Bitwise endian swap for various types

Question

With the help of various sources, I have written some SwapBytes methods in my binary reader class that swap endian in ushort, uint, an

Answer 1

Instead of conceptually deconstructing to separate bytes and then reassembling them the other way around, you can conceptually swap groups of bytes, like this: (not tested)

public uint SwapBytes(uint x)
{
    // swap adjacent 16-bit blocks
    x = (x >> 16) | (x << 16);
    // swap adjacent 8-bit blocks
    return ((x & 0xFF00FF00) >> 8) | ((x & 0x00FF00FF) << 8);
}

Doesn't help much (or at all) for 32 bits, but for 64 bits it does (not tested)

public ulong SwapBytes(ulong x)
{
    // swap adjacent 32-bit blocks
    x = (x >> 32) | (x << 32);
    // swap adjacent 16-bit blocks
    x = ((x & 0xFFFF0000FFFF0000) >> 16) | ((x & 0x0000FFFF0000FFFF) << 16);
    // swap adjacent 8-bit blocks
    return ((x & 0xFF00FF00FF00FF00) >> 8) | ((x & 0x00FF00FF00FF00FF) << 8);
}

For signed types, just cast to unsigned, do this, then cast back.