mcrypt_enc_get_algorithms_name

<?php
    $td = mcrypt_module_open (MCRYPT_CAST_256, '', MCRYPT_MODE_CFB, '');
    echo mcrypt_enc_get_algorithms_name($td). "\n";
  
    $td = mcrypt_module_open ('cast-256', '', MCRYPT_MODE_CFB, '');
    echo mcrypt_enc_get_algorithms_name($td). "\n";
?>

Prints:
CAST-256
CAST-256