I also fixed the code in order to be able to run it with the data you showed (no commas, no root node) and without creating any files. Adapt to your desires as needed.

#!/usr/bin/perl
use warnings;
use strict;

use XML::Writer;

my @array = split /\n/, << '__CSV__';
name    subname        start size
CAL_M    reserved        0    13
CAL_M    o_check_out    13    7
CAL_M    o_ttr_first    20    4
CAL_M    o_cal_check_1  24    4
PSQN_0    reserved       0    8
PSQN_0    check_final    8    10
PSQN_0    o_check       18    10
__CSV__

my $writer = 'XML::Writer'->new( DATA_MODE   => 1,
                                 DATA_INDENT => 2);

$writer->startTag('root');

my $prev_name = q();
for my $item(@array) {
    chomp $item;
    if (my ($name, $sname, $start, $size) = $item =~/(\w+)\s+(\w+)\s+(
+\d+)\s+(\d+)/) {

        if ($prev_name ne $name) {
            if ($prev_name) {
                $writer->endTag('structure');
            }
            $writer->startTag('structure', name => $name);
        }
        $writer->startTag('value', type  => $size,
                                   name  => $sname,
                                   start => $start,
                         );
        $writer->endTag('value');
        $prev_name = $name;
    }
}
$writer->endTag($_) for qw( structure root );
$writer->end;
[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]