How do i use the NOT component ?

I am trying to invert xdir (and Y and Z) using NOT. I have to use NOT as invert isn't available in the GPIO_PI_HAL component. Problem is I don't know what I'm doing, the instructions don't seem to have many example and searching NOT finds plenty but not related to NOT. I've included below my best guess with some comments as to what I think is happening;

#load the component
loadrt not

#start an instance of not ??
#not.0 is already used in the sample HAL file that I've started with (for a probe that i'm not using)
addf not.1 servo-thread

#create a signal called notxdir for the purposes of inverting stepgen.0.dir. Not really sure i need to do this?
net notxdir stepgen.0.dir not.1.in

#then create the xdir signal taking the output of not.1 and send it to pin-24 ???
net xdir not.1.out hal_pi_gpio.pin-24-out

That thread seems to conclude by using 'invert' which doesn't work with GPIO_PI_HAL.

setp parport.0.pin-08-out-invert true
net xenable => parport.0.pin-08-out

Using NOT gets a mention but the syntax doesn't look correct (???? there's not net or addf on the second line) and i don't think anyone pursued it.

net xenable => not.0.in
not.0.out => parport.0.pin-08-out

Maybe best to post your hal file.

I think i just made it work

addf not.1 servo-thread
net xenable not.1.in
net x-not-enable not.1.out => hal_pi_gpio.pin-29-out

yes, RPI4 using the GPIO. Of course the X and Y didn't actually need reversing after all that. I was pressing left on the keyboard and the table moved right, but I now think that is correct (cutting tool moves left relative to work piece) ?

I needed to reverse the enable pin and the Z axis anyway, so nothing lost.

I'll switch from the GPIO to a MESA 7i96 at some point soon, just want to make some chips before spending more money.

Yes, by convention direction is that of tool motion relative to work piece.

One thing you need to be aware of and possibly be careful with when using a hal component like "not" is that the order your hal components are addf-ed to the threads determines the order which they are processed. If your components are processed in a bad order it can add a thread cycle or two delay in response to an input or output.