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Kyle's avatar
Kyle
Icon for New Contributor rankNew Contributor
7 years ago

How to Remove Constant Multiplication Optimization?

Hi all,

I am looking to disable the optimization done when multiplying by a constant. I have DSP blocks available that I want to reuse instead of having the operation mapped to logic. I am using Quartus II 15.0.

I've:

  • tried calling an IP block with the generic "lpm_hint => "DEDICATED_MULTIPLIER_CIRCUITRY=YES, MAXIMIZE_SPEED=0","
  • looked through the options under "Assignments -> Settings -> Compiler Settings -> Advanced Settings"
  • searched through the forums.

All to no avail. Any help is appreciated. Thanks!

2 Replies

  • ak6dn's avatar
    ak6dn
    Icon for Regular Contributor rankRegular Contributor
    7 years ago

    If the block is written to be fully general at the Verilog/VHDL level, why do you care that in a particular instance, when you feed it constants, that Quartus does implementation optimization? Each time you instantiate the block, Quartus will look at all the inputs/outputs, and if inputs are constants, it will optimize around that. And for unused outputs the logic will be discared (by default, can be suppressed). Why do you care if Quartus is doing this?

  • Vicky1's avatar
    Vicky1
    Icon for Regular Contributor rankRegular Contributor
    7 years ago

    Hi,

    Could you please provide the below information?

    device used

    IPs used

    are you using Qsys or IP Catalog?

    any screen shot

    Thanks,

    Vikas