Minor memory map improvements, add .gitignore.

.gitignore

@@ -0,0 +1,2 @@
+*.fasl
+roms/

src/apu.lisp

@@ -2,5 +2,31 @@
 
 (defstruct apu
   "The Nintendo Audio Processing Unit."
-  (regs  (bytevector #x17)))
+  (pulse-1)
+  (pulse-2)
+  (triangle)
+  (noise)
+  (status))
 
+;;; KLUDGE: The APU also currently handles input requests. Cheating!
+(defun get-byte-apu% (addr)
+  (case addr
+    (#x4014 (format t "OAM DMA not yet implemented."))
+    (#x4016 (prog1 (get-state *pad*)
+              (next-state *pad*)))
+    (otherwise 0)))
+
+(defun (setf get-byte-apu%) (new-val addr)
+  (cond ((= addr #x4014) (format t "OAM DMA not yet implemented."))
+        ((= addr #x4016) (setf (pad-strobe *pad*) :a))
+        ((< addr #x4004) (update-pulse addr new-val 0))
+        ((< addr #x4008) (update-pulse addr new-val 1))
+        ((< addr #x400c) (update-triangle addr new-val))
+        ((< addr #x4010) (update-noise addr new-val))
+        ((= addr #x4015) (update-status new-val))
+        (t 0)))
+
+(defun update-pulse (addr val which))
+(defun update-triangle (addr val))
+(defun update-noise (addr val))
+(defun update-status (val))

src/input.lisp

@@ -54,14 +54,3 @@ the keypress of the event if it is of type :key-down-event."
     (:sdl-key-escape :quit)
     (t (alexandria:when-let (index (%keymap key))
          (setf (aref (pad-buttons pad) index) 1)))))
-
-(defun get-byte-input% (addr)
-  (case addr
-    (#x4015 (format t "OAM DMA not yet implemented."))
-    (#x4016 (prog1 (get-state *pad*)
-              (next-state *pad*)))
-    (otherwise 0)))
-
-(defun (setf get-byte-input%) (new-val addr)
-  (when (= addr #x4016)
-    (setf (pad-strobe *pad*) :a)))

src/mem.lisp

@@ -3,14 +3,14 @@
 (defun 6502:get-byte (addr)
   (cond ((< addr #x2000) (get-byte-ram% addr))
         ((< addr #x4000) (get-byte-ppu% addr))
-        ((< addr #x4018) (get-byte-input% addr))
+        ((= addr #x4016) (get-byte-input% addr))
         ((< addr #x8000) (format t "Cartridge RAM not yet implemented"))
         (t (get-mapper (nes-mapper *nes*) addr))))
 
 (defun (setf 6502:get-byte) (new-val addr)
   (cond ((< addr #x2000) (setf (get-byte-ram% addr) new-val))
         ((< addr #x4000) (setf (get-byte-ppu% addr) new-val))
-        ((< addr #x4018) (setf (get-byte-input% addr) new-val))
+        ((< addr #x4020) (setf (get-byte-apu% addr) new-val))
         ((< addr #x8000) (format t "Cartridge RAM not yet implemented"))
         (t (set-mapper (nes-mapper *nes*) addr new-val))))