装配计算器无法获取输入并通过程序工作

Question

我一直在用汇编语言开发这个计算器，但我不知道我做错了什么。它输出的是第一个字符串，但我认为此后它不会得到我的输入。 我将附上代码，以便您查看。

.ORIG x3000
; Strings used in the program

num_temp2      .FILL     #0
num_temp      .FILL     #0

; Program starts here


inputFirstNum  .STRINGZ "Input the first number you would like to use: "

ContProgram
    JSR ClearReg
    
    LEA R0, inputFirstNum
    PUTS
    JSR GetInput
    LD R1, num_temp

    
    LEA R0, inputOpp
    PUTS
    GETC
    ST R0, num_temp
    LD R0, num_temp
    JSR DecodeOperation
    
    LEA R0, inputSecNum
    PUTS
    JSR GetInput
    LD R2, num_temp



; Definitions for operation codes
codesArray    .FILL     #-43  ; '+'
              .FILL     #-45  ; '-'
              .FILL     #-42  ; '*'
              .FILL     #-47  ; '/'


GetInput
    AND R3, R3, #0        ; Clear R3 for digit count
    AND R4, R4, #0        ; Clear R4 for accumulated number
InputLoop
    GETC                  ; Read character into R0
    OUT                   ; Echo character
    ADD R5, R0, R6        ; Subtract 48 by adding R6 (which contains -48)
    BRn InputDone         ; Break loop if input is not a digit
    ; Perform R4 = R4 * 10 + R5 using repeated addition
    AND R6, R6, #0        ; Clear R6 to use as temporary register for sum
    LD R7, ten            ; Load the constant 10 into R7
    ADD R2, R4, #0        ; Copy R4 to R2 for repeated addition
MultiplyByTen
    ADD R6, R6, R2        ; Accumulate R4 into R6, 10 times
    ADD R7, R7, #-1       ; Decrement the counter
    BRp MultiplyByTen     ; Repeat until counter is zero
    ADD R4, R6, R5        ; Add the new digit to the accumulated result in R6
    ADD R3, R3, #1        ; Increment digit count
    BR InputLoop
InputDone
    ST R4, num_temp2       ; Store the number
    RET
    
    
ADDITION
    ADD R4, R1, R2
    BR OPERATION_FINISHED
    
SUBTRACTION
    NOT R2, R2
    ADD R2, R2, #1
    ADD R4, R1, R2
    BR OPERATION_FINISHED
    
MULTIPLY
    AND R3, R3, #0
    AND R4, R2 #0
MULTIPLY_LOOP
    BRz DONE_MULTIPLY
    ADD R3, R3, R1
    ADD R4, R4, #-1
    BRnp MULTIPLY_LOOP
DONE_MULTIPLY
    BRnzp OPERATION_FINISHED

DIVIDE
    AND R3, R3, #0
    AND R4, R1, #0
DIVIDE_LOOP
    NOT R5, R2
    ADD R5, R5, #1
    ADD R6, R4, R5
    BRn DIVIDE_DONE
    ADD R4, R4, R5
    ADD R3, R3, #1
    BRnzp DIVIDE_LOOP
DIVIDE_DONE
    BRnzp OPERATION_FINISHED


DecodeOperation
    LD R3, codesArray     ; Load base address of codesArray
    ADD R4, R0, #0        ; Copy operation character to R4
DecodeLoop
    LDR R5, R3, #0        ; Load operation code
    NOT R6, R5            ; Invert code for comparison
    ADD R6, R6, R4        ; Add inverted code to character
    BRz ExecuteOperation  ; Branch if zero (match)
    ADD R3, R3, #1        ; Move to next code
    BRnzp DecodeLoop      ; Continue if not out of codes
    RET


ExecuteOperation
    AND R3, R3, #0        ; Clear R3 for safe operation execution
    ADD R3, R5, #0        ; Copy operation code to R3 for checking
    BRz ADDITION          ; Branch if R3 is 0 (addition)
    BRp MULTIPLY_CHECK    ; Check further if it's multiplication or division
    BRn SUBTRACTION       ; Branch if R3 is negative (subtraction)

MULTIPLY_CHECK
    ADD R3, R3, #-2       ; Adjust R3 to check for multiplication or division
    BRz MULTIPLY
    BRp DIVIDE


    
STOP_PROGRAM
    TRAP x25

resultMsg      .STRINGZ "The answer is: "

OPERATION_FINISHED
    LEA R0, resultMsg
    PUTS
    ADD R0, R4, #0        ; Assuming R4 holds the result
    OUT
    LEA R0, continue
    PUTS
    GETC
    LD R6, NEG_ONE_TEN    ; Load -110 into R6 before comparison
    ADD R0, R0, R6        ; Subtract 110 from user input to check against 'n'
    BRz STOP_PROGRAM      ; If 'n', halt the program
    BRnzp ContProgram     ; Otherwise, jump back to start if not 'n'


ClearReg
    AND R1, R1, #0
    AND R2, R2, #0
    AND R3, R3, #0    
    AND R4, R4, #0
    AND R5, R5, #0
    AND R6, R6, #0
    RET

ten .FILL #10
NEG_FORTYEIGHT .FILL #-48
NEG_ONE_TEN .FILL #-110


inputSecNum    .STRINGZ "Input the second number you would like to use: "
debugMsg1      .STRINGZ "\nDebug: First number loaded\n"
debugMsg2      .STRINGZ "\nDebug: Operation decoded\n"
inputOpp       .STRINGZ "Input operation you would like to use '+, -, *, /': "
continue       .STRINGZ "Would you like to continue? (y/n): "

.END

我尝试了很多不同的方法来解决这个问题，但到目前为止没有任何效果。

Answer 1

首先出现的两个错误：

• 在

  InputLoop

  有
  

      ADD R5, R0, R6        ; Subtract 48 by adding R6 (which contains -48)

  
  - 但尽管有评论，R6 并不包含 -48。
• 还有

  GETC

  和

  OUT

  陷阱会覆盖 R7 中的返回地址；你必须从某个地方保存并恢复它。