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AR# 43607

13.2 NetGen - Simulation models containing negative array index are not supported with ieee_proposed.fixed_pkg


When Running Structural EDK simulation, I receive the following errors in ModelSim:

# ** Error: netgen/par/system_top_timesim.vhd(98228): (vcom-1144) Value -3 is out of std.STANDARD.NATURAL range 0 to 2147483647.
# ** Error: netgen/par/system_top_timesim.vhd(98457): (vcom-1144) Value -3 is out of std.STANDARD.NATURAL range 0 to 2147483647.

These stem from code similar to the following in the post-Translate/MAP and PAR simulation models created from NetGen.


These lines are found iin the signal declaration section:

  signal system_i_aotf_control_0_aotf_control_0_rf_scale_y : STD_LOGIC_VECTOR ( 0 downto -3 );
  signal system_i_aotf_control_0_aotf_control_0_comb_proc_vf_scale_y : STD_LOGIC_VECTOR ( 0 downto -3 );




This occurs when the ieee_proposed.fixed_pkg library is used to introduce negative array indices which NetGen does not support.

For now, this can be worked around by modifying the lines above in the simulation models to use "std_logic_vector1" which is defined in the "simprim_Vpackage.vhd" and supports negative array indices.


AR# 43607
Date Created 08/12/2011
Last Updated 01/27/2015
Status Active
Type General Article
  • ISE Design Suite - 13.1
  • ISE Design Suite - 13.2