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araneidae
Explorer
Explorer
1,021 Views
Registered: ‎11-22-2016

DSP48E1: is OPMODE=0111000 and CARRYINSEL=001 a valid combination??

During simulation (using QuestaSim) I see the following messages generated:

# ** Warning: OPMODE Input Warning : The OPMODE 0111000 with CARRYINSEL  001 to DSP48E1 instance is invalid.

Is this really an invalid configuration for the DSP48E1, or is there a fault in my simulation library.

According to UG479, this combination has the following significance:

  • OPMODE=011xxxx => Select Z = C
  • OPMODE=xxx10xx => Select Y = -1
  • OPMODE=xxxxx00 => Select X = 0
  • CARRYINSEL=001 => CIN = ~PCIN[47]

I cannot find where in the simulation this message is generated, I've looked at both data/vhdl/src/unifast/primitive/DSP48E1.vhd and data/vhdl/src/unifast/primitive/DSP48E1.vhd, and I can't see anything in UG479 precluding this combination.

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3 Replies
xilinxacct
Professor
Professor
997 Views
Registered: ‎10-23-2018

@araneidae

Many other people are also seeing this... follow this thread... https://forums.xilinx.com/t5/Vivado-High-Level-Synthesis-HLS/Warning-OPMODE-Input-Warning-The-OPMODE-0110X0X-with-CARRYINSEL/m-p/939048

It is not answered definatively, but the previous concensus was it could be ignored.

Hope that helps

If so, please mark as solution accepted. Kudos also welcomed.

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araneidae
Explorer
Explorer
958 Views
Registered: ‎11-22-2016

So let me maybe put this another way.  This is a bug in the simulation library which Xilinx are aware of but have no intention of acknowledging or fixing?

Guessing based on the forums is not a great way forward.

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xilinxacct
Professor
Professor
928 Views
Registered: ‎10-23-2018

@araneidae 

FYI, I got the definative work back from Xilinx to on this...

You can change the "cosim_design" in script.tcl to "cosim_design -disable_depchk" to skip this check.

Yes, these can be safely ignored.

Hope that helps

If so, please mark as solution accepted. Kudos also welcomed. :-)

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