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// This file is part of www.nand2tetris.org
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/04/Fill.asm
// Runs an infinite loop that listens to the keyboard input.
// When a key is pressed (any key), the program blackens the screen,
// i.e. writes "black" in every pixel;
// the screen should remain fully black as long as the key is pressed.
// 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.
(BEGIN)
@KBD
D=M
@BLACK
D;JNE
@WHITE
0;JMP
(BLACK)
@8191
D=A
@i
M=D
(LOOPB)
@i
D=M
@j
M=D
@SCREEN
D=A
@j
M=M+D
A=M
M=-1
@i
M=M-1
D=M
@LOOPB
D+1;JGT
@BEGIN
0;JMP
(WHITE)
@8191
D=A
@i
M=D
(LOOPW)
@i
D=M
@j
M=D
@SCREEN
D=A
@j
M=M+D
A=M
M=0
@i
M=M-1
D=M
@LOOPW
D+1;JGT
@BEGIN
0;JMP
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