;;-*-Lisp-*-
(in-package goal)

;; name: timer.gc
;; name in dgo: timer
;; dgos: GAME, ENGINE


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Timer (EE timers)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun timer-reset ((timer timer-bank))
  "Reset a timer's counter to zero"

  (#when PC_PORT
    ;; just store the current offset.
    (if (= timer TIMER1_BANK)
        (set! *timer-reset-value* (get-bus-clock/256))
        (format 0 "Unknown timer #x~X in timer-reset~%")
        )
    (return (the uint 0))
    )
  (.sync.l)
  (set! (-> timer count) 0)
  (.sync.l)
  )

(defun timer-count ((timer timer-bank))
  "Return a timer's counter value"

  (#when PC_PORT
    (when (= timer TIMER1_BANK)
      (return (- (get-bus-clock/256) *timer-reset-value*))
      )
    (format 0 "Unknown timer #x~X requested.~%" timer)
    )

  (.sync.l)
  (let ((count (-> timer count)))
    (.sync.l)
    count
    )
  )

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Interrupt Control
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; cop0 status register "interrupt enable" flag
;; if cop0 status is needed anywhere else, move this elsewhere
(defconstant COP0_STATUS_IE (the-as uint #x1))

(defun disable-irq ()
  "Disable all interrupts. Has no effect on PC Port"
  (rlet ((status :class gpr :type uint))
    (let ((status-mask (lognot COP0_STATUS_IE)))
      (.mfc0 status Status)
      (logand! status status-mask) ;; should status-mask be replaced directly?
      (.mtc0 Status status)
      (.sync.p)
      )
    )
  )

(defun enable-irq ()
  "Enable all interrupts. Has no effect on PC Port."
  (rlet ((status :class gpr :type uint))
    (.mfc0 status Status)
    (logior! status COP0_STATUS_IE)
    (.mtc0 Status status)
    (.sync.p)
    )
  )


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Stopwatch (CPU clock cycle counting)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun stopwatch-init ((obj stopwatch))
  "Init a stopwatch"
  (set! (-> obj begin-level) 0)
  (set! (-> obj prev-time-elapsed) 0)
  )


(defun stopwatch-reset ((obj stopwatch))
  "Restart a stopwatch's times"
  (set! (-> obj prev-time-elapsed) 0)
  (when (> (-> obj begin-level) 0)
    (let ((count 0))
      (.mfc0 count Count)
      (#when PC_PORT
        (set! count (the int (get-cpu-clock)))
        )
      (set! (-> obj start-time) count)
      )
    )
  )

(defun stopwatch-start ((obj stopwatch))
  "Start a stopwatch from scratch"
  (when (zero? (-> obj begin-level))
    (set! (-> obj begin-level) 1)
    (let ((count 0))
      (.mfc0 count Count)
      (#when PC_PORT
        (set! count (the int (get-cpu-clock)))
        )
      (set! (-> obj start-time) count)
      )
    )
  )

(defun stopwatch-stop ((obj stopwatch))
  "Fully stop a stopwatch and save its elapsed time"
  (when (> (-> obj begin-level) 0)
    (set! (-> obj begin-level) 0)
    (let ((count 0))
      (let ((count 0))
        (.mfc0 count Count) ;; wrong register? a typo in a rlet? who knows.
        (#when PC_PORT
          (set! count (the int (get-cpu-clock)))
          )
        (+! (-> obj prev-time-elapsed) (- count (-> obj start-time)))
        )
      )
    )
  (none)
  )

(defun stopwatch-begin ((obj stopwatch))
  "Begin a stopwatch level, and starts it if it hasn't yet"
  (when (zero? (-> obj begin-level))
    (let ((count 0))
      (.mfc0 count Count)
      (#when PC_PORT
        (set! count (the int (get-cpu-clock)))
        )
      (set! (-> obj start-time) count)
      )
    )
  (+! (-> obj begin-level) 1)
  )

(defun stopwatch-end ((obj stopwatch))
  "End a stopwatch level. Stops the stopwatch if it's back to level zero.
   There is no guard against ending a stopwatch too many times, and a negative level
   will cause errors!"
  (+! (-> obj begin-level) -1)
  (when (zero? (-> obj begin-level))
    (set! (-> obj begin-level) 0)
    (let ((count 0))
      (.mfc0 count Count)
      (#when PC_PORT
        (set! count (the int (get-cpu-clock)))
        )

      (+! (-> obj prev-time-elapsed) (- count (-> obj start-time)))
      )
    )
  (none)
  )

(defun stopwatch-elapsed-ticks ((obj stopwatch))
  "Returns the elapsed time so far (in clock cycles) of a stopwatch"
  (let ((elapsed (-> obj prev-time-elapsed)))
    (when (> (-> obj begin-level) 0)
      (let ((count 0))
        (.mfc0 count Count)
        (#when PC_PORT
          (set! count (the int (get-cpu-clock)))
          )

        (+! elapsed (- count (-> obj start-time)))
        (set! count elapsed) ;; ??
        )
      )
    elapsed
    )
  )

(defglobalconstant EE_SECONDS_PER_TICK (/ 1.0 3000000)) ;; 300MHz is a "decent enough" estimate
(defmacro cpu-ticks-to-seconds (ticks)
  `(* ,EE_SECONDS_PER_TICK ,ticks)
  )
(defun stopwatch-elapsed-seconds ((obj stopwatch))
  "Returns the elapsed time so far (in seconds) of a stopwatch"
  (cpu-ticks-to-seconds (stopwatch-elapsed-ticks obj))
  )