ASIC/FPGA Design and Verification Out Source Services

IP TTL filter digital design, implemented in VHDL.

1. This project implements an IP TTL filter in hardware. If an IPV4 packet is identified, the DUT checks its TTL field. Based on previous values of TTL in former packets, the machine decides if the packet is spoofed or not. The main page of this project.;


2. This page describes the simulation script: compile and run simulation is done using the free VHDL simulator: GHDL.


3. To compile:                    ./ghdl_cmp.unx
   To simulate with VCD waves:    ./ghdl_cmp.unx vcd
   To simulate without VCD waves: ./ghdl_cmp.unx run
   


4. The script tries to figure out on each stage if the job ended okay. If not it stops and prints some info.
   
   #!/bin/bash
   
   #clear - removes the compilation directory before start
   if [ "$1" = "clear" ] ; then
     #clear any former compilation results
     rm -fr work
     shift
   fi
   
   if [ -d "work" ] ; then
     echo "work directory exists"
   else
     mkdir work
   fi
   
   skip="f"
   if [ "$1" = "vcd" ] ; then
     skip="t"
   else
     if [ "$1" = "run" ] ; then
       skip="t"
     fi
   fi
   
   if [ "$skip" = "f" ] ; then
     ghdl -i --workdir=work --ieee=synopsys tb_rx_top.vhd rx_top.vhd ip_ttl_extract.vhd ip_ttl_control.vhd mem_model.vhd <& cmp.log
     grep vhd cmp.log < /dev/null
     if [ $? -eq 0 ] ; then
       echo "compilation failed"
       cat cmp.log
       exit 1
     else
       ghdl -m --workdir=work --ieee=synopsys tb_rx_top
     fi
     grep "simulation ended okay" ghdl.log
     if [ $? -ne 0 ] ; then
       echo "test failed"
     fi
   fi
   
   ghdl_run="./tb_rx_top --stop-time=100us --assert-level=error"
   if [ "$1" = "vcd" ] ; then
     ghdl_run=$ghdl_run" --vcdgz=ghdl.vcd.gz >& ghdl.log"
     eval $ghdl_run
     grep "simulation ended okay" ghdl.log
     if [ $? -ne 0 ] ; then
       echo "test failed"
     fi
   fi
   if [ "$1" = "run" ] ; then
     eval $ghdl_run" >& ghdl.log"
   fi
   



5. I have also prepared a Makefile for the project. Makefiles are much more easier to maintain, and add some c code to enhance the test-bench:
   GHDL c interfaces. The makefile can be downloaded from: Makefile.gz
   The makefile is divided to three parts:
   
   
   1. The first part is used to declare variables for the makefile: flags and compilers.
      #variables
      CC = gcc
      CFLAGS = -c -g
      #-MD
      SHELL := /bin/bash
      
      GG = ghdl
      ...
      
   2. The second one are options to run simulation, with or without VCD wave record.
      ...
      .PHONY : run
      run :
        ./tb_rx_top $(RUN) |& tee ghdl.log
      .PHONY : vcd
      vcd :
        ./tb_rx_top $(RUN) $(VCD) |& tee ghdl.log
      
   3. The last one is compilation. Note this step involves c code compilation (gcc) and VHDL compilation (ghdl).A few lines of the compilation are listed below:
      .PHONY : all
      all : pkg g_rand.o work exe
      
      .PHONY : exe
      exe : work
      $(GG) $(EFLAGS) -Pmy_lib --workdir=work --ieee=synopsys tb_rx_top
      
      .PHONY : work
      work : my_package.vhd ...
      



6. For more details on this project, please send an e-mail and put in the subject:
   IP TTL filter.