计划说明
我使用.BLKW为用户输入的每个字符分配20个位置，现在，我只想显示用户在第一个提示输入的字符串。 （这将是一个猪拉丁语翻译，因此第二个提示;但是现在我只想看看我是否可以打印出用户输入）
问题
问题在于，当我运行它时，我会在最后获得额外的字符。
例如：
English Word: apple
Pig-Latin Word: apple
English Word: at
Pig-Latin Word: atple
English Word: set
Pig-Latin Word: setle
我的计划
.ORIG x3000
START ST R1,SAVER1
ST R2,SAVER2
ST R3,SAVER3
LD R5,ENTER
REPEAT LEA R0,PROMPT ; loading the starting address of prompt
PUTS ; displays PROMPT on screen
LEA R4,ENGLWORD ; sets aside memory locations for typed characters
INPUT GETC ; now that user has typed, read char into R0
ADD R6,R5,R0 ; adds the negative value of the ASCII enter key code to the input character
BRz PIGPROMPT ; if the sum of the ASCII codes from step before is 0, that means user pressed enter so go to PIGPROMPT
OUT ; write char in R0 to console
STR R0,R4,#0 ; store typed character into memory location
ADD R4,R4,#1 ; increment memory location so you write next character to the next location
BRnzp INPUT ; break no matter what to the INPUT step to receive next typed character
PIGPROMPT LEA R0,PIG ; loads starting address of pig latin prompt
PUTS ; displays pig latin prompt on screen
LEA R0,ENGLWORD
PUTS
BRnzp REPEAT
LD R1,SAVER1 ; restore R1 to original value
LD R2,SAVER2 ; restore R2 to original value
LD R3,SAVER3 ; restore R3 to original value
HALT
SAVER1 .BLKW 1 ; allocates 1 memory location for SAVER1
SAVER2 .BLKW 1 ; allocates 1 memory location for SAVER2
SAVER3 .BLKW 1 ; allocates 1 memory location for SAVER3
ENGLWORD .BLKW #20
ENTER .FILL xFFF6 ; the negative value of the ASCII code for the enter key
NEWLINE .FILL x000A
PROMPT .STRINGZ "\nEnglish Word: " ; initializes a sequence of stringLength+1 memory locations to hold string
PIG .STRINGZ "\nPig-Latin Word: "
DSR .FILL xFE04
DDR .FILL xFE06
KBSR .FILL xFE00
KBDR .FILL xFE02
.END
尝试解决方案
我在想，问题是R4在整个程序中保存了第一个用户输入的字符串。所以对于一个解决方案，我想在显示R4之后清除它，以便它准备好接受下一个用户输入。有谁知道我会怎么做？
答案 0 :(得分：0)
这里的关键是PUTS如何工作 - 它打印从R0地址开始的所有字符，直到它达到0（'\ 0'而不是'0'）。
第一次运行时，内存将包含['A'，'P'，'P'，'L'，'E']，如果你在加载时没有随机化内存内容，则后跟零该程序。这意味着PUTS调用将返回“APPLE”。当您输入新单词时，它不会清除该内存，因此输入“at”将导致['A'，'T'，'P'，'L'，'E']和您的打印程序将打印“ATPLE”。
为了正确完成单词，您需要在要打印的最后一个字符后的元素中添加'\ 0'（a.k.a。0）。换句话说，如果你的记忆包含['A'，'T'，'\ 0'，'L'，'E']，你的打印例程将打印“AT”。
答案 1 :(得分：0)
Aqua的权利，PUTs命令正在寻找一个零来停止在屏幕上打印字符。我在PIGPROMPT之后添加了两行代码，它似乎按预期工作。
修：
.ORIG x3000
START ST R1,SAVER1
ST R2,SAVER2
ST R3,SAVER3
LD R5,ENTER
REPEAT LEA R0,PROMPT ; loading the starting address of prompt
PUTS ; displays PROMPT on screen
LEA R4,ENGLWORD ; sets aside memory locations for typed characters
INPUT GETC ; now that user has typed, read char into R0
ADD R6,R5,R0 ; adds the negative value of the ASCII enter keycode to the input character
BRz PIGPROMPT ; if the sum of the ASCII codes from step before is 0, that means user pressed enter so go to PIGPROMPT
OUT ; write char in R0 to console
STR R0,R4,#0 ; store typed character into memory location
ADD R4,R4,#1 ; increment memory location so you write next character to the next location
BRnzp INPUT ; break no matter what to the INPUT step to receive next typed character
PIGPROMPT AND R0, R0, #0 ; clear R0
STR R0,R4,#0 ; store typed character into memory location
LEA R0,PIG ; loads starting address of pig latin prompt
PUTS ; displays pig latin prompt on screen
LEA R0,ENGLWORD
PUTS
BRnzp REPEAT
LD R1,SAVER1 ; restore R1 to original value
LD R2,SAVER2 ; restore R2 to original value
LD R3,SAVER3 ; restore R3 to original value
HALT
SAVER1 .BLKW 1 ; allocates 1 memory location for SAVER1
SAVER2 .BLKW 1 ; allocates 1 memory location for SAVER2
SAVER3 .BLKW 1 ; allocates 1 memory location for SAVER3
ENGLWORD .BLKW #20
ENTER .FILL xFFF6 ; the negative value of the ASCII code for the enter key
NEWLINE .FILL x000A
PROMPT .STRINGZ "\nEnglish Word: " ; initializes a sequence of stringLength+1 memory locations to hold string
PIG .STRINGZ "\nPig-Latin Word: "
DSR .FILL xFE04
DDR .FILL xFE06
KBSR .FILL xFE00
KBDR .FILL xFE02
.END
我所做的就是存储一个＆＃39; 0＆＃39;用户字符串末尾的值，当调用PUT时，它将停止在零值。