; // DAA
case 0x27: // DAA
{
u16 corr = 0;
if (state.halfcarry || ((state.A & 0x0F) > 0x9))
corr |= 0x06;
if ((state.A & 0xF0) > 0x90)
corr |= 0x06;
u32 res16 = (u16)state.A + (state.subtract ? (-corr) : corr);
state.A = (u8)res16;
state.halfcarry = false;
state.zero = (state.A == 0);
state.carry = (res16 & 0x100);
}
break;
case 0x2F: // CPL Complement accumulator
state.A = ~state.A;