Question

如何将用户的任何字符输入转换为相应的十进制值？我刚开始时遇到了麻烦。

该计划必须实现以下目标：

程序从键盘接受字符。
如果字符是数字（'0'到'9'）： a）将字符转换为其对应的十进制值。换句话说，'0'变为零，'1' 变为1，...'9'变为9.我们称之为值R（表示“游程长度”）。 b）等待另一个角色（使用GETC）。 c）将该角色的R副本打印到控制台。） d）返回步骤1.
否则，如果字符为Enter / Return（ASCII＃10）：将换行符（ASCII＃10）打印到控制台，并且回到第1步。
否则，如果角色是其他任何内容，则暂停该程序。

Answer 1

如上所述，问题有点不清楚：输入已经是十进制值。

如果你的意思是如何将输入转换为可以进行数学运算的二进制表示，那么基本上你从每个字符值中减去48（30h）以将每个数字转换为数值。

请参阅asciitable.com

如果有多个输入数字，则循环它们并将累加器乘以10，除了最后一个迭代。

Answer 2

你显然在这里问过同样的事情：program for LC3 Assembly language

如果您发布代码，将来会有所帮助。

我没有根据需要转换这种类型的问题，而是我做了一些检查以查看数字是什么并打印了一个等效的字符串。希望我的计划能给你一些想法：

.ORIG x3000 ; start at x3000 above system memory
LEA R0, CLASS   ; load address of string CLASS in R0
PUTS        ; use PUTS to output string to console
LEA R0, MYNAME  ; repeat steps for class template
PUTS
LEA R0, PRNUM
PUTS
LEA R0, NWLINE
PUTS

; now get a character from the user and echo it back
; using the prompts INPROM and OUTPROM
ASKINP  LEA R0, INPPROM
    PUTS
    GETC        ; get a character from the keyboard
    ADD R2,R0,#0    ; move the value in R0 to R2 for later comparisons

; PROCESS THE INPUT
; first figure out if they entered a non-printing character with ASCII code
; <32. If so, suppress the printing of the character and give the user the
; standard error that they have not entered a number. We do this by subtracting
; 33 from the input and if the CC is negative, it's a non-printing character. 
; For purposes of this program a space is considered a non-printing character.
    ADD R2, R2, #-15
    ADD R2, R2, #-15
    ADD R2, R2, #-3 ; subtracted 33, see if it's negative
    BRn XERR    ; if so branch to error message

; if we're still here, then it's a printable character and we continue here...
    OUT     ; echo the character back on the input line
    LEA R0, SPACE   ; need a space after the input
    PUTS
    AND R0, R0, #0  ; set the condition to zero again

; figure out what character the user entered, and we have already subtracted 33 from
; the entry. See if it's a ! and the user wants to end. If so, the CC
; will be Zero and we break to XDONE.
; if that's not it, subtract another 15 (for a total subtracted of 48) and 
; successively test to see if it's a number match. If there is no match, 
; then print out that the user has not made a correct entry

; now we subtracted 33 so if they entered ! we now have 0 in R2, subtract 0
; and test the CC to see if it's Zero.
    ADD R1, R2, #0
    BRz XDONE
; if we have not just branched, subtract another 15 and keep testing
    ADD R2, R2, #-15
    ADD R1, R2, #-9
    BRz XNINE
    ADD R1, R2, #-8
    BRz XEIGHT
    ADD R1, R2, #-7
    BRz XSEVEN
    ADD R1, R2, #-6
    BRz XSIX
    ADD R1, R2, #-5
    BRz XFIVE
    ADD R1, R2, #-4
    BRz XFOUR
    ADD R1, R2, #-3
    BRz XTHREE
    ADD R1, R2, #-2
    BRz XTWO
    ADD R1, R2, #-1
    BRz XONE
    ADD R1, R2, #0
    BRz XZERO
; not a quit signal or number, need to print out an error and start again
    BRnzp XERR

; here is the section that prints out the string related to the 
; number that was entered, by loading the string into R0 and
; using PUTS to print it out, then BReak back to the beginning
; of the input sequence and ask again. Pre-condition is that the
; user typed in a number for 0-9, if not they will get an error
; elsewhere in the program
XZERO   LEA R0, ZERO
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP  
XONE    LEA R0, ONE
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XTWO    LEA R0, TWO
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XTHREE  LEA R0, THREE
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XFOUR   LEA R0, FOUR
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XFIVE   LEA R0, FIVE
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XSIX    LEA R0, SIX
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XSEVEN  LEA R0, SEVEN
    PUTS
    LEA R0, NWLINE
    PUTS    
    BRnzp   ASKINP
XEIGHT  LEA R0, EIGHT
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XNINE   LEA R0, NINE
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XERR    LEA R0, INPERR
    PUTS
    LEA R0, NWLINE
    PUTS
    BRnzp   ASKINP
XDONE   LEA R0, DONE
    PUTS
    LEA R0, NWLINE
    PUTS
    HALT

; store the following strings with these labels
NWLINE  .STRINGZ    "\n"
SPACE   .STRINGZ    " "
CLASS   .STRINGZ    "CS2810\n"  
MYNAME  .STRINGZ    "James Lohse\n"
PRNUM   .STRINGZ    "Project 3\n"
BYEBYE  .STRINGZ    "Program execution terminated!\n"
INPPROM .STRINGZ    "Input a number 0-9: "
INPERR  .STRINGZ    "Error! You did not input a number."
DONE    .STRINGZ    "Done!"
ZERO    .STRINGZ    "zero"
ONE .STRINGZ    "one"
TWO .STRINGZ    "two"
THREE   .STRINGZ    "three"
FOUR    .STRINGZ    "four"
FIVE    .STRINGZ    "five"
SIX .STRINGZ    "six"
SEVEN   .STRINGZ    "seven"
EIGHT   .STRINGZ    "eight"
NINE    .STRINGZ    "nine "
    .END

LC3汇编语言程序

2 个答案: