#!/usr/bin/env perl -n
#
#   first, read in a pdb file line and unpack
#

if( $_ =~ /^ATOM|^HETATM/){

#  expand to 80+ characters (really hokey version):
chop($_);
$_ .= "                                                                    ";

( $label, $atno, $atname, $alt, $resname, $chainId, $resno, $iCode,
      $x, $y, $z, $occ, $bfact, $element, $charge ) =
    unpack("a6 a5 x a4 a a3 x a a4 a x3 a8 a8 a8 a6 a6 x10 a2 a2",$_);

#
#  do modifications necessary here:
#
if( $chainId eq "H" && $atname =~ /O/){
   $newresno++;
   $resno = $newresno;
} elsif(  $chainId eq "H" && $atname =~ /H/ ){
   $resno = $newresno;
}

#
#  write back out
#
printf 
"%6s%5s %-4s%1s%3s %1s%4s%1s   %8.3f%8.3f%8.3f%6.2f%6.2f          %2s%2s\n",
      $label, $atno,$atname,$alt, $resname,$chainId, $resno, $iCode,
        $x,$y,$z, $occ, $bfact, $element, $charge;

} elsif( $_ =~ /^ANISOU/){
#  expand to 80+ characters (really hokey version):
chop($_);
$_ .= "                                                                    ";

( $label, $atno, $atname, $alt, $resname, $chainId, $resno, $iCode,
    $u11, $u22, $u33, $u12, $u13, $u23, $element, $charge ) =
    unpack("a6 a5 x a4 a a3 x a a4 a x a7 a7 a7 a7 a7 a7 x6 a2 a2",$_);

#
#  do modifications necessary here:
#

#
#  write back out
#
printf 
"%6s%5s %-4s%1s%3s %1s%4s%1s %7s%7s%7s%7s%7s%7s      %2s%2s\n",
      $label, $atno,$atname,$alt, $resname,$chainId, $resno, $iCode,
        $u11, $u22, $u33, $u12, $u13, $u23, $element, $charge;

} else {
   print;
}