Re: [myhdl-list] how to make list of unequal-sized signals

[David B. <da...@be...>]

Hi all,

that is indeed exactly what I want to do. I do not want instantiate a memory like iface, but rather bunch of individual signals, which will be properly linked. 

using this construct:
multout = [Signal(intbv(0, min=de.min*coeff, max=de.max*coeff)) for coeff in coeffs]

outside of the yield functions works exactly as expected, i.e. it generates tons of signals. Problem is, that I use multout as follows:

    @always_comb
    def outdat():
        totsum = 0
        for i in range(len(coeffs)):
            totsum += multout[i]
        qe.data.next = totsum

and when multout is inside any decorated block it tries to instantiate memory-like array (as properly stated in docs), which i'd like to avoid and instead generate 'on-fly' totsum = resize(multout[0], totsum'length)+resize(multout[1], totsum'length)+....

which would permit me to take control over length of multout (which is an output of multiplier, hence I'd like to use minimum amount of bits to implement it to control fpga resources)...






Christopher Felton <chr...@gm...> writes:

>> this does not seem to be convertible, as the signals in the array
>> have different lengths
>>
>> multout = [Signal(intbv(0, min=de.min*coeff, max=de.max*coeff)) for
>> coeff in coeffs]
>
> You can't do this, in hardware if they are all different
> types they would need to be mapped to some non-homogeneous
> structure (i.e. not memory).
>
> What I would do if first find the min and max in your
> coefficients and create the coefficient array
> (list-of-signals) from the overall collection's min and
> max.  Then you have a structure that can be mapped to
> to a memory if needed.
>
> If that is not desired, you don't have much choice but
> to individually select the different size `coeff`.  Note,
> if you use the ROM [1] structure (tuple-of-ints) it will
> use the minimal hardware you desire.
>
> Regards,
> Chris
>
>
> [1] 
> http://docs.myhdl.org/en/stable/manual/conversion_examples.html#rom-inference
>
>
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