From SICP:Exercise 3.47.  A semaphore (of size  n) is a generalization of a mutex.  Like a mutex, a semaphore supports  acquire and release operations, but it  is more general in that up to n  processes can acquire it concurrently.  Additional processes that attempt to  acquire the semaphore must wait for  release operations. Give  implementations of semaphoresb. in terms of atomic test-and-set!  operations.(define (make-semaphore max)  (let ((count 0)        (cell (list false)))    (define (increment)      (set! count (+ count 1)))    (define (decrement)      (set! count (- count 1)))    (define (has-room?) (> max count))    (define (the-semaphore m)      (cond ((eq? m 'acquire)             (if (has-room?)                 (increment)                 (if (test-and-set! cell) (the-semaphore 'acquire))))            ((eq? m 'release)             (decrement)             (if (has-room?) (clear! cell)))))    the-semaphore))(define (clear! cell)  (set-car! cell false))(define (test-and-set! cell)  (if (car cell)      true      (begin (set-car! cell true)             false)))Do you think that this solution is sufficient?  Can it be improved?
Write a definition of a semaphore in terms of test-and-set! operations
lisp;scheme;sicp