How to calculate module 43 in code 39 in php?

Question

PHP

How to calculate the checksum in barcode 39 modulo 43, maybe someone has come across or already wrote something like this.
I tried something like this, but dug deeper, it turned out that this is done differently.

print "<a href=v.php?ix=$ix>$ix</a><br>";
print ord('0');
print ord('1');
print ord('2');
print ord('3');
print ord('-');
print "<br>|||<br>".(ord('1')+ord('2')+ord('3')); 
print "<br>";
print ((ord('1')+ord('2')+ord('3')) % 43);

In the latter, I tried to calculate the checksum 1+2+3 modulo 43

Answer 1

https://github.com/picqer/php-barcode-generator/bl...