Bit shift operations are not portable across all processor architectures, different processors can have different bit-widths. In other words, if you wrote
int a = ~0; int b = a << 1;
This value would be different on a 64 bit machine vs. on a 32 bit machine, or from an x86 based processor to a PIC based processor.
Endian-ness does not need to be taken into account for the bit wise operations themselves, that is, the right shift (
>>) will shift the bits towards the least significant bit and an XOR will perform an exclusive or on the bits. Endian-ness only needs to be taken into account with the data itself, that is, if endian-ness is a concern for your application, it's a concern regardless of bit wise operations.