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ZAhma1's avatar
ZAhma1
Icon for New Contributor rankNew Contributor
6 years ago
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ALTERA_FP_FUNCTIONS Single Precision Multiplier doesn't seem to support subnormal numbers

I am trying to use a Single Precision Floating Point multiplier as generated by QSys in Quartus Prime 16.1.2. We are using an Arria 10 device so the option I have is to use the ALTERA_FP_FUNCTIONS mo...
  • AnandRaj_S_Intel's avatar
    AnandRaj_S_Intel
    6 years ago

    Yes, I got the problem.

    However Altera floating-point IP cores do not support denormal/subnormal number inputs. If the input is a denormal value, the IP core forces the value to zero and treats the value as a zero before going through any operation.

    Hence we are seeing output zero.

    Regards

    Anand

AnandRaj_S_Intel's avatar
AnandRaj_S_Intel
Icon for Regular Contributor rankRegular Contributor
6 years ago

Hi Ahmad,

You have to check the output of ALTERA_FP_FUNCTION when valid signal is high.

you can check with example design from user guide

Please share you design or image.

Regards

Anand

ZAhma1's avatar
ZAhma1
Icon for New Contributor rankNew Contributor
6 years ago

Hi Anand,

As you may be aware with most FPGA IPs, there is no data valid signal. You just have to wait the suggested number of cycles and hope the output is correct.

I've created a sample project with the IP in question and also added a testbench which will run the problem cases. I'll attach them here.