Generate IS (Inpay Slip by Postfinance) codeline with PHP

is.php

<?php
  // Check for more info: https://www.postfinance.ch/binp/postfinance/public/dam.Ii-X5NgtAixO8cQPvja46blV6d7cZCyGUscxO15L5S8.spool/content/dam/pf/de/doc/consult/manual/dldata/efin_recdescr_man_en.pdf
  // Thanks to:
  // - https://gist.github.com/gbaudoin/9066c1a3d6ab68351635
  // - https://gist.github.com/christianmeichtry/9348451
  // - http://dnando.github.io/blog/2014/09/23/check-digit-computation-swiss-pay-slips/
  $slipType = "01";
  $amount = 3949.75;
  $referenceNumber = "12 00000 00000 23447 89432 16899";
  $subNumber = "01-162-8";

  function genCodeline($slipType, $amount, $rnumb, $subNumb)
  {
      $isEur = false;
      if ((int) $slipType > 14) {
          $isEur = true;
      } else {
          $amount = .5 * round((float) $amount/.5, 1);
      }

      if (!$isEur && $amount > 99999999.95) {
          throw new Error("Invalid amount");
      } elseif ($isEur && $amount > 99999999.99) {
          throw new Error("Invalid amount");
      }
      $amountLine = sprintf("%010d", $amount * 100);
      $checkSlAmount = recMod10($slipType.$amountLine);

      if(!preg_match("/\d{2}-\d{1,6}-\d{1}/", $subNumb)){
        throw new Error("Invalid subscriber number");
      }

      $subNumb = explode("-", $subNumb);
      $fullSub = $subNumb[0].sprintf("%08d", $subNumb[1]).$subNumb[2];

      $rnumb = preg_replace('/\s+/', '', $rnumb);

      return $slipType.$amountLine.$checkSlAmount.">".$rnumb."+ ".$fullSub.">";
  }

  function recMod10($in)
  {
      $line = [0,9,4,6,8,2,7,1,3,5];
      $carry = 0;
      $chars = str_split($in);
      foreach($chars as $char){
        $carry = $line[($carry+intval($char))% 10];
      }
      return (10-$carry) %10;
  }

  echo genCodeline($slipType, $amount, $referenceNumber, $subNumber);

  ?>