struct

Help/counter2/.gitignore

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+runs
+.vscode
+workspace.code-workspace
+*.pyc

Help/counter2/README.md

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+# Aim of the project
+
+This project gives an example of the desired structure for a *Verilog* project. It is composed of the following folders:
+
+- build : Contains (tcl) scripts to build a Vivado or other project out of this arborescence.
+- constraints : Contains the constraints (if needed) for the project.
+- ip : Contains external dependencies of the project. This folder is used for commodity only in order to simplify test and verification scripts. Its contents should be populated by a build script (or manually copied in some cases). Each subdirectory corresponds to a dependency in the same format as the current document. For old projects, at least *src* directory should be present. Normally, it should not be under version control. 
+- runs : Contains all temporary files built by the runs of different tools (e.g. simulation, verification etc.). It might have a substructure, depending on the tool. It **should not** be under version control.
+- scripts : Contains different scripts related to the project. Typical examples - launch simulation or verification. The scripts might be in shell, makefile, tcl etc. A preference for tcl should be considered.
+- src : Contains source files for the project. It has subdirectories corresponding to the HDL language used (Verilog, VHDL, Migen, Amaranth, etc)
+- tests : Contains testbenches  for the project. It has subdirectories corresponding to the used tool (cocotb, verilog, verilator, etc). For *python*-based tools, the corresponding structure should allow test discovery using pytest (file names containing *test* and functions containing *test*).
+- verification : Contains scripts and files for formal verification.
+- other folders that are related to the editor and that probably should not be under version control. 
+
+The project should be under version control (e.g. *git*) and have corresponding *.gitignore* specifications. 
+
+The root of the project shall only contain:
+
+- a README.md file that gives the description of the project.
+- *.gitignore* or similar files, related to the version control.
+- a *Makefile* or a launcher script named *project* that have arguments allowing to run different tools. If present, it must contain at least the argument *clean* that will delete all elements from the *run* folder (maybe also all non-vcs tracked files).
+- Editor-related files, e.g. *workspace.code-workspace* for VSCode. These files should not be under version control.

Help/counter2/project.bat

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+@tclsh scripts\project.tcl %* 

Help/counter2/scripts/gtk_wave_all_signals.tcl

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+puts "Starting TCL script"
+#set path test1b_tb
+#gtkwave::forceOpenTreeNode $path
+set nfacs [ gtkwave::getNumFacs ]
+puts "There are $nfacs signals"
+set l [list]
+
+for {set i 0} {$i < $nfacs } {incr i} {
+    set facname [ gtkwave::getFacName $i ]
+	set numdots  [ expr {[llength [split $facname .]] - 1}]
+#	puts "$numdots"
+    if {$numdots == 1} {
+      lappend l "$facname"
+      puts "Added signal $facname"
+	}
+}
+
+set num_added [ gtkwave::addSignalsFromList $l ]
+gtkwave::setZoomRangeTimes [ gtkwave::getMinTime ] [ gtkwave::getMaxTime ]
+puts "Start time [ gtkwave::getMinTime ] end time: [ gtkwave::getMaxTime ]"

Help/counter2/scripts/project.tcl

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+# Tcl launcher script for the project
+namespace eval project_launcher {
+
+    # Help information for this script
+    proc print_help {} {
+        variable script_file "project.tcl"
+        puts "\nDescription:"
+        puts "Perform actions related to this project.\n"
+        puts "Syntax:"
+        puts "$script_file"
+        puts "$script_file \[action\] \[args\]"
+        puts "Usage:"
+        puts "Name                   Description"
+        puts "-------------------------------------------------------------------------"
+        puts "\[action\]             Determine the action to be performed. Default value: help\n"
+        puts "                       Current actions: help, clean, sim, verify, test\n"
+        puts "\[args\]               Arguments related to the action.\n"
+        puts "                       --root <dir> changes the root reference for the project.\n"
+        puts "-------------------------------------------------------------------------\n"
+        exit 0
+    }
+
+    proc do_clean { root_dir } {
+        variable dir "$root_dir/runs"
+
+        puts "Cleaning all files in directory $dir...\n"
+
+        # Checking if the folder is empty to avoid error
+        if {[catch { glob "$dir/*" } result] != 1} {
+            file delete -force -- {*}[glob "$dir/*" ]
+        }
+    }
+
+    proc do_sim_icarus { root_dir verbose } {
+
+        # Checking if the folder is empty to avoid error
+        if {[file exists "$root_dir/scripts/run_iverilog.tcl"] == 1} {
+            #global root_dir_loc $root_dir
+            #source $root_dir/scripts/run_iverilog.tcl
+            try {
+                set results [exec tclsh $root_dir/scripts/run_iverilog.tcl $root_dir ]
+                set status 0
+            } trap CHILDSTATUS {results options} {
+                set status [lindex [dict get $options -errorcode] 2]
+            }
+
+            if {$status != 0} {
+                puts "Problem running the script :"
+                puts $results
+                return
+            }
+
+            if {[expr $verbose]} {
+                # output the result of the execution
+                puts $results
+            }
+
+        } else {
+            puts "The script run_iverilog.tcl does not exist in $root_dir/scripts"
+        }
+    }
+
+    proc do_sim_pytest { root_dir verbose } {
+
+        exec pytest $root_dir/tests/ >@stdout 2>@stderr
+    }
+
+    proc do_formal { root_dir } {
+        # We suppose that the sby file is meant to be run from the inside of the folder
+        # hence we cd there
+        if {[file pathtype $root_dir] != "absolute"} {
+            set root_dir "../$root_dir"
+        }
+        #set root_dir [file normalize $root_dir]
+        cd verification
+        #variable fname [glob -nocomplain $root_dir/verification/*.sby]
+        variable fname [glob -nocomplain *.sby]
+
+        if {[llength $fname]} {
+            set fname [lindex $fname 0]
+            puts "Using $fname file..."
+            exec sby -f $fname --prefix $root_dir/runs/verification/counter >@stdout 2>@stderr
+        } else {
+            puts "There are no .sby files present..."
+            cd ..
+            return
+        }
+        cd ..
+    }
+
+    proc main {} {
+
+        variable root_dir
+        # Set the reference directory to where the script is
+        #set root_dir [file dirname [info script]]
+
+        # Set the reference directory for source file relative paths (by default the value is script directory path)
+        set root_dir "."
+
+        # Use origin directory path location variable, if specified in the tcl shell
+        if { [info exists ::root_dir_loc] } {
+            set root_dir $::root_dir_loc
+        }
+
+        variable action "help"
+
+        variable verbose false
+
+        if { $::argc > 0 } {
+            for {set i 0} {$i < $::argc} {incr i} {
+                set option [string trim [lindex $::argv $i]]
+                switch -regexp -- $option {
+                    "--root"   { incr i; set root_dir [lindex $::argv $i] }
+                    "--help"         { print_help }
+                    "help"         { print_help }
+                    "clean"     { set action "clean" }
+                    "sim"       {incr i; set action "sim_[lindex $::argv $i]" }
+                    "--verbose" { set verbose true }
+                    "-v"        { set verbose true }
+                    {pytest|cocotb|test}    {set action "pytest"}
+                    {formal|verify|verification}  {set action "formal"}
+                    default {
+                        if { [regexp {^-} $option] } {
+                            puts "ERROR: Unknown option '$option' specified, please type '$script_file -tclargs --help' for usage info.\n"
+                            return 1
+                        }
+                    }
+                }
+            }
+        } else {
+            print_help
+        }
+
+        puts "Script started. The root dir is $root_dir. The action is: $action\n"
+
+        switch -regexp -- $action {
+            "clean"   { do_clean $root_dir }
+            {sim_icarus|^sim_$|sim_iverilog} { do_sim_icarus $root_dir $verbose}
+            {sim_cocotb|pytest} { do_sim_pytest $root_dir $verbose}
+            "formal" { do_formal $root_dir}
+        }
+
+
+
+    }
+
+
+
+
+    main
+
+}

Help/counter2/scripts/run_iverilog.tcl

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+# Tcl script for iverilog simulation
+namespace eval sim_iverilog {
+
+
+  # Help information for this script
+  proc print_help {} {
+    variable script_file "run_iverilog.tcl"
+    puts "\nDescription:"
+    puts "Runs the iverilog simulation.\n"
+    puts "Syntax:"
+    puts "$script_file"
+    puts "$script_file \[action\] \[args\]"
+    puts "Usage:"
+    puts "Name                   Description"
+    puts "-------------------------------------------------------------------------"
+    puts "\[action\]             Determine the action to be performed. Default value: help\n"
+    puts "                       Current actions: help, clean\n"
+    puts "\[args\]               Arguments related to the action.\n"
+    puts "                       --root <dir> changes the root reference for the project.\n"
+    puts "-------------------------------------------------------------------------\n"
+    exit 0
+  }
+
+
+  proc main {} {
+
+    variable root_dir
+    # Set the reference directory to where the script is
+    #set root_dir [file dirname [info script]]
+
+    # Set the reference directory for source file relative paths (by default the value is script directory path)
+    set root_dir "."
+
+    if { [info exists ::root_dir_loc] } {
+      set root_dir $::root_dir_loc
+    }
+
+    if { $::argc > 0 } {
+      set root_dir [lindex $::argv 0]
+    }
+
+    puts "Starting simulation using iverilog. The root dir is: $root_dir"
+
+    #   variable root [file dirname [file normalize [info script]]]
+    #   variable root [file dirname [file dirname [info script]]]
+    variable root $root_dir
+
+    variable source_path $root/src/verilog
+
+    variable sources {counter.v}
+
+    variable tb_path $root/tests/verilog
+
+    variable test_benches {counter_tb.v}
+
+    proc append_path {root list} {
+      set l {}
+      foreach f $list {
+        lappend l $root/$f
+      }
+      return $l
+    }
+
+    variable sources_full_path [append_path $source_path $sources]
+    variable tb_full_path [append_path $tb_path $test_benches]
+
+    variable output_dir $root/runs/sim/iverilog
+
+    variable additional_options "-D VCD_DUMP"
+
+    proc run_sim {tb} {
+      set name [file rootname $tb]
+      puts "Running test bench $name"
+
+      puts "Cleaning files..."
+
+      #    file delete [glob -nocomplain $sim_iverilog::output_dir/*]
+
+      puts "Recreating path..."
+
+      file mkdir $sim_iverilog::output_dir
+
+      set iverilog_args "$sim_iverilog::additional_options -g2012 -Wall -I $sim_iverilog::source_path -Y .sv -y $sim_iverilog::source_path -o $sim_iverilog::output_dir/$name.vvp $sim_iverilog::tb_path/$tb $sim_iverilog::sources_full_path"
+
+
+      try {
+        set results [exec iverilog {*}$iverilog_args]
+        set status 0
+      } trap CHILDSTATUS {results options} {
+        set status [lindex [dict get $options -errorcode] 2]
+      }
+
+      if {$status != 0} {
+        puts "Problem running iverilog :"
+        puts $results
+        return
+      }
+
+      # output iverilog result
+      puts $results
+
+      set cwd [pwd]
+
+      puts "Running vvp..."
+
+      set vvp_cmd "vvp $name.vvp -lxt2"
+
+      cd $sim_iverilog::output_dir
+
+      #puts [pwd]
+      set results [exec {*}$vvp_cmd]
+
+      # output vvp result
+      puts $results
+
+      cd $cwd
+
+      puts "All done..."
+
+    }
+
+    foreach tb $test_benches {
+      run_sim $tb
+    }
+
+    exit 0
+  }
+
+  # run main
+
+  main
+
+}

Help/counter2/src/verilog/counter.v

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+`timescale 1ns/1ps
+`default_nettype none
+
+// Simple counter_reg with synchronous reset (and no load)
+// 
+
+module counter #(
+    parameter WIDTH = 8,
+    parameter INITIAL_VALUE = 8'h0f
+) (
+    input wire clk,     // global clock
+    input wire reset,   // synchronous reset signal
+    input wire en,      // enable signal
+    output reg strobe   // output strobe
+);
+
+initial strobe = 0;
+
+reg[WIDTH-1:0] counter_reg = INITIAL_VALUE;
+
+always @(posedge clk) begin
+    if (reset) begin
+        counter_reg <= INITIAL_VALUE;
+    end 
+    else if (en) begin
+        strobe <= 0;
+        if (counter_reg == 0) 
+            counter_reg <= INITIAL_VALUE;
+        else begin
+           if (counter_reg == 1) 
+               strobe <= 1;
+           counter_reg <= counter_reg - 1;
+        end
+    end
+
+end
+
+`ifdef FORMAL
+
+reg f_past_valid = 0;
+
+always @* f_past_valid = !$initstate;
+
+always @* begin
+    assume (counter_reg <= INITIAL_VALUE);
+end
+
+always @(posedge clk) begin
+    // if ($initstate) begin
+    //     assume(counter_reg==INITIAL_VALUE);
+    // end
+//    if (!$initstate && $past(en)==1 && !$past(reset)) begin
+    if (f_past_valid && $past(en)==1 && !$past(reset)) begin
+        if (counter_reg < INITIAL_VALUE) 
+            assert (counter_reg == $past(counter_reg) - 1);
+        else begin
+            assert(counter_reg == INITIAL_VALUE && $past(counter_reg)==0);
+        end
+    end
+end
+
+`endif
+
+
+`ifdef VERIFIC
+//internal_check: assert property (@(posedge clk)(counter_reg==11)|=>(counter_reg==10));
+//assert property (@(posedge clk)(counter_reg==11 && en && !reset)|=>(counter_reg==10));
+`endif
+
+    
+endmodule

Help/counter2/verification/counter1.sby

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+[tasks]
+bmc
+prove
+cover
+
+[options]
+bmc: mode bmc
+prove: mode prove
+cover: mode cover
+bmc: depth 100
+
+[engines]
+smtbmc
+#smtbmc z3
+#abc bmc3
+
+
+
+[script]
+read -verific 
+read -sv counter.v
+read -formal counter_formal.sv
+prep -top counter
+
+[files]
+../src/verilog/counter.v
+counter_formal.sv

Help/counter2/verification/counter_formal.sv

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+`default_nettype none
+
+module counter_formal (
+    input wire clk,     // global clock
+    input wire reset,   // synchronous reset signal
+    (*anyseq*) input wire en,      // enable signal
+    input wire strobe,   // output strobe
+    input wire [counter.WIDTH-1:0] counter_reg 
+
+);
+
+`ifdef VERIFIC
+internal_check: assert property (@(posedge clk)
+                        disable iff (reset)
+                       en && (counter_reg==11)|=>(counter_reg==10)) ;
+
+decrease_enable_check: assert property (@(posedge clk)
+                            disable iff (reset || !en)
+                            (counter_reg >0 ) |=> (counter_reg == $past(counter_reg) - 1));
+
+roll_enable_check: assert property (@(posedge clk)
+                            disable iff (reset || !en)
+                            (counter_reg == 0 ) |=> (counter_reg == counter.INITIAL_VALUE));
+
+max_value_assert_check: assert property (
+                            @(posedge clk)
+                            (counter_reg <= counter.INITIAL_VALUE)
+);
+
+cover_0: cover property(
+        @(posedge clk)
+        (counter_reg == 0)
+);
+
+cover_2stb: cover property(
+        @(posedge clk)
+        (strobe == 1) |-> ##[+] (strobe == 1)
+);
+
+
+`endif
+
+endmodule
+
+bind counter counter_formal counter_f_inst(.*);
+
+
+//testing: assert property (@(posedge clk)(counter_reg==111)|=>(counter_reg==10));