What should happen with bitwise OR with two different variable sizes

[kcsl]

I've been going crazy trying to find a bug in my program and I found this.

dim dblOutput     as dword = $700
dim bytValue      as byte  = $FF

    dblOutput = dblOutput | bytValue

I expected dblOutput to be $7FF but it's coming out as $FF

Can probably code around this but which is the correct answer?

Actually, changed it to dblOutput = dblOutput + bytValue and that works, so not a problem for me in this instance.

Regards,
Joe

[top204]

That is my mistake in the logic of the code generator. It is reacting it as if only the first 8-bits need to be ORed, so it is clearing the rest of the Dword variable, as it would do if it was an ANDing.

This is a "day one" anomaly, that has been with the compiler since I first added Dword variables about 20 years ago! It also effects the Xor logic.

I am busy correcting them now for the up and coming update.

Thanks for spotting it Joe, and I will check out the other boolean mechanisms for different variable types, where the second operand is a smaller type.

You can do the code:

dblOutput.Byte0 = dblOutput.Byte0 | bytValue

And it will do the correct logic and perform the ORing on the first 8-bits only of dblOutput, and will not be effected by the up and coming correction.