M projects/04/fill/Fill.asm → projects/04/fill/Fill.asm

@@ -11,4 +11,64 @@ // When no key is pressed, the program clears the screen, i.e. writes
 // "white" in every pixel;
 // the screen should remain fully clear as long as no key is pressed.
 
-// Put your code here.+// Put your code here.
+
+// TODO: optimize better in the future
+
+(SET_SCREEN_PTR)
+    // R0 = SCREEN pointer
+    @SCREEN
+    D=A
+    @R0
+    M=D
+
+// TODO: fix infinitely incrementing screen pointer bug
+// end of screen: 0x5fff (dec 24575)
+
+(IS_KEYPRESSED)
+    // if R0 == 24575; goto SET_SCREEN_PTR
+    @R0
+    D=M
+    @24575
+    D=D-A
+    @SET_SCREEN_PTR
+    D;JEQ
+
+    // D=KBD, goto WHITE_SCREEN if D == 0
+    @KBD
+    D=M
+    @WHITE_SCREEN
+    D;JEQ
+
+(BLACK_SCREEN)
+    // *R0 = -1
+    @R0
+    A=M
+    M=-1
+
+    // ++R0
+    @R0
+    M=M+1
+
+    @IS_KEYPRESSED
+    0;JMP
+    // TODO: replace with D;JLT or something
+
+(WHITE_SCREEN)
+    // *R0 = 0
+    @R0
+    A=M
+    M=0
+
+    // ++R0
+    @R0
+    M=M+1
+
+    @IS_KEYPRESSED
+    0;JMP
+    // TODO: replace with D;JLT or something
+
+(END)
+    @END
+    0;JMP
+