atmel_aes_padlen
padlen = atmel_aes_padlen(ivsize, AES_BLOCK_SIZE);
padlen = atmel_aes_padlen(req->assoclen, AES_BLOCK_SIZE);
size_t padlen = atmel_aes_padlen(len, AES_BLOCK_SIZE);
padlen = atmel_aes_padlen(len, dd->ctx->block_size);