Function to generate OCR line on invoices payable via Bankgirot.

generate_bankgirot_ocr.php

<?php

/*
 Author: T. Almroth
 Documentation: https://www.bankgirot.se/globalassets/dokument/anvandarmanualer/bankgiroinbetalningar_anvandarmanual_sv.pdf
 Note: Use font OCR B.
 Example of use:
 echo generate_bankgirot_ocr('123456789', '100.00', '0000-0000');
 */

function modulus10($number) {

  $number = preg_replace('#[^0-9]#', '', $number);

  $digits = str_split(strrev($number));
  $stack = 0;

  foreach ($digits as $key => $value) {
    if ($key % 2 == 0) {
      $value = array_sum(str_split($value * 2));
    }
    $stack += $value;
  }

  $stack %= 10;

  if ($stack != 0) {
    $stack -= 10;
    $stack = abs($stack);
  }

  return strval($stack);
}

function generate_bankgirot_ocr(string $ocr_number, string $amount, string $account) {
  
  return strtr('#.{ocr}.#{amount}.{cents}...{checksum}.>.................{account}#{code}#....', [
    '.' => ' ',
    '{ocr}' => str_pad($ocr_number, 25, ' ', STR_PAD_LEFT),
    '{account}' => str_pad(str_replace('-', '', $account_number), 8, ' ', STR_PAD_LEFT),
    '{amount}' => str_pad($whole = floor($amount), 8, ' ', STR_PAD_LEFT),
    '{cents}' => str_pad(round(($amount - $whole) * 100), 2, '0', STR_PAD_LEFT),
    '{checksum}' => modulus10($amount),
    '{code}' => 41,
  ]);
}