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Altera_Forum's avatar
Altera_Forum
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14 years ago

Fixed Point Rounding

Hey guys, I have one more question about fixed point rounding. If you multiply two numbers and have to perform rounding, how would you do that with fixed point? I'm currently round...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Adding MSB of the truncated part has the same effect as what I'm doing. Yes you do not need that long of an adder as I did, I just was showing it for clarity. If you are using the MSB of the truncated part you need an if statement or an adder with a non constant however.

XXXX_XXXX_XXXX_XXXX

truncate to 6+1 bit

XXXX_XXX

+0000_001

Throw away the LSB

Versus

XXXX_XXXX_XXXX_XXXX

truncate 6 MSBs

XXXX_XX

+0000_0(MSB of truncated part)

Use the whole result.

Don't know which one would optimize better. Either one is probably about the same.

/Boris