学び直し20日目：4章 機械語⑥（4章完了）
記録
IO操作について、、、写経。
github.com
「描画位置の初期化」「押されたかどうか判定して色を設定」「設定された色で範囲をすべて塗りつぶす」みたいな感じだった（はず）。飽きてきちゃったので先に進む。
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. (INIT) // Initialize the SCREEN address @SCREEN D=A @addr M=D // Choice black or white if the key is pressed or not. @KBD D=M // Pressed key -> IFPRESS, not pressed key -> ELSE(wait input) @IFPRESS D;JGT @ELSE 0;JMP (IFPRESS) @color M=-1 // color=-1 -> black @ENDIF 0;JMP (ELSE) @color M=0 // color=0 -> white (ENDIF) (LOOP) // Fill screen @color D=M @addr A=M M=D // addr <- color @addr M=M+1 @8192 D=A @SCREEN D=D+A @addr D=D-M @LOOP D;JGT @INIT 0;JMP
