SWAP(variable)
Swap high and low part of a variable.
For 8-bit BYTE, CHAR or SHORTINT variables, it swaps low and high 4-bit nibbles.
For 16-bit INTEGER or WORD variables, it swaps low and high 8-bit.
For 32-bit LONGINT or LONGWORD variables, it swaps low and high 16-bit.
Other types are not supported.