Function generate_code 

pub fn generate_code(
    secret_key: &[u8; 32],
    counter: u64,
    alphabet: &Alphabet,
    code_length: usize,
    check_position: CheckPosition,
    damm_table: &DammTable,
) -> String

Generate a single promotional code from a counter value.

Arguments

• secret_key - 32-byte secret key for HMAC
• counter - Counter value (unique per code)
• alphabet - Character set for the code
• code_length - Number of random characters (check digit added separately)
• check_position - Where to place the check digit (index-based)
• damm_table - Damm table for check digit calculation

Returns

Generated code string with length = code_length + 1 (including check digit)

Example

use promocrypt_core::{generate_code, Alphabet, DammTable, CheckPosition};

let secret = [0u8; 32];
let alphabet = Alphabet::default_alphabet();
let damm = DammTable::new(alphabet.len());

let code = generate_code(&secret, 0, &alphabet, 9, CheckPosition::End, &damm);
assert_eq!(code.len(), 10);