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Altera_Forum
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15 years ago

Huge reduce in logic usage when megafunction is instantiated

Hi guys, I've been playing around with the floating point megafunctions, and I tried to implement it on hardware. I noticed that when I compiled a floating point adder on its own, it used arou...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

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Simply ALTFP_ADD_SUB can't reduce it's LE requirement to said 400 LEs without omitting a considerable part of it's function, e.g number of calculated bits. So rbugalho obviously assumed, you must have removed part of it's arithmetic function by not completely connecting all in- and outputs of the Megafunction. I agree that it's the only plausible explanation for your results.

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Thanks for your reply, FvM. But how do I check whether I omitted a part of it's function?

I just used the .cmp files to instantiate it and assigned all the signals to the Port map.

I assigned values to the inputs into the megafunction by code and it manages to calculate the correct result, so I guess it should be functional.

Thanks again,

Chris