local $/;
open(IN,qq|adatafile.txt|) or die $!;
my $infile = <IN>;
my $begin_stuff;
my $end_stuff;
my %mid_stuff;

close(IN);

if($infile=~m/(.*)\#\s+__START_CONFIG__/s){
    $begin_stuff = $1;
}

if($infile=~m/__START_CONFIG__(.*)\# __END_CONFIG__/s){
    my $tmp = $1;
    while($tmp=~m/([^=\s]+)=([^=]+)\n/g){
        $mid_stuff{$1} = $2;
    }
 }
#if ..oh hell, you get the bloody idea...

print Dumper \%mid_stuff;