hw9.md

第十週

fill.asm

// 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.
(RESTART)
@SCREEN
D=A
@0
M=D	//PUT SCREEN START LOCATION IN RAM0
(KBDCHECK)
@KBD
D=M
@BLACK
D;JGT
@WHITE
D;JEQ
@KBDCHECK
0;JMP
(BLACK)
@1
M=-1
@CHANGE
0;JMP
(WHITE)
@1
M=0
@CHANGE
0;JMP
(CHANGE)
@1
D=M
@0
A=M
M=D
@0
D=M+1
@KBD
D=A-D
@0
M=M+1
A=M
@CHANGE
D;JGT
@RESTART
0;JMP