Motivational Quotes

January 20th, 2010
  1. When tough time comes… The tough keep going!
  2. I have not failed. I’ve just found 10,000 ways that won’t work. – Thomas A. Edison

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Multi Dimentional Associative array with modelsim

April 30th, 2009

We are trying to compile ovm on the vcs and and I came across some code which was giving issue with VCS but it works in modelsim. So here is what the code looks like :

typedef int pint;
typedef pint pnewint[string];

module test;
pnewint aa [string];
initial begin
aa["ss"]["ss"] = 1;
$display (”I am here in test %d \n”, aa["ss"]["ss"]);
end
endmodule

Output :

=====

VSIM 1> run
run
# I am here in test           1
#

After that I tried a direct deceleration test like :

module test;
int aa [string] [string];
initial begin
aa["ss"]["ss"] = 1;
$display (”I am here in test %d \n”, aa["ss"]["ss"]);
end
endmodule

Output :

=====

VSIM 1> run
run
# I am here in test           1
#

So basically the above statements mean that modelsim allow multi dimentional associative array creation. Now the question is  does LRM allows it.  I guess it does not :( .

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Posted in System Verilog | No Comments »

Ignoring files in svn stat

April 29th, 2009

Sometimes when you have your object files inside your source directory and you try to do “svn stat”, It gives too verbose information about the gernerated object files with ? sign. You can mark them as ignore in svn using propedit so that next time when you do “svn stat” they wont be compared.

You can do it using :

svn propedit svn:ignore objects/

and in the log file enter ‘*’.  With the above command svn will ignore all files inside objects for comparison in svn stat.

Thanks,

Puneet

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Changing OVM verbosity from command line

March 31st, 2009

Methodologies helps in building the verification environment. But they sucks also.  A small mistake takes lots of time to figure out. If you are using OVM and stuck with debugging some wired error, you can increase the OVM verbosity level from the command line to see what exactly is happening inside the OVM macro’s and classes.  Pass the below switch with the command line options.

+OVM_VERBOSITY=600

or something like :

vsim +OVM_TESTNAME=mem_bitwalk_test +OVM_VERBOSITY=600 -do run.do -c mem_tb_top

Tags:
Posted in System Verilog | No Comments »

Mixed verilog and vhdl compilation with VCS

March 30th, 2009

Here I will explain how you can compile and simulate vhdl and verlog based design using the VCS. lets take a small example of counter. The dut will be written in vhdl and the testbench we will write in verilog. Then we will instantiate vhdl counter into our verilog testbench and then compile and simulate it.

Here is the code for dut and testbench.

VHDL DUT :
==========

library ieee ;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity counter is
port(  clk:  in std_logic;
  reset:  in std_logic;
  enable:  in std_logic;
  count:  out std_logic_vector(3 downto 0)
);
end counter;

architecture behav of counter is
  signal pre_count: std_logic_vector(3 downto 0);
  begin
    process(clk, enable, reset)
    begin
      if reset = '1' then
        pre_count <= "0000";
      elsif (clk='1' and clk'event) then
        if enable = '1' then
          pre_count <= pre_count + "1";
        end if;
      end if;
    end process;
    count <= pre_count;
end behav;

Verilog Testbench
=================

module counterTb;
    reg clk;
    reg reset;
    reg enable;
    wire [3:0] count;

    initial
    begin
        $monitor ($time, " Count = %d", count);
        clk=0;
        reset = 1;
        enable = 0;
        #5
        reset = 0;
        enable = 1;
    end

    initial
        forever
            #5 clk = ~clk;

    initial
        #1000 $finish;

   // initialize vhdl counter module
   counter (.clk(clk),.reset(reset),.enable(enable), .count(count));

endmodule

Steps to compile :
* Create directory for the compiled libraries (mkdir compile)

* Setup “synopsys_sim.setup” file and map libraries in it

  • Create file synoosys_sim.setup
  • Add line : counter_lib : ./compile/

* Compile the libraries

  • vhdlan -work counter_lib counter.vhdl
  • vlogan +v2k +incdir+./ -work counter_lib countertb.v

* Elobrate the design and generate executable

  • vcs counter_lib.counterTb

* Simulate it.

  • ./simv

You can create a makefile also to design and elobrate the design. Something like

all : compile sim

counter_lib : counter.vhdl
    vhdlan -work counter_lib counter.vhdl

countertb_lib : countertb.v
    vlogan +v2k +incdir+./  -work counter_lib countertb.v

compile : countertb_lib counter_lib

sim :
    vcs counter_lib.counterTb

Now you just need to say “make”. It will compile and elobrate the design.

synopsys_sim.setup file content
===============================

counter_lib : ./compile/
WORK>DEFAULT
DEFAULT: ./compile/
ASSERT_IGNORE_WARNING=TRUE
ASSERT_IGNORE_FAILURE=TRUE
ASSERT_IGNORE_ERROR=TRUE

Tags: , , ,
Posted in Verilog, Vhdl | No Comments »

Usefull vimdiff commands to view diff and merge

October 15th, 2008

Diffing the files and merging them is one of the very common task we do everyday. Following are few very useful commands to view the diff using vim and merge them using the vimdiff commands instead of copying and pasting from one file to another.

To diff two files using vim :

vimdiff file1 file2
or
vim -d file1 file2

Ofcourse you can use gvim also but I don’t prefer using GVIM.

gvimdiff file1 file2

Commands :

[c : Jump to previous diff
]c : Jump to the next diff

do or :diffget : Diff obtain (get the changes to the current buffer/file from the other buffer)
dp or :diffput : Diff Put (Put the changes from the current buffer/file to the other buffer)

As this being one of very command task I do, I have mapped them to single keys for the easy access.

nmap <F7> [czz
nmap <F8> ]czz
nmap <F2> do
nmap <F3> dp

The zz in the end of the command [c will center at the point of the diff so that we can view the diff clearly.

~Enjoy Vim

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Changing the seed for a class and generting different patterent for randc

September 9th, 2008

Here is the example. How you can change the seed for a class and generate different pattern with randc.
If you comment the line “obj.srandom(seed)” it will generate the same pattern again after the cycle.
Try compiling it again with commenting above line.

class randctest;
randc bit [1:0] randbit;
task print;
$display(”Rand C = %d”, randbit);
endtask
endclass

program main;

randctest obj;

initial begin
obj = new();
for (int i=0; i<12; i++) begin
if (i % 4 == 0) begin
obj.srandom(236+i);
$display(”==============”);
end
if (obj.randomize()) begin
obj.print();
end
else begin
$display(”Randomization failed \n”);
end
end
end
endprogram : main

Output :
==============
Rand C = 0
Rand C = 1
Rand C = 2
Rand C = 3
==============
Rand C = 2
Rand C = 1
Rand C = 3
Rand C = 0
==============
Rand C = 1
Rand C = 0
Rand C = 2
Rand C = 3

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Smart Person Vs Wise Person

September 5th, 2008

A good thought :

The difference between a smart person and a wise person is that a wise
person knows how not to get into situations that a smart person knows
how to get out of.

Reference Page :

http://simeons.wordpress.com/2008/09/04/smart-entrepreneurs-vs-wise-entrepreneurs/

Page has few more thoughts out of which the last one i don’t agree :

  • Be different, not best
  • Do less, not more
  • Go around a wall, not through it
  • It is better to figure out how not to have to solve a problem as opposed to having to solve the problem.

Posted in Randsom Stuff | No Comments »

Sourcing a Shell script into perl

August 21st, 2008

A lot of times we require to source the shell variables or shell script into the perl environment. One way to do this is you add very variable into the perl script something like :

$ENV{”SOME_VAR”} = “SOME_VAL”;

The other best way to do this task is parse the shell file and source all the environment variables in to perl script environment. This way we don’t need to modify your perl script every time the shell script is modified. :)

my ($envar, $enval);
open IN, “. ./3rdParty.env; env |”
or die “Could not run shell: $!\n”;
while ( <IN> ) {
print $_;
chomp;
($envar,$enval) = split /=/,$_,2;
$ENV{$envar} = $enval;
}
close IN;

This is very useful if the shell script is changed very frequently by the users.

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Ways to add library path in perl

August 21st, 2008

Run a perl script using libraries in nonstandard locations.
======================================

Use perl -V to see the include paths @INC array
I will be something like :
/usr/lib/perl5/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/5.8.0
/usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.0
/usr/lib/perl5/site_perl
/usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.0
/usr/lib/perl5/vendor_perl


1. Using the module lib
===============
The standard module lib can be used to specify an explicit path to include. It must be stated at the
top of the script:
#!/usr/bin/perl
#
use lib “/opt/special/plib”;
use strict;
use warnings;

2. Using the switch -I at the command line
============================

The switch I can be used to specify additional library locations when invoking the interpreter.
perl -I /opt/special/plib script.pl

3. Using the switch -I in the first line of the script
=================================
The same I switch can be added to the interpreter specification.
#!/usr/bin/perl -I /opt/special/plib
#
use strict;
use warnings;
..

This works when invoking the script via the shell (which will run the interpreter with full
options and arguments as specified in the first line) and also when invoking the interpreter
directly: It apparently scans the first line for options.

4. Manipulating @INC directly
====================
The array @INC can be manipulated directly using array operations :

#!/usr/bin/perl
#
BEGIN {
unshift(@INC, “/opt/special/plib”);
}
use strict;
use warnings;

5. Using the environment variable PERL5LIB
==============================
The environment variable PERL5LIB can be used to specify additional include directories whe
running a perl script.
> export PERL5LIB=/opt/special/plib

6. Changing @INC at compile time
=======================
When running Configure to compile the perl interpreter itself, there are several possibilities to add
additional library path elements:
· Using the variable vendorprefix
· Using the variable otherlibdirs
Both must be specified when calling Configure as a define, eg
> sh Configure -Dotherlibdirs=/opt/special/plib
The variable otherlibdirs is preferred, as it can hold mutliple values separated by a colon just like
the familiar PATH environment variable.
Details about compiling perl can be found on the CPAN network :
http://search.cpan.org/~nwclark/perl5.8.3/INSTALL.

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