Function elements_tx_overhead

bitcoin/tx.h:240–262

Attempt to compute the elements overhead given a base bitcoin size. * * The overhead consists of 2 empty proofs for the transaction, 6 bytes of * proofs per input and 35 bytes per output. In addition the explicit fee * output will add 9 bytes and the per output overhead as well. */

 * output will add 9 bytes and the per output overhead as well.
 */
static inline size_t elements_tx_overhead(const struct chainparams *chainparams,
					  size_t incount, size_t outcount)
{
	size_t overhead;

	if (!chainparams->is_elements)
		return 0;

	/* Each transaction has surjection and rangeproof (both empty
	 * for us as long as we use unblinded L-BTC transactions). */
	overhead = 2 * 4;
	/* For elements we also need to add the fee output and the
	 * overhead for rangeproofs into the mix. */
	overhead += (8 + 1) * 4; /* Bitcoin style output */

	/* All outputs have a bit of elements overhead (incl fee) */
	overhead += (32 + 1 + 1 + 1) * 4 * (outcount + 1); /* Elements added fields */

	/* Inputs have 6 bytes of blank proofs attached. */
	overhead += 6 * incount;

	return overhead;
}

/**
 * Calculate the fees for this transaction