The ground is Rotating!

[the3rdStorm]

Here’s a Rotation function to recycle bits from the ‘bit bucket’,

unsigned char rol(unsigned char val) {
  int highbit;
  if(val & 0x80) // 0x80 is the high bit only
    highbit = 1;
  else
    highbit = 0;
  // Left shift (bottom bit becomes 0):
  val <<= 1;
  // Rotate the high bit onto the bottom:
  val |= highbit;
  return val;
}

Questions:
1. Why use 0x80(128) to check for the high bit?
2. Can you please explain the use of the Rotation?
3. Is there any other ways to do the Rotation?

Thanks.