Given that a machine instruction Swap exists with the following semantics:

procedure Swap (var a, b: Boolean) /* A procedure does not return value upon exit.

Keyword var used in the definition of parameters

indicates that they are passed by reference. */

var temp : Boolean; /* temp is a local variable */

begin

temp := a;

a := b;

b := temp;

end;

Show how you can use such a Swap instruction to implement a spin-lock mechanism for mutual exclusion. (The spin-lock mechanism in the lecture notes based on a given test-and-set instruction may be a good model for your answer.)