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INTV: fix overflow flag calculation, fixes checkers and reversi

This commit is contained in:
alyosha-tas 2021-11-23 16:45:28 -05:00
parent 2ea62ffea6
commit e45c9bb398
1 changed files with 18 additions and 7 deletions
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25
src/BizHawk.Emulation.Cores/CPUs/CP1610/CP1610.Execute.cs
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@ -50,6 +50,17 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
);
}
private void Calc_FlagO_Sub(int op1, int op2, int result)
{
bool op1_neg = ((op1 & 0x8000) != 0);
bool op2_neg = ((op2 & 0x8000) != 0);
bool result_neg = ((result & 0x8000) != 0);
FlagO = (
(op1_neg && !op2_neg && !result_neg) ||
(!op1_neg && op2_neg && result_neg)
);
}
private void Calc_FlagS(int result)
{
FlagS = ((result & 0x8000) != 0);
@ -299,7 +310,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
var ones = (dest_value ^ 0xFFFF);
result = ones + 1;
Calc_FlagC(result);
Calc_FlagO_Add(ones, 1, result);
Calc_FlagO_Sub(dest_value, 0, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);
@ -844,7 +855,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
twos = (0xFFFF ^ src_value) + 1;
result = dest_value + twos;
Calc_FlagC(result);
Calc_FlagO_Add(dest_value, twos, result);
Calc_FlagO_Sub(dest_value, src_value, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);
@ -924,7 +935,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
twos = (0xFFFF ^ src_value) + 1;
result = dest_value + twos;
Calc_FlagC(result);
Calc_FlagO_Add(dest_value, twos, result);
Calc_FlagO_Sub(dest_value, src_value, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);
@ -1505,7 +1516,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
twos = (0xFFFF ^ addr_read) + 1;
result = dest_value + twos;
Calc_FlagC(result);
Calc_FlagO_Add(dest_value, twos, result);
Calc_FlagO_Sub(dest_value, addr_read, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);
@ -1578,7 +1589,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
twos = (0xFFFF ^ mem_read) + 1;
result = dest_value + twos;
Calc_FlagC(result);
Calc_FlagO_Add(dest_value, twos, result);
Calc_FlagO_Sub(dest_value, mem_read, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);
@ -1601,7 +1612,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
twos = (0xFFFF ^ addr_read) + 1;
result = dest_value + twos;
Calc_FlagC(result);
Calc_FlagO_Add(dest_value, twos, result);
Calc_FlagO_Sub(dest_value, addr_read, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);
@ -1673,7 +1684,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
twos = (0xFFFF ^ mem_read) + 1;
result = dest_value + twos;
Calc_FlagC(result);
Calc_FlagO_Add(dest_value, twos, result);
Calc_FlagO_Sub(dest_value, mem_read, result);
result &= 0xFFFF;
Calc_FlagS(result);
Calc_FlagZ(result);