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Fill.asm
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Fill.asm
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// 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.
// 24576为键盘的地址 16384-24575 刚好8K 为屏幕的地址
@24575
D = A
// R0存储屏幕最大地址
@0
M = D
// R1存储屏幕当前地址
@SCREEN
D = A
@1
M = D
(LOOP)
@KBD
D = M
@FILL
D;JGT
@CLEAR
0;JMP
(FILL)
// 判断屏幕是否为满
@0
D = M
@1
D = D - M
@LOOP
D;JLT
@1
// 缓存当前地址
D = M
// 将当前地址推入A
A = M
// 将地址对应的屏幕位置变黑
// 如果使用 1,翻译成二进制是 0000000000000001
// -1 翻译成二进制是 1111111111111111
// 如果表示在屏幕上,1 有 15 位是空白的,1位是黑的
// -1 则屏幕上的 16 位全是黑色
M = -1
// 当前地址+1
@1
M = D + 1
@LOOP
0;JMP
(CLEAR)
// 判断屏幕是否为空
@SCREEN
D = A
@1
D = D - M
@LOOP
D;JGT
@1
// 缓存当前地址
D = M
// 将当前地址推入A
A = M
// 将地址对应的屏幕位置变白
M = 0
// 当前地址-1
@1
M = D - 1
@LOOP
0;JMP