private void ExecuteLogicalOperation(LogicalOperationType operation)
{
// Perform the logical operation using our host CPU
int result = 0;
switch (operation)
{
case LogicalOperationType.And:
result = ALULeftBuffer & ALURightBuffer;
break;
case LogicalOperationType.Or:
result = ALULeftBuffer | ALURightBuffer;
break;
case LogicalOperationType.Xor:
result = ALULeftBuffer ^ ALURightBuffer;
break;
}
// Truncate the result to 8 bits and send it to the internal data bus.
InternalDataBus = (byte)result;
// Compute all flags
// Flags bit 7 - SF flag - Set if the 2-complement value is negative. It's simply a copy of the most signifcant bit.
// Flags bit 5 - YF flag - A copy of bit 5 of the result.
// Flags bit 3 - XF flag - A copy of bit 3 of the result.
F = (byte)(result & B10101000);
// Flags bit 6 - ZF flag Set if the result is zero.
if (result == 0)
{
F |= B01000000;
}
if (operation == LogicalOperationType.And)
{
// Flags bit 4 - HF flag is set
F |= B00010000;
}
else if (operation == LogicalOperationType.Or || operation == LogicalOperationType.Xor)
{
// Flags bit 4 - HF flag is reset
}
// Flags bit 2 - PF flag - This flag is also used with logical operations and rotate instructions to
// indicate the resulting parity is Even. The number of 1 bits in a byte are
// counted. If the total is Odd, ODD parity is flagged (P = 0). If the total is
// Even, EVEN parity is flagged (P = 1).
if (numberOfBitsInByteParityTable[result])
{
F |= B00000100;
}
// Flags bit 1 - NF flag is reset
// Flags bit 0 - CF flag is reset
}
private void ExecuteLogicalOperation(LogicalOperationType operation)
{
// Perform the logical operation using our host CPU
int result = 0;
switch (operation)
{
case LogicalOperationType.And:
result = ALULeftBuffer & ALURightBuffer;
break;
case LogicalOperationType.Or:
result = ALULeftBuffer | ALURightBuffer;
break;
case LogicalOperationType.Xor:
result = ALULeftBuffer ^ ALURightBuffer;
break;
}
// Truncate the result to 8 bits and send it to the internal data bus.
InternalDataBus = (byte)result;
// Compute all flags
// Flags bit 7 - SF flag - Set if the 2-complement value is negative. It's simply a copy of the most signifcant bit.
// Flags bit 5 - YF flag - A copy of bit 5 of the result.
// Flags bit 3 - XF flag - A copy of bit 3 of the result.
F = (byte)(result & B10101000);
// Flags bit 6 - ZF flag Set if the result is zero.
if (result == 0) F |= B01000000;
if (operation == LogicalOperationType.And)
{
// Flags bit 4 - HF flag is set
F |= B00010000;
}
else if (operation == LogicalOperationType.Or || operation == LogicalOperationType.Xor)
{
// Flags bit 4 - HF flag is reset
}
// Flags bit 2 - PF flag - This flag is also used with logical operations and rotate instructions to
// indicate the resulting parity is Even. The number of 1 bits in a byte are
// counted. If the total is Odd, ODD parity is flagged (P = 0). If the total is
// Even, EVEN parity is flagged (P = 1).
if(numberOfBitsInByteParityTable[result]) F |= B00000100;
// Flags bit 1 - NF flag is reset
// Flags bit 0 - CF flag is reset
}
