(load "util.scm")
(load "misc/sicp-regsim.scm")

(display "\nex-5.14 - factorial-stack-evaluation\n")

(define factorial-machine (make-machine
  '(n val continue)
  (list (list '= =) (list '- -) (list '* *))
  '(controller
     (assign continue (label fact-done))     ; set up final return address
   fact-loop
     (test (op =) (reg n) (const 1))
     (branch (label base-case))
     ;; Set up for the recursive call by saving n and continue.
     ;; Set up continue so that the computation will continue
     ;; at after-fact when the subroutine returns.
     (save continue)
     (save n)
     (assign n (op -) (reg n) (const 1))
     (assign continue (label after-fact))
     (goto (label fact-loop))
   after-fact
     (restore n)
     (restore continue)
     (assign val (op *) (reg n) (reg val))   ; val now contains n(n - 1)!
     (goto (reg continue))                   ; return to caller
   base-case
     (assign val (const 1))                  ; base case: 1! = 1
     (goto (reg continue))                   ; return to caller
   fact-done)))

(define (run-machine-for n)
  (display "factorial ") (display n)
  ((factorial-machine 'stack) 'initialize)
  (set-register-contents! factorial-machine 'n n)
  (start factorial-machine)
  ((factorial-machine 'stack) 'print-statistics)
  (newline))

(map run-machine-for '(10))

; For each recursion there are two pushes and there are (n - 1) recursions.
; total-pushes(n) = (n - 1) * 2
; max-depth: (n - 1) * 2

(display "\nex-5.15 - instruction-count\n")

(set-register-contents! factorial-machine 'n 1)
(factorial-machine 'reset-instruction-acount)
(start factorial-machine)
(assert (factorial-machine 'instruction-count) 5)

(display "\nex-5.16 - instruction-tracing\n")

(display "[ok]\n")

(display "\nex-5.17 - instruction-tracing-labels\n")

(factorial-machine 'trace-on)
(start factorial-machine)
(factorial-machine 'trace-off)
(start factorial-machine)

(display "\nex-5.18 - register-tracing\n")

((factorial-machine 'trace-on-reg) 'val)
(set-register-contents! factorial-machine 'n 5)
(start factorial-machine)
(assert (get-register-contents factorial-machine 'val) 120)

((factorial-machine 'trace-off-reg) 'val)
(set-register-contents! factorial-machine 'n 5)
(start factorial-machine)

(display "\nex-5.19 - breakpoint\n")

(define (set-breakpoint machine label n)
  ((machine 'set-breakpoint) label n))

(define (cancel-breakpoint machine label n)
  ((machine 'cancel-breakpoint) label n))

(define (proceed machine)
  (machine 'proceed))

(set-register-contents! factorial-machine 'n 6)
(set-register-contents! factorial-machine 'val 0)

(set-breakpoint factorial-machine 'fact-loop 1)
(start factorial-machine)

(assert (get-register-contents factorial-machine 'n) 6)
(proceed factorial-machine)
(assert (get-register-contents factorial-machine 'n) 5)
(proceed factorial-machine)
(cancel-breakpoint factorial-machine 'fact-loop 1)
(assert (get-register-contents factorial-machine 'n) 4)
(proceed factorial-machine)
(assert (get-register-contents factorial-machine 'val) 720)