# HG changeset patch
# User Steve Losh <steve@stevelosh.com>
# Date 1479261704 0
# Node ID f7f47291a61aca73fb06dffeb1d35d32b95c1b81
# Parent  d7119e2cc512952a12c547c56170a467b884b3a8
Start writing this thing I guess

diff -r d7119e2cc512 -r f7f47291a61a .lispwords
--- a/.lispwords	Tue Nov 15 23:12:46 2016 +0000
+++ b/.lispwords	Wed Nov 16 02:01:44 2016 +0000
@@ -0,0 +1,1 @@
+(1 macro-map)
diff -r d7119e2cc512 -r f7f47291a61a src/emulator.lisp
--- a/src/emulator.lisp	Tue Nov 15 23:12:46 2016 +0000
+++ b/src/emulator.lisp	Wed Nov 16 02:01:44 2016 +0000
@@ -3,6 +3,286 @@
 (setf *print-length* 10)
 (setf *print-base* 10)
 (declaim (optimize (speed 1) (safety 3) (debug 3)))
-; (declaim (optimize (speed 3) (safety 0) (debug 0)))
+(declaim (optimize (speed 3) (safety 0) (debug 3)))
+
+
+;;;; Types --------------------------------------------------------------------
+(deftype int8 () '(unsigned-byte 8))
+(deftype int12 () '(unsigned-byte 12))
+(deftype int16 () '(unsigned-byte 16))
+
+(deftype basic-array (element-type size)
+  `(simple-array ,(upgraded-array-element-type element-type) (,size)))
+
+(deftype stack (size)
+  `(vector ,(upgraded-array-element-type 'int12) ,size))
+
+
+;;;; Utils --------------------------------------------------------------------
+(declaim (inline nibble not= +_8 -_8))
+
+(defun make-simple-array (element-type size &rest args)
+  (apply #'make-array size
+         :adjustable nil
+         :fill-pointer nil
+         :element-type element-type
+         args))
+
+(defun nibble (position integer)
+  (ldb (byte 4 (* position 4)) integer))
+
+(defun not= (x y)
+  (not (= x y)))
+
+(defun +_8 (x y)
+  (let ((result (+ x y)))
+    (values (ldb (byte 8 0) result)
+            (if (> result 255) 1 0))))
+
+(defun -_8 (x y)
+  (let ((result (- x y)))
+    (values (ldb (byte 8 0) result)
+            (if (> x y) 1 0))))
+
+
+(defmacro macro-map ((lambda-list items) &rest body)
+  (with-gensyms (macro)
+    `(macrolet ((,macro ,(ensure-list lambda-list) ,@body))
+      ,@(iterate (for item :in items)
+                 (collect `(,macro ,@(ensure-list item)))))))
+
+
+;;;; Data ---------------------------------------------------------------------
+(defstruct chip
+  (memory (make-simple-array 'int8 4096)
+          :type (basic-array int8 4096)
+          :read-only t)
+  (registers (make-simple-array 'int8 16)
+             :type (basic-array int8 16)
+             :read-only t)
+  (video (make-simple-array 'fixnum #.(* 64 32))
+         :type (basic-array fixnum #.(* 64 32))
+         :read-only t)
+  (video-dirty t :type boolean)
+  (keys (make-simple-array 'boolean 16)
+        :type (basic-array boolean 16)
+        :read-only t)
+  (index 0 :type int16)
+  (program-counter 0 :type int12)
+  (delay-timer 0 :type int8)
+  (sound-timer 0 :type int8)
+  (random-state (make-random-state t)
+                :type random-state
+                :read-only t)
+  (stack (make-array 16
+           :adjustable nil
+           :fill-pointer 0
+           :element-type 'int12)
+         :type (stack 16)))
+
+(define-with-macro chip
+  memory registers video keys
+  index program-counter
+  delay-timer sound-timer
+  random-state
+  video-dirty
+  stack)
+
+
+;;;; Opcodes ------------------------------------------------------------------
+(defun parse-opcode-argument-bindings (argument-list)
+  (flet ((normalize-arg (arg)
+           (destructuring-bind (symbol &optional (nibbles 1))
+               (ensure-list arg)
+             (list symbol nibbles))))
+    (iterate
+      (for (symbol nibbles) :in (mapcar #'normalize-arg argument-list))
+      (for position :first 3 :then (- position nibbles))
+      (when (not (eql symbol '_))
+        (collect `(,symbol (ldb (byte ,(* nibbles 4)
+                                      ,(* position 4))
+                                opcode)))))))
+
+(defmacro define-opcode (name argument-list &body body)
+  `(progn
+    (declaim (ftype (function (chip int16)
+                              (values null &optional))
+                    ,name))
+    (defun ,name (chip opcode)
+      (declare (ignorable opcode))
+      (with-chip (chip)
+        (macrolet ((register (index)
+                     `(aref registers ,index)))
+          (let ,(parse-opcode-argument-bindings argument-list)
+            ,@body))
+        nil))))
 
 
+(macro-map                                              ;; LD ...
+    ((name arglist destination source)
+     ((op-ld-i<imm   (_ (value 3))   index         value)
+      (op-ld-reg<imm (_ r (value 2)) (register r)  value)
+      (op-ld-reg<reg (_ rx ry _)     (register rx) (register ry))
+      (op-ld-reg<dt  (_ r _ _)       (register r)  delay-timer)
+      (op-ld-dt<reg  (_ r _ _)       delay-timer   (register r))
+      (op-ld-st<reg  (_ r _ _)       sound-timer   (register r))))
+  `(define-opcode ,name ,arglist
+    (setf ,destination ,source)
+    (incf program-counter 2)))
+
+(define-opcode op-cls ()                                ;; CLS
+  (fill video 0)
+  (setf video-dirty t)
+  (incf program-counter 2))
+
+(define-opcode op-jp (_ (target 3))                     ;; JP addr
+  (setf program-counter target))
+
+(define-opcode op-call (_ (target 3))                   ;; CALL addr
+  (vector-push program-counter stack)
+  (setf program-counter target))
+
+(define-opcode op-ret ()                                ;; RET
+  (setf program-counter (vector-pop stack)))
+
+(macro-map                                              ;; ADD/SUB
+    ((name op source-arg source-expr)
+     ((op-add-reg<imm +_8 (immediate 2) immediate)
+      (op-add-reg<reg +_8 (ry 1) (register ry))
+      (op-sub-reg<reg -_8 (ry 1) (register ry))))
+  `(define-opcode ,name (_ rx ,source-arg)
+    (multiple-value-bind (result carry)
+        (,op (register rx) ,source-expr)
+      (setf (register rx) result
+            (register #xF) carry))
+    (incf program-counter 2)))
+
+(define-opcode op-subn-reg<reg (_ rx ry)                ;; SUBN
+    (multiple-value-bind (result carry)
+        (-_8 (register ry) (register rx)) ; subtraction order is swapped for SUBN
+      (setf (register rx) result
+            (register #xF) carry))
+    (incf program-counter 2))
+
+(macro-map                                              ;; SE/SNE
+    ((name test x-arg y-arg)
+     ((op-se-reg-imm  =    (r 1) (immediate 2))
+      (op-sne-reg-imm not= (r 1) (immediate 2))
+      (op-se-reg-reg  =    (rx 1) (ry 1))
+      (op-sne-reg-reg not= (rx 1) (ry 1))))
+  `(define-opcode ,name (_ ,x-arg ,y-arg)
+    (incf program-counter
+          (if (,test ,(car x-arg) ,(car y-arg)) 4 2))))
+
+(macro-map                                              ;; AND/OR/XOR
+    ((name function)
+     ((op-or logior)
+      (op-and logand)
+      (op-xor logxor)))
+  `(define-opcode ,name (_ destination source _)
+    (zapf (register destination)
+          (,function % (register source)))
+    (incf program-counter 2)))
+
+(define-opcode op-rnd (_ r (mask 2))                    ;; RND
+  (setf (register r)
+        (logand (random 256 random-state) mask))
+  (incf program-counter 2))
+
+(define-opcode op-skp (_ r _ _)                         ;; SKP
+  (incf program-counter (if (aref keys (register r)) 4 2)))
+
+(define-opcode op-sknp (_ r _ _)                        ;; SKNP
+  (incf program-counter (if (not (aref keys (register r))) 4 2)))
+
+(define-opcode op-ld-mem<regs (_ n _ _)                 ;; LD [I] < V_n
+  (replace memory registers :start1 index :end2 n)
+  (incf program-counter 2))
+
+(define-opcode op-ld-regs<mem (_ n _ _)                 ;; LD V_n < [I]
+  (replace registers memory :end1 n :start2 index)
+  (incf program-counter 2))
+
+
+;;;; Keyboard -----------------------------------------------------------------
+(defun keydown (chip key)
+  (with-chip (chip)
+    (setf (aref keys key) t)))
+
+(defun keyup (chip key)
+  (with-chip (chip)
+    (setf (aref keys key) nil)))
+
+
+;;;; Graphics -----------------------------------------------------------------
+
+;;;; Main ---------------------------------------------------------------------
+(defun load-rom (chip filename)
+  (replace (chip-memory chip) (read-file-into-byte-vector filename)
+           :start1 #x200))
+
+(defun emulate-cycle (chip)
+  (with-chip (chip)
+    (let ((opcode (logior (ash (aref memory program-counter) 8)
+                          (aref memory (1+ program-counter)))))
+      (macrolet ((call (name) `(,name chip opcode)))
+        (case (logand #xF000 opcode)
+          (#x0 (ecase opcode
+                 (#x00E0 (call op-cls))
+                 (#x00EE (call op-ret))))
+          (#x1 (call op-jp))
+          (#x2 (call op-call))
+          (#x3 (call op-se-reg-imm))
+          (#x4 (call op-sne-reg-imm))
+          (#x5 (ecase (logand #x000F opcode)
+                 (#x0 (call op-se-reg-reg))))
+          (#x6 (call op-ld-reg<imm))
+          (#x7 (call op-add-reg<imm))
+          (#x8 (ecase (logand #x000F opcode)
+                 (#x0)
+                 (#x1)
+                 (#x2)
+                 (#x3)
+                 (#x4)
+                 (#x5)
+                 (#x6)
+                 (#x7)
+                 (#xE)))
+          (#x9 (ecase (logand #x000F opcode)
+                 (#x0)))
+          (#xA (call op-ld-i<imm))
+          (#xB)
+          (#xC (call op-rnd))
+          (#xD)
+          (#xE (ecase (logand #x00FF opcode)
+                 (#x9E (call op-skp))
+                 (#xA1 (call op-sknp))))
+          (#xF (ecase (logand #x00FF opcode)
+                 (#x07 (call op-ld-reg<dt))
+                 (#x0A)
+                 (#x15 (call op-ld-dt<reg))
+                 (#x18 (call op-ld-st<reg))
+                 (#x1E)
+                 (#x29)
+                 (#x33)
+                 (#x55 (call op-ld-mem<regs))
+                 (#x65 (call op-ld-regs<mem)))))))))
+
+
+(defun draw-graphics (chip))
+(defun handle-keys (chip))
+
+(defparameter *running* t)
+
+(defun run ()
+  (let ((chip (make-chip)))
+    (setf *running* t)
+    ;; init
+    ;; load rom
+    (iterate
+      (while *running*)
+      (emulate-cycle chip)
+      (handle-keys chip)
+      )
+    )
+  )