Thread: Mutual Exclusion

Hello,

I'm trying to understand algorithm to this mutual exclusion problem/example:

Code:

repeat
(while turn != 0);
// critical section
turn = 1;
// non-critical section
until false;

repeat
(while turn != 1);
// critical section
turn = 0;
// non-critical section
until false;

Why is there a ; after the while statement as if its doing nothing? Does the statement after ; still get executed?

It seems a bit backwards to me. Every example of this solution I see implemented this way.

Why dont they write

Code:

(while turn == 1){
// critical section
}

(while turn == 0){
// critical section
}

This seems to be straight forward. Am I missing something here?

makes sense!