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Altera_Forum's avatar
Altera_Forum
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17 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
17 years ago

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They are available in MegaFunction, see my previous post.

Regarding the sign extension point, I don't see that it works without additional logic, provided, that the full multiplier resolution (e.g. 9x9 = 18) with Cyclone hardware multipliers shall be utililzed. As an example 0x1ff * 0x1ff should have a result of 0x3ffff (-1) in signed arithmetic and 0x3fc01 (261121) in unsigned.

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Whoops:

-1 x -1 = 1

0x1FF x 0x1FF = 0x3F801 when unsigned and 0x00001 when signed