Wierd result when inverting an input

[Acetronics2]

BTW,

I remember Darrel had written a post about this kind of behaviour.
he used a "!!" to get rid of the problem.

does somebody remember where it was shown ???

Alain

[Tabsoft]

That post would be interesting to read.
I don't see how it would alleviate the issue.
I think without an interim step to force the assignment to a bit type variable it will perform the operation as a byte.

I might take a look through the PBP library macros for Logical and bitwise NOTs to see if there is another macro that would hand the situation. If there is, it would be a matter of what syntax would cause the compiler to pick that macro instead.

[xpa999]

It would seem that the simple way around this is:

Report = 48 + !Mypin

Wouln't that force
Picbasic to evaluate Report as a byte, not as a bit?

[Tabsoft]

No, not really.
That has been the point of this discussion.

We would not want PBP to do the interim calculations as a byte, we would want PBP to do them as a bit.

The issue is that in this statement "Report = 48 + !Mypin"
Report is a byte variable, 48 will be treated as a constant and Mypin is a bit.
Sounds good so far, but, when PBP looks at this statement it will treat the !Mypin as a byte output in the calculation step.
It does this because "Report" on the left side is a byte variable.

What we want is if Mypin = 0 then Report = 49; If Mypin = 1 then Report = 48.

But here is what happens.

Pseudocode for the PBP ASM Macros used for the following Statement: Report = 48 + !Mypin

Step 1. Perform a Logical NOT on Mypin.
    Clear the W register (Set it to 0)
    If Mypin is a zero then 
        Store 255 decimal in the W register  'This is because Report will ultimately get the value, so PBP starts treating all the output variables as bytes
    else
        Store 0 in W register
    endif
    Move W register to a temporary "byte" variable T1
    
Step 2. Add 48 to temporary "byte" variable T1
        
Step 3. Move Temporary "byte" variable T1 to "byte" variable Report

So if you start with Mypin = 0, then

Step 1. T1 = 255
Step 2. T1 = 255 + 48 = 47   ' This is because a byte variable is unsigned in PBP
Step 3. Report = 47 'We wanted Report to equal 49 not 47

If you start with Mypin = 1
Step 1. T1 = 0
Step 2. T1 = 0 + 48 = 48
Step 3. Report = 48 'This is what we wanted.

So the issue as I can see is that to perform this logic as we "want" it to work, you need to manually perform an interim step
and store the current value of Mypin in a "bit" variable. Then perform a logical NOT on the "bit" variable. Then add 48 and the "bit" variable
and store the answer in report.

myBit var bit
Mypin var PORTB.6
Report var byte

myBit = Mypin
myBit = !myBit
Report = 48 + myBit

This works.

[Dave]

And the answer is....
Mypin var Portb.6
Report var byte

Report = 48 + (Mypin ^ 1)

There is NO need to be changing variable types. Mypin just needs to be inverted. So why not invert it as if it is a bit. Wow all of this typing for something so simple......