#!/usr/bin/perl -w
use strict;
use CGI qw/:standard /;
my $source = param('source') || "";
if($source ne "") {
my @raw = split /\n/, $source;
my @lines = &lex(@raw);
# symbol table
my %sym_table;
#first run to find data
my $pos = "[##THETA NOT SET##]";
foreach my $line (@lines){
if($line =~ /GK/){
$pos = -1;
}
if($line =~ /\[\=(.*)\]/) {
$sym_table{$1} = $pos;
}
if($pos >= -1){ $pos++ }
}
# now go back and make the switches
print header, "EDSAC code\n";
$pos = "[##theta not set##]";
foreach my $line (@lines) {
if($line =~ /GK/){
$pos = -1;
}
$line =~ s/\s*\[\$here\$\] */$pos/g;
$line =~ s/\s*\[\$(.*)\] */$sym_table{$1}/g;
$line =~ s/\s*\[\=(.*)\] *//g;
print $line;
if($pos >= -1){ $pos++ }
}
print "";
} else {
print header;
print<EDSAC assembler
END_HTML
}
# simple lexer. removes comments and blank lines
sub lex {
my @raw_code = @_;
my @results = ();
foreach my $line (@raw_code){
$line =~ s/\[\#.*\]//g;
if($line =~ /\S/){
# if there's anything that isn't whitespace
# we add it
push @results, $line;
}
}
return @results;
}