Re: [myhdl-list] Starting with MyHDL and trying to do my Cordic Module

[Jan C. <jen...@mu...>]

On 04/07/14 13:33, Christopher Felton wrote:
>    . . .
>
>
>     What is the difference between assigning a value with [:] and
>     without it? All the intbv values need a [:] ?
>
>
> In Python everything is a reference
>
>     x = intbv(0, min=-4, max=4)
>     y = intbv(0, min=-8, max=8)
>     # ...
>     x = 2
>     y[:] = 4
>     assert isinstance(x, intbv)   # will fail
>     assert isinstance(y, intbv)   # will pass
>
> The [:] indicates you are updating the value of the intbv type
> (updating all the bits).  If you didn't do this you would loose 
> the to
> intbv information, because the reference would be assigned to 
> will start
> another type.  But in our HDL we need to know the types we are
> dealing with (we remove some of the dynamicism :)
>
> Yes, all "variable" intbv need "[:] = <new value>".

Thanks, I'd completely missed this point, even though I've paid 
close attention to discussions about the use of signals and variables.

If I had known this three years ago I might well have finished my 
novel processor project by now, and would not be living in a house 
in which all the walls are decorated with skull impressions.

Jan Coombs.