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Altera_Forum
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8 years ago

Fully Synthesizable Fix Point package

Hi,

Great- I'v just learned how to use fully synthesizable floating point arithmetic calculation (using MegaFunction/IP cores). Now, how can I implement fully synthesizable Fix point calculation? I couldn't find any MegaFunction/ IP cores for that purpose…

Thanks a lot,

Idan

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    Fixed point aritmetic is just integer arithmetic, offset by 2^n. So no special IP is needed.

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    H;

    Thanks alot for your quick response!

    Where can I find an example for this kind of code?

    Thanks againe...

    Idan
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    in VHDL - its simple, especially if you use the fixed point package: 

    
use ieee.fixed_pkg.all;
....
signal a : sfixed(7 downto -8); -- 1 sign bit, 7 integer bits, 8 fraction bits - ie. integer offset by 2^8
signal b : sfixed(15 downto -16);
...
b <= a*a;

    this can all be done with the numeric_std package, but you need to keep track of the offset yourself.
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    --- Quote Start ---

    Does the "fixed_pkg" is fully synthesizable?

    --- Quote End ---

    Yes. While full support only comes with Quartus Pro 16.0, you can use the '93 compatible version for compilation.

    Otherwise all of this can be done with numeric_std, which is compatible with all versions of quartus.