How to simulate post synthesis and post place & route design with GHDL

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To simulate post synthesis and post place&route design made with ISE webpack, two library must be used :

  • UNISIM : for Xilinx primitive instance and post synthesis simulation.
  • SIMPRIM : for post place&route simulation.

VHDL sources of this two libraries are provided by Xilinx under $XILINX/vhdl/src/ directory (see xilinx explanation) .

Generate post synthesis/place&route file

To generate Post-synthesis file, just double-click on "Synthesize - XST -> Generate Post-Synthesize simulation Model"

To generate Post-Place & route file, just double-click on "implement design -> Place & Route -> generate Post-place & route simulation Model" and don't forget to select VHDL as preferred language in project properties. The file will be generated in $PROJECT_DIR/netgen/par/top_biled_timesim.vhd.

Compile UNISIM and SIMPRIM with GHDL (on linux)

Sources of libraries can be found in $XILINX/vhdl/src/unisims and $XILINX/vhdl/src/simprims. To compile it, Walter F.J. Mueller made three perl scripts (for more information see his mail):

For ISE 10.x

For ISE 12.x and 13.x

Copy xilinx_vhdl_chop under /usr/local/bin directory, and be sure that /usr/local/bin is under your $PATH. Copy xilinx_ghdl_unisim and xilinx_ghdl_simprim under a directory and make it executable (chmod 755 script_name).

Define $XILINX path before launch xilinx_ghdl_unisim and xilinx_ghdl_simprim to compile libraries.

$export XILINX=/opt/Xilinx/10.1/ISE/

Some files will have compilations error, it's known but not normal !

Compiled libraries will be found in $XILINX/ghdl/unisims/ and $XILINX/ghdl/simprims/.

Simulate with GHDL

Now, we need two files:

  • the testbench wrote in vhdl : testbench.vhd
  • the post-synthesis file wrote in vhdl too : post_synthesis.vhd

First, we have to analyse the design :

ghdl -i --ieee=synopsys -P$XILINX/ghdl/unisim  --warn-no-vital-generic --work=work testbench.vhd post_synthesis.vhd

Then simulate:

ghdl -m --ieee=synopsys -P$XILINX/ghdl/unisim  --warn-no-vital-generic --work=work top_module_name

To simulate post-place and route, do the same but with -P$XILINX/ghdl/simprim option.