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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

signed/unsigned multipliers

I can't seem to find a way to instantiate a multiplier that will dynamically select between signed and unsigned multiplication. This is on a Cyclone II, but applies to other parts as well. Read...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

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Thanks Tricky.

It does really work.

So in principle you are doing what altera never tell us....as usual.

To use unsigned, given a signed input:

1) double extend input width using sign extension

2) truncate output to double inputwidth

Very useful discussion.

--- Quote End ---

IMO, Tricky side stepped the real issue. I already pointed out that the lower bits would be identical, so obviously widening the input would "solve" the problem, at a quadratic cost!!

You (Kaz) provided an actual useful workaround. I'm still working with support to get the original bug fixed.

Tommy