use strict;
use warnings;

use 5.010;

my $text  = q{xxxAAsgdhsdgABudhwuACedAGuwydADwieuhwiudAEudwdfuw};
my $tag   = shift || q{AA};
my $limit = q{ZZ};

my @records  = ();
my $prevPosn = index $text, $tag, 0;
die  qq{ERROR: First record '$tag' not found in text\n}
   if $prevPosn == -1;
warn qq{WARNING: First record '$tag' not at start of text\n}
   unless $prevPosn == 0;

while ( ( my $posn = index $text, ++ $tag, $prevPosn + 2 ) != -1 )
{
    push @records, substr $text, $prevPosn, $posn - $prevPosn;
    $prevPosn = $posn;
    last if $tag eq q{ZZ};
}
push @records, substr $text, $prevPosn;

say qq{>$_<} for @records;