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V2.1i COREGEN, VIRTEX, FOUNDATION: Invalid EDIF with shorted nets produced for Virtex Dual & Single port Block memory on first iteration / Foundation simulator "duplicate net" errors


Record #7237

Product Family: Software

Product Line: Coregen

Product Part: Coregen

Product Version: 2.1

Problem Title:
V2.1i COREGEN, VIRTEX, FOUNDATION: Invalid EDIF with shorted nets produced for Virtex Dual & Single port Block memory on first iteration / Foundation simulator "duplicate net" errors



Problem Description:
Urgency: hot

General Description:
After starting up a CORE Generator session, if either a Virtex Dual Port
or Single Port Block Memory is the first core you generate, the EDIF
implementation netlist may be invalid. In some cases, there may be nets
that are shorted together. For example, an address bit may be shorted
with the CLK signal:

     (net (rename N3 "addr<1>")
      (joined
	(portRef addr_1_)
	(portRef ADDRA_1_ (instanceRef BU0))
	(portRef ADDRB_1_ (instanceRef BU0))
      )
     )	    (net (rename N2 "clk")
      (joined
	(portRef clk)
	(portRef CLKA (instanceRef BU0))
	(portRef CLKB (instanceRef BU0))
      )
     )
     (net (rename N2 "addr<0>")
      (joined
	(portRef addr_0_)
	(portRef ADDRA_0_ (instanceRef BU0))
	(portRef ADDRB_0_ (instanceRef BU0))
      )


In the snippet above, addr<0> and CLK are shorted together as a result of
both being renamed to "N2". This can cause "duplicate net" errors
when simulating a design containing such a core in Foundation.


Solution 1:

The problem is only seen when the core is generated in GUI mode. Generating the core in batch mode does not show this problem.

To regenerate the core in batch mode, read in the .XCO file by doing a
File->Execute Command File and specify the .XCO file as input.



Solution 2:

The problem has been only seen when you generate a Dual Port or Single Port
Virtex Block RAM immediately after starting up the CORE Generator.
You must regenerate the respective core a second time within the same
session to get a valid EDIF netlist.




End of Record #7237 - Last Modified: 08/31/99 08:40

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