ipc:call   scheme

(define ipc:call
  (lambda (process . args)
    (let* ((callback-proc (ipc:get-process-name))
           (func (if (string? (car args))
                     (begin (set! callback-proc (car args))
                            (set! args (cdr args))
                            (car args))
                     (car args))))
      (let loop ((i *ipc:active-label-cnt*))
        (if (not (null? (vector-ref *ipc:active-labels* i)))
            (loop (modulo (+ i 1) *ipc:active-label-buffer-size*))
            (set! *ipc:active-label-cnt* i)))
      (apply ipc:call-async process 'ipc:sync-receive callback-proc
             *ipc:active-label-cnt* func (cdr args))
      (let ((return-val (call/cc (lambda (k)
                                   (vector-set! *ipc:active-labels* *ipc:active-label-cnt* k)
                                   (*sys:toplevel-continuation* 0)))))
        return-val))))