#define CTL_BYTE_SWAP_16b_LIT(N) \ ((((N) & 0xFF) << 8) | \ (((N) & 0xFF00) >> 8))
CTL_BYTE_SWAP_16b_LIT reverses the byte order of the two least significant 16 bits of N and returns that value. You can use this macro to initialize a static variable with a byte-swapped constant.