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6502X: Fix ADC with decimal mode enabled.

This commit is contained in:
SaxxonPike 2019-07-03 23:49:55 -05:00
parent 95db4f2159
commit cb48104d7a
1 changed files with 22 additions and 24 deletions
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46
BizHawk.Emulation.Cores/CPUs/MOS 6502X/Execute.cs
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@ -1659,34 +1659,32 @@ namespace BizHawk.Emulation.Cores.Components.M6502
}
void _Adc()
{
//TODO - an extra cycle penalty on 65C02 only
value8 = (byte)alu_temp;
if (FlagD && BCD_Enabled)
{
//TODO - an extra cycle penalty?
value8 = (byte)alu_temp;
if (FlagD && BCD_Enabled)
{
lo = (A & 0x0F) + (value8 & 0x0F) + (FlagC ? 1 : 0);
hi = (A & 0xF0) + (value8 & 0xF0);
if (lo > 0x09)
{
hi += 0x10;
lo += 0x06;
}
if (hi > 0x90) hi += 0x60;
FlagV = (~(A ^ value8) & (A ^ hi) & 0x80) != 0;
FlagC = hi > 0xFF;
A = (byte)((lo & 0x0F) | (hi & 0xF0));
}
else
{
tempint = value8 + A + (FlagC ? 1 : 0);
FlagV = (~(A ^ value8) & (A ^ tempint) & 0x80) != 0;
FlagC = tempint > 0xFF;
A = (byte)tempint;
}
tempint = (A & 0x0F) + (value8 & 0x0F) + (FlagC ? 0x01 : 0x00);
if (tempint > 0x09)
tempint += 0x06;
tempint = (tempint & 0x0F) + (A & 0xF0) + (value8 & 0xF0) + (tempint > 0x0F ? 0x10 : 0x00);
FlagV = (~(A ^ value8) & (A ^ tempint) & 0x80) != 0;
FlagZ = ((A + value8 + (FlagC ? 1 : 0)) & 0xFF) == 0;
FlagN = (tempint & 0x80) != 0;
if ((tempint & 0x1F0) > 0x090)
tempint += 0x060;
FlagC = tempint > 0xFF;
A = (byte)(tempint & 0xFF);
}
else
{
tempint = value8 + A + (FlagC ? 1 : 0);
FlagV = (~(A ^ value8) & (A ^ tempint) & 0x80) != 0;
FlagC = tempint > 0xFF;
A = (byte)tempint;
NZ_A();
}
}
void Unsupported()
{