OPENSSL_store_u32_le
out = OPENSSL_store_u32_le(out, (uint32_t)a2);
out = OPENSSL_store_u32_le(out, z0);
out = OPENSSL_store_u32_le(out, z1);
out = OPENSSL_store_u32_le(out, z0);
out = OPENSSL_store_u32_le(out, z1);
restout = OPENSSL_store_u32_le(out, u32);