Parameterised wire select

[louis574]

When parameterising the lsb cell of a bus select it does not select the correct bits (or width)

1. Open an ISSIE sheet
2. initialise a parameter 'x'
3. make an input and an output - both with bit width parameterised by x - ill refer to them as 'in' and 'out'
4. make a new 1 bit output - ill refer to it as 'msb'
5. make a bus select - with bit width 1 and lsb select 'x-1' - and connect the end to 'msb'
6. connect 'in' to 'out' and the bus select

Expected behavior
The expression in the bus select is correctly evaluated for all parameter values and selects the most significant bit of the input (with a width of 1).

Actual behaviour
The parameter expression is evaluated - but this value is actually copied into the bit width cell - and the lsb cell gets evaluated to 0 - -leading to incorrect bits selected.

Screenshots

here x is my parameter - i had the bitwidth set to a constant 1 but it was changed by issie when i changed the value of parameter x.
In this example I set x to 8. as you can see the bitwidth is becomes what the lsb cell should be evaluated to (7) and the lsb is evaluated ot 0 .

Desktop (please complete the following information):

• OS: Windows 11
• Version 5.10.3

[tomcl]

Thanks for this. Parameters in Issie are currently in development and this bug will be fixed when we next look at that code.

Workaround: don't use parameters!

[tomcl]

I have fixed an error in non-parametrised busselects that was critical.

That fix resolves this. Mostly.
(1) if the bus-select lsb in the creation dialog is set to x-1 there is no UI error, and the actual value taken is 0. In this case the bug remains.
(2) if the bus-select lsb is set to x-1 from the properties box the parameter works in simulation as expected.

TODO - fix the creation dialog box either to error on parameter expressions, or to correctly record them.