Passing array from system verilog to VHDL

Question

I have a code in VHDL which requires an array of elements as generic. COEF_LIST : coef :=(0,0,1,1,2,-2,1,-2,1)

How do I send new set of COEF_LIST from my system verilog testbench to VHDL entity?

Generic in VHDL is same as parameter in verilog.

I declared coef as

  parameter  real COEFF[8:0] = '{0,0,1,1,2,-2,1,-2,1};

in system verilog.

I tried passing using (in my verilog testbench)

 vhdl_entity  #(
                 .COEF_LIST(COEFF)
               )

I get the following error

                 **.COEF_LIST(COEFF)
                                |

ncelab: *E,CFIGTC (./vhdl_entity_tb.vams,41|36): VHDL generic vhdl_entity.COEF_LIST (../views/rtl/vhdl_entity.vhd: line 34, position 14) type is not compatible with Verilog. irun: E,ELBERR: Error during elaboration (status 1), exiting.*

This doesn't work. How do I make it compatible with VHDL? I am using incisiv 13.20.008 version

Could anyone please suggest what to do?

Can you give more details of what goes wrong? (Preferably by editing your post) — Ganesh Sittampalam
– Ganesh Sittampalam, Commented Jun 3, 2014 at 22:16
Try simplifying the problem by setting a default argument on the VHDL entity to see if that works. You have declared as an array of real but the VHDL elaborator may be seeing the array as a list of integers. See what happens when you add decimal points to the numbers. — Kevin Thibedeau
– Kevin Thibedeau, Commented Jun 4, 2014 at 4:24
Post the declaration of the VHDL entity (just the generic would be enough, no ports) to better show what's going on. — Tudor Timi
– Tudor Timi, Commented Jun 4, 2014 at 7:56

Tudor Timi · Accepted Answer · 2014-06-04 07:55:52Z

2

Seems like you declared your COEF_LIST as an array of integers in VHDL, whereas you are trying to pass an array of reals from SystemVerilog. Try changing to:

parameter int COEFF[8:0] = '{0,0,1,1,2,-2,1,-2,1};

answered Jun 4, 2014 at 7:55

Tudor Timi

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2 Comments

user1155120 Over a year ago

Assuming COEF_LIST : coef :=(0,0,1,1,2,-2,1,-2,1) is a generic declaration in a generic interface list, the type declaration for coef is not knowable from the information present. Your answer works only if the array type coef has a base type of integer and incisiv provides implicit type conversion. This seems like a type incompatibility issue between two language domains requiring fixes in both domains.

Tudor Timi Over a year ago

@DavidKoontz Hence the "seems like" in the answer and not "because".

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