BF_ROUNDS
#if BF_ROUNDS == 20
r ^= p[BF_ROUNDS + 1];
l ^= p[BF_ROUNDS + 1];
#if BF_ROUNDS == 20
#if (BF_ROUNDS != 16) && (BF_ROUNDS != 20)
If you set BF_ROUNDS to some value other than 16 or 20, you will have
for (i = 0; i < BF_ROUNDS + 2; i += 2) {
if (len > ((BF_ROUNDS + 2) * 4))
len = (BF_ROUNDS + 2) * 4;
for (i = 0; i < BF_ROUNDS + 2; i++) {
BF_LONG P[BF_ROUNDS+2];