Contents
- Introduction
- Operation
- Syntax, Keywords
- Command Line options
- Example of input file
- Output of vpp.pl
- Complete script: vpp.pl
Introduction
This is a generic Preprocessor / Macro Processor / Template Processor.
Syntax is different from m4, C preprocessor, Verilog preprocessor.
Since this is a generic text preprocessor, can be used for C, Verilog …
vpp.pl includes documentation of Syntax of input file. Jump to last section for the script.
Why to have another preprocessor for SystemVerilog?
SV is a verbose language. This preprocessor can be used to create template for reuse.
Vpp.pl has more features like for loop, can use perl data types, etc.
For example, UVM testbench skeleton can be made as a template; Use vpp.pl to generate files for agent, driver, monitor, … with uniform naming convention.
Operation
vpp.pl converts input files into perl code. Vpp.pl -p will show generated perl code.
The generated perl code is written as input to perl.
If there are no syntax errors, output is printed. If -o file option is used,
output is written to file instead of stdout.
If there are any syntax errors, error message may be about {, }, (, ), bad words, …,
Exact error in input file can’t be shown. Only location of line, file will be printed.
Syntax, Keywords
Syntax All Keywords Must start at begin of line and end with newline char
Leading spaces will be removed.
Exceptions: $get, $esc, macro calls – $user_defined_macro(…)
Keywords Meaning and Usage
$dnl Delete till newline character. Can be used to write comments
Example: This a line^ $dnl Read all comments. Leading spaces removed
This line will get joined to previous line, immediately after ‘^’
$macro Start of macro definition. Example:
$macro name $dnl Use ‘name’ for definition, Use $name for macro call
arg1 is $get($_[0])
arg2 is $get($_[1])
$end
Macro call: $name(‘arg1′,’arg2’)
$for Example:
$for my $i (1..10)
Iterator is $get($i)
$end
$set Perl Statement that ends with a ‘;’
Example:
$set $x = 5 $dnl Omit ending ‘;’
Value of $x is $get($x)
$begin Use this for perl statements that have ‘{‘
Example:
$begin if($_[0])
$begin while(1)
infinite loop
$end
$end
$begin elsif($_[1])
$begin if($_[2])
true part
$end
$begin else
false part
$end
$end
$end $macro, $for, $begin must end with matching $end
$esc Used to escape characters: ‘$’, ‘(‘, ‘)’
Example:
Use $name(‘$esc(left paran’) in place of $name(‘(left paran’)
Escape keywords: $esc$macro becomes $macro
$get Used to insert value of variables in plain text. See above examples
Can’t be used in lines with $macro, $for, $begin, $set, $end
Example: $get(‘string’) For ‘(‘, ‘)’ within $get, $esc must be used
Same rules of $get apply for user-defined-macro calls
Command line options
USAGE ./vpp.pl files [-o file] [-p] [-s] [-h]
-o Write/Over-Write to file
-p Show Generated Perl Code
-s Show Syntax for input file
-h Show Command line options
Example of input file
******* input.v begins after this line *******
1 abcdefghijklmnopqrstuvwxyz
$macro func
2 ab$get($_[0])cdefg$get (“$esc)”)hijklmnopqrstuvwxyz
$end
3 abcdefghi<<$esc$display>>jklmnopqrstuvwxyz
4 abcdefghijklmnopqrstuvwxyz
5 abcdefg<<$esc($esc)>>hijklmnopqrstuvwxyz
6 abcdefghijklmnopqrstuvwxyz
7 abcdefgh$esc$$$ijklmnopqrs$dnltuvwxyz
8 abcdefghijklmnopqrstuvwxy$esc$escz
9 abcdefghijklmnopqrstuvwxyz
$func(‘FIRST_ARGUMENT’)
$for(1..10) $dnl
$set $x = “argument”
$get($x) is $get($_)
$end
Printing all keyboard characters
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W Z Y Z
1 2 3 4 5 6 7 8 9 0
! @ # $ % ^ & * ( )
` ~ – _ = +
[ { ] } \ |
; : ‘ ”
, < . > / ?
Output of vpp.pl
1 abcdefghijklmnopqrstuvwxyz
3 abcdefghi<<$display>>jklmnopqrstuvwxyz
4 abcdefghijklmnopqrstuvwxyz
5 abcdefg<<()>>hijklmnopqrstuvwxyz
6 abcdefghijklmnopqrstuvwxyz
7 abcdefgh$$$ijklmnopqrs8 abcdefghijklmnopqrstuvwxy$escz
9 abcdefghijklmnopqrstuvwxyz
2 abFIRST_ARGUMENTcdefg)hijklmnopqrstuvwxyz
argument is 1
argument is 2
argument is 3
argument is 4
argument is 5
argument is 6
argument is 7
argument is 8
argument is 9
argument is 10
Printing all keyboard characters
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W Z Y Z
1 2 3 4 5 6 7 8 9 0
! @ # $ % ^ & * ( )
` ~ – _ = +
[ { ] } \ |
; : ‘ “
, < . > / ?
Complete Script: vpp.pl
******* vpp.pl begins after this line *******
#!/usr/bin/perl
# Author : A.G.Raja
# Description : m4 < This Preprocessor <= perl
############## PART1 : Parse Arguments #########################
my $outf = “STDOUT”; my $args = “”; my @infiles; my $genpl=0; my @cmd_out;
sub help { print STDERR “\n$_[0]\n\nUSAGE\t$0 files [-o file] [-p] [-s] [-h]\n\n”;
print STDERR “\t-o\tWrite/Over-Write to file\n”;
print STDERR “\t-p\tShow Generated Perl Code\n”;
print STDERR “\t-s\tShow Syntax for input file\n”;
print STDERR “\t-h\tShow Command line options\n”;
exit; }
sub parse_arguments {
for(my $in=0;$in<=$#ARGV;$in++) {
if($ARGV[$in] =~ /^\-o/) { $in++; $outf=$ARGV[$in]; }
elsif($ARGV[$in] =~ /^\-h/) { &help(“$0 converts input->perl_code->output”); }
elsif($ARGV[$in] =~ /^\-s/) { while(<DATA>) {print;} &help(“Command line options”); }
elsif($ARGV[$in] =~ /^\-p/) { $genpl=1; }
elsif($ARGV[$in] =~ /^\-/) { &help(“ERROR\tInvalid option ‘$ARGV[$in]’\n”); }
else { $args .= “$ARGV[$in] “; push(@infiles,$ARGV[$in]); } }
if($args !~ /\w+/) { &help(“ERROR\tNo input files specified\n”); }
if($outf =~ />\s*$/) { &help(“ERROR\tNo output file specified\n”); } }
############## PART2 : Text2Perl Conversion ####################
my $tt = “TEXT”; my $ee = “ESCAPE”; my $bt=”BEGIN$tt”; my $et=”END$tt”;
my $esn = $ee.”N”; my $esl = $ee.”L”; my $esr = $ee.”R”; my $esd = $ee.”D”;
my %hash; $hash{“get”}=”print”;
sub define_macro { my $n = shift; $n=~ s/\s//g; $hash{$n}=$n; }
sub macro_call {
my $out=””; my $func=””; my @l;
@l = split(/(\$\w+\s*\(|\))/,shift);
for(my $i=0;$i<=$#l;$i++) {
if($l[$i]=~/\$(\w+)/) {
$func=$hash{$1};
if($func ne “”) {
$out .= “$et $func(” ; $i++;
$out .= $l[$i] ; $i++;
$out .= “$l[$i]; $bt”; next; } }
$out .= $l[$i]; }
return $out; }
sub print_text {
my $in = shift;
if($in eq “”) { return “”; }
$in =~ s/\\/\\\\/g;
$in =~ s/\’/\\\’/g;
return “print ‘$in’;”; }
sub perl_code {
my ($prefix,$middle,$suffix,) = @_; my $ret;
$ret = “$et $prefix”;
if($middle =~ /(.*)$et($esn$bt)/) {
$ret .= “$1 $suffix$2”;
if($prefix eq “sub”) { &define_macro($1); } }
else {
if($prefix eq “sub”) { &define_macro($middle); }
$ret .= “$middle $suffix\n$bt”; }
return $ret; }
sub parse {
my $l = shift;
#$l=~s/\r//; # Uncomment This Line to run on Windows OS
$l=~s/[\$]esc\$/$esd/g;
$l=~s/[\$]esc\(/$esl/g;
$l=~s/[\$]esc\)/$esr/g;
$l=~s/[\$]dnl.*\n/$et$esn$bt/;
if($l=~/^\s*[\$]macro(.*)/) { $l = &perl_code(“sub”,$1,”{“); }
elsif($l=~/^\s*[\$]for(.*)/) { $l = &perl_code(“for”,$1,”{“); }
elsif($l=~/^\s*[\$]begin(.*)/) { $l = &perl_code(“” ,$1,”{“); }
elsif($l=~/^\s*[\$]set(.*)/) { $l = &perl_code(“” ,$1,”;”); }
elsif($l=~/^\s*[\$]end.*/) { $l = &perl_code(“}” ,””,”” ); }
else { $l = ¯o_call($l); }
$l=~s/$esl/(/g;
$l=~s/$esr/)/g;
$l=~s/$esd/\$/g;
$l=~s/$esn/\n/g;
return $l; }
sub text2perl {
my $Text = shift;
my $out=””; my $pl=0; my @l;
@l = split(/($bt|$et|\n)/,$$Text);
for(@l) {
if($_ eq “$bt”) { $pl=0; }
elsif($_ eq “$et”) { $pl=1; }
elsif($_ eq “\n”) { $out .= $pl ? “\n” : “print \”\\n\”;\n”; }
else { $out .= $pl ? $_ : &print_text($_); } }
print “$out print \”Text2Perl Completed\”;”; }
############## PART3 : VPP – Generate Output ###################
sub vpp {
@cmd_out = `$0 -p $args | perl 2>&1`;
if($cmd_out[$#cmd_out]=~/Text2Perl Completed$/) {
$cmd_out[$#cmd_out]=~s/Text2Perl Completed$//;
if($outf eq “STDOUT”) { for(@cmd_out) {print;} exit; }
open(FILE,”>$outf”) or &help(“Can’t Write file ‘$outf'”);
for(@cmd_out) {print FILE;}
close(FILE);
return 1; }
return 0; }
my @b; my @e;
sub file_name {
my $ln = shift; my $act;
for(my $i=0;$i<=$#b;$i++) {
if( ($ln>$b[$i]) && ($ln<=$e[$i]+1) ) {
$act = $ln-$b[$i];
return “$act in ‘$infiles[$i]'”; } }
return “$ln”; }
sub report_errors {
my $line; my $curr=0;
for my $inf (@infiles) {
push(@b,$curr);
open(TEMP,”<$inf”) or last;
$line=0; while(<TEMP>) {$line++;}
close(TEMP);
$curr+=$line;
push(@e,$curr); }
for(@cmd_out) {
if(/\-\s*line\s*(\d+)/) {
$actual = &file_name($1);
s/(\-\s*line\s*)\d+/$1$actual/; }
print $_; } }
############## PART4 : Select Text2Perl / VPP ##################
&parse_arguments();
if(!$genpl) {
if(!&vpp()) { &report_errors(); }
exit; }
my $text=””;
for my $inf (@infiles) {
open(TEMP,”<$inf”) or last;
while(<TEMP>) { $text.=&parse($_); }
close(TEMP); }
&text2perl(\$text);
__DATA__
Syntax, Keywords, Usage Examples
Syntax All Keywords Must start at begin of line and end with newline char
Leading spaces will be removed.
Exceptions: $get, $esc, macro calls – $user_defined_macro(…)
Keywords Meaning and Usage
$dnl Delete till newline character. Can be used to write comments
Example: This a line^ $dnl Read all comments. Leading spaces removed
This line will get joined to previous line, immediately after ‘^’
$macro Start of macro definition. Example:
$macro name $dnl Use ‘name’ for definition, Use $name for macro call
arg1 is $get($_[0])
arg2 is $get($_[1])
$end
Macro call: $name(‘arg1′,’arg2’)
$for Example:
$for my $i (1..10)
Iterator is $get($i)
$end
$set Perl Statement that ends with a ‘;’
Example:
$set $x = 5 $dnl Omit ending ‘;’
Value of $x is $get($x)
$begin Use this for perl statements that have ‘{‘
Example:
$begin if($_[0])
$begin while(1)
infinite loop
$end
$end
$begin elsif($_[1])
$begin if($_[2])
true part
$end
$begin else
false part
$end
$end
$end $macro, $for, $begin must end with matching $end
$esc Used to escape characters: ‘$’, ‘(‘, ‘)’
Example:
Use $name(‘$esc(left paran’) in place of $name(‘(left paran’)
Escape keywords: $esc$macro becomes $macro
$get Used to insert value of variables in plain text. See above examples
Can’t be used in lines with $macro, $for, $begin, $set, $end
Example: $get(‘string’) For ‘(‘, ‘)’ within $get, $esc must be used
Same rules of $get apply for user-defined-macro calls
Applied Electronics Journal 