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timers.lisp
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(defpackage #:psx-timers
(:nicknames #:timers)
(:use :cl)
(:export #:timers #:make-timers #:read-timers #:write-timers
#:advance-timers #:timers-exception-callback
#:sync-timers #:init-timers #:timers-sync-callback))
(in-package :psx-timers)
(declaim (optimize (speed 3) (safety 1)))
(defstruct mode
(synchronization-enabled nil :type boolean)
(synchronization-mode 0 :type (unsigned-byte 2))
(zero-counter-condition :at-max :type keyword)
(irq-at-target-value nil :type boolean)
(irq-at-max-value nil :type boolean)
(irq-frequency :once :type keyword)
(irq-style :pulse :type keyword)
; Each different timer has a different meaning for this selection...
(clock-source 0 :type (integer 0 3))
(clock-source-callback
(lambda () 0)
:type (function () (unsigned-byte 62)))
(cycles-till-value
(lambda (value) value)
:type (function ((unsigned-byte 62))
(unsigned-byte 62)))
(reached-max-value nil :type boolean)
(reached-target-value nil :type boolean)
(fired-irq nil :type boolean))
(defstruct timer
(identifier :timer0 :type keyword)
(source-sync-epoch 0 :type (unsigned-byte 62))
(current-value 0 :type (unsigned-byte 16))
(target-value 0 :type (unsigned-byte 16))
(mode (make-mode) :type mode)
(synchronization-modes 0 :type (integer 0 3)))
(declaim (ftype (function (mode)
(unsigned-byte 16))
mode-to-word))
(defun mode-to-word (mode)
(logior
(ash (if (mode-synchronization-enabled mode) 1 0) 0)
(ash (mode-synchronization-mode mode) 1)
(ash (if (eql (mode-zero-counter-condition mode) :at-target) 1 0) 3)
(ash (if (mode-irq-at-target-value mode) 1 0) 4)
(ash (if (mode-irq-at-max-value mode) 1 0) 5)
(ash (if (eql (mode-irq-frequency mode) :repeat) 1 0) 6)
(ash (if (eql (mode-irq-style mode) :toggle) 1 0) 7)
(ash (mode-clock-source mode) 8)
(ash (if (has-irq mode) 0 1) 10)
(ash (if (mode-reached-target-value mode) 1 0) 11)
(ash (if (mode-reached-max-value mode) 1 0) 12)))
(declaim (ftype (function ((unsigned-byte 16))
mode)
word-to-mode))
(defun word-to-mode (word)
(make-mode
:synchronization-enabled (ldb-test (byte 1 0) word)
:synchronization-mode (ldb (byte 2 1) word)
:zero-counter-condition (if (ldb-test (byte 1 3) word) :at-target :at-max)
:irq-at-target-value (ldb-test (byte 1 4) word)
:irq-at-max-value (ldb-test (byte 1 5) word)
:irq-frequency (if (ldb-test (byte 1 6) word) :repeat :once)
:irq-style (if (ldb-test (byte 1 7) word) :toggle :pulse)))
(declaim (ftype (function (mode) boolean) has-irq))
(defun has-irq (mode)
(or (and (mode-reached-target-value mode)
(mode-irq-at-target-value mode))
(and (mode-reached-max-value mode)
(mode-irq-at-max-value mode))))
(defstruct timers
; TODO(Samantha): Figure out why this being 64 bit causes SBCL optimization
; notes to complain.
(clock 0 :type (unsigned-byte 62))
; TODO(Samantha): Add dotclock and hblank callbacks.
(sync-callback
(lambda (clock) (declare (ignore clock)))
:type (function ((unsigned-byte 62))))
(system-clock-callback
(lambda () 0)
:type (function () (unsigned-byte 62)))
(exception-callback
(lambda (keyword) (declare (ignore keyword)) 0)
:type (function (keyword) (unsigned-byte 9)))
(timers
(make-array 3
:element-type 'timer
:initial-contents (vector
(make-timer :identifier :timer0)
(make-timer :identifier :timer1)
(make-timer :identifier :timer2)))
:type (simple-array timer (3))))
(declaim (ftype (function (timers timer (integer 0 3)))
set-clocksource))
(defun set-clocksource (timers timer source)
(let* ((mode (timer-mode timer))
(cycles-till-value
(lambda (value)
(- (the (unsigned-byte 62) value)
(funcall
(mode-clock-source-callback mode))))))
(declare ((function ((unsigned-byte 62))
(unsigned-byte 62))
cycles-till-value))
(ecase (timer-identifier timer)
(:timer0
(ecase source
; System clock
(0 (setf (mode-clock-source-callback mode)
(timers-system-clock-callback timers))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; Dotclock
; TODO(Samantha): Change this to the proper source
(1 (setf (mode-clock-source-callback mode)
(lambda () (ceiling (* 1.57142857143 (funcall (timers-system-clock-callback timers))))))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; System clock
(2 (setf (mode-clock-source-callback mode)
(timers-system-clock-callback timers))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; Dot clock
; TODO(Samantha): Change this to the proper source
(3 (setf (mode-clock-source-callback mode)
(lambda () (ceiling (* 1.57142857143 (funcall (timers-system-clock-callback timers))))))
(setf (mode-cycles-till-value mode)
cycles-till-value))))
(:timer1
(ecase source
; System clock
(0 (setf (mode-clock-source-callback mode)
(timers-system-clock-callback timers))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; Hblank
; TODO(Samantha): Change this to the proper source
(1 (setf (mode-clock-source-callback mode)
(lambda () (ceiling (/ (* 1.57142857143 (funcall (timers-system-clock-callback timers))) 3406))))
(setf (mode-cycles-till-value mode)
(lambda (value)
(ldb
(byte 62 0)
(* 3406 (funcall cycles-till-value value))))))
; System clock
(2 (setf (mode-clock-source-callback mode)
(timers-system-clock-callback timers))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; Hblank
; TODO(Samantha): Change this to the proper source
(3 (setf (mode-clock-source-callback mode)
(lambda () (ceiling (/ (* 1.57142857143 (funcall (timers-system-clock-callback timers))) 3406))))
(setf (mode-cycles-till-value mode)
(lambda (value)
(ldb
(byte 62 0)
(* 3406 (funcall cycles-till-value value))))))))
(:timer2
(ecase source
; System clock
(0 (setf (mode-clock-source-callback mode)
(timers-system-clock-callback timers))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; System clock
(1 (setf (mode-clock-source-callback mode)
(timers-system-clock-callback timers))
(setf (mode-cycles-till-value mode)
cycles-till-value))
; System clock div 8
(2 (setf (mode-clock-source-callback mode)
(lambda ()
(truncate (/ (funcall
(timers-system-clock-callback timers))
8.0))))
(setf (mode-cycles-till-value mode)
(lambda (value)
(ldb
(byte 62 0)
(* 8 (funcall cycles-till-value value))))))
; System clock div 8
(3 (setf (mode-clock-source-callback mode)
(lambda ()
(truncate (/ (funcall
(timers-system-clock-callback timers))
8.0))))
(setf (mode-cycles-till-value mode)
(lambda (value)
(ldb
(byte 62 0)
(* 8 (funcall cycles-till-value value)))))))))
(setf (timer-source-sync-epoch timer)
(funcall (mode-clock-source-callback mode)))
(setf (mode-clock-source mode)
source))
(values))
(declaim (ftype (function (timer)
boolean)
has-repeat-irq))
(defun has-repeat-irq (timer)
(or
(and (= (timer-current-value timer) (timer-target-value timer))
(mode-irq-at-target-value (timer-mode timer)))
(and (= (timer-current-value timer) #xFFFF)
(mode-irq-at-max-value (timer-mode timer)))))
(declaim (ftype (function (timers timer)
(unsigned-byte 8))
generate-irq))
(defun generate-irq (timers timer)
(if (eql (mode-irq-frequency (timer-mode timer)) :repeat)
(when (has-repeat-irq timer)
(funcall (timers-exception-callback timers) (timer-identifier timer)))
(when (and (has-irq (timer-mode timer))
(not (mode-fired-irq (timer-mode timer))))
(funcall (timers-exception-callback timers) (timer-identifier timer))
(setf (mode-fired-irq (timer-mode timer)) t)))
0)
(declaim (ftype (function (timers timer))
sync-timer))
(defun sync-timer (timers timer)
(let ((cycles-since-sync (- (funcall (mode-clock-source-callback
(timer-mode timer)))
(timer-source-sync-epoch timer)))
(old-value (timer-current-value timer))
(mode (timer-mode timer)))
; TODO(Samantha): Sync modes?
; Move the timer's last sync forwards
(setf (timer-source-sync-epoch timer)
(funcall (mode-clock-source-callback
mode)))
(setf (timer-current-value timer)
(ldb (byte 16 0) (+ cycles-since-sync old-value)))
(when (<= (1+ old-value)
#xFFFF
(timer-current-value timer))
(setf (mode-reached-max-value mode)
t)
(when (mode-irq-at-max-value mode)
; TODO(Samantha): Pass the type of irq?
(generate-irq timers timer)))
(when (<= (1+ old-value)
(timer-target-value timer)
(timer-current-value timer))
(setf (mode-reached-target-value mode)
t)
(when (eql (mode-zero-counter-condition mode) :at-target)
(setf (timer-current-value timer)
(mod (ldb (byte 64 0)
(+ (timer-current-value timer)
cycles-since-sync))
(timer-target-value timer))))
(when (mode-irq-at-max-value mode)
; TODO(Samantha): Pass the type of irq?
(generate-irq timers timer)))
(values)))
(declaim (ftype (function (timer)
(unsigned-byte 62))
ticks-until-nece))
(defun ticks-until-necessary-sync (timer)
(funcall
(mode-cycles-till-value (timer-mode timer))
(+
(timer-source-sync-epoch timer)
(abs (min (if (< (- (timer-target-value timer)
(timer-current-value timer))
0)
#xFFFF
(- (timer-target-value timer)
(timer-current-value timer)))
(- #xFFFF
(timer-current-value timer)))))))
(declaim (ftype (function (timers))
init-timers))
(defun init-timers (timers)
(loop for timer across (timers-timers timers)
do (set-clocksource timers timer 0))
(values))
(declaim (ftype (function (timers))
sync-timers))
(defun sync-timers (timers)
(loop for timer across (timers-timers timers)
do (sync-timer timers timer))
(funcall (timers-sync-callback timers)
(min (ticks-until-necessary-sync (aref (timers-timers timers) 0))
(ticks-until-necessary-sync (aref (timers-timers timers) 1))
(ticks-until-necessary-sync (aref (timers-timers timers) 2))))
(values))
(declaim (ftype (function (timers (unsigned-byte 8))
(unsigned-byte 16))
read-timers))
(defun read-timers (timers offset)
(sync-timers timers)
(let ((timer (aref (timers-timers timers) (ldb (byte 2 4) offset))))
(case (ldb (byte 4 0) offset)
(0 (timer-current-value timer))
(4 (let ((mode (mode-to-word (timer-mode timer))))
(setf (mode-reached-max-value (timer-mode timer)) nil)
(setf (mode-reached-target-value (timer-mode timer)) nil)
(setf (mode-fired-irq (timer-mode timer)) nil)
mode))
(8 (timer-target-value timer))
(otherwise
(error "Invalid timer register index: #x~1,'0x with timer ~
number: #x~1,'0x"
(ldb (byte 4 0) offset) (ldb (byte 2 4) offset))))))
(declaim (ftype (function (timers (unsigned-byte 8) (unsigned-byte 32))
(unsigned-byte 16))
write-timers))
(defun write-timers (timers offset value)
(let ((timer (aref (timers-timers timers) (ldb (byte 2 4) offset)))
(value (ldb (byte 16 0) value)))
(case (ldb (byte 4 0) offset)
(0 (setf (timer-current-value timer) value))
; Writing to a timer's mode register causes the current value to
; be reset to 0.
(4 (setf (timer-current-value timer) #x0000)
(setf (timer-mode timer) (word-to-mode value))
(set-clocksource timers timer (ldb (byte 2 8) value)))
(8 (setf (timer-target-value timer) value))
(otherwise
(error "Invalid timer register index: #x~1,'0x with timer ~
number: #x~1,'0x"
(ldb (byte 4 0) offset) (ldb (byte 2 4) offset))))
(sync-timers timers)
value))