检查输入的数字是否在0和9之间汇编

Question

我在用汇编语言编程，而且我对这门语言非常陌生。我正在使用Ubuntu中的yasm进行编程。我应该从用户那里获取输入，并判断他们的输入是偶数还是奇数。如果输入是奇数，我需要查看它是大于5还是小于5，然后，在完成所有操作之后，我需要确保用户想要再次输入。我很确定我已经记下了，只是在验证用户输入时遇到了问题。我在试着确保他们输入一个从0到9的数字。

下面是我为我的程序写的所有东西，我找不到哪里错了。当我尝试运行它时，我得到这个错误:浮点异常(核心转储)

; Data section, declaring variables
section .data
    output  dd  'Enter a single digit between 0 and 9'  ;1st output
    nl  db  0x0a                    
    opLen   equ $-output                                ;length of 1st output
    
    Go  equ 0x59                                        ;to check confirmation
    go  equ 0x79                                        ;to check confirmation
    
    rem dd  0xffff                                      ;empty remainder for modulo
    output1 dd  'You entered an even number'            ;output for even
    op1Len  equ $-output1                               ;even output length
    output2 dd  'You entered an odd number <= 5'        ;output for odd less or equal to 5
    op2Len  equ $-output2                               ;output length for first odd
    output3 dd  'you entered an odd number > 5'         ;output for odd more than 5
    op3Len  equ $-output3                               ;output length for second odd
    output4 dd  '...what?...'                           ;output for if the thing entered is not a number
    op4Len  equ $-output4                               ;else output length
    
    confirm dd  'go again? (y/n): '         ;confirmation message
    cLen    equ $-confirm                   ;confirmation message length
    
    divs    dd  2

section .bss
    input   dd  0xffff                      ;for user input
    again   dd  0xffff                      ;for second user input

section .text
global _start
_start: 
    call printOutput    ;prints first output
    call getInput       ;receives user input
    call checkNumZero   ;checks if number is greater than zero
    call checkEvenOdd   ;does the modulo operation on the number
    cmp dword [rem], 0  ;compares the remainder and 0
    je handleTrueEven   ;if remainder is zero, then the first message is outputted
    call isOdd          ;if the remainder isn't zero, it checks if it is greater or less than 5
    call goAgain        ;asks the user if they want to go again
    

printOutput:
    mov rax, 1
    mov rdi, 1
    mov rsi, output
    mov rdx, opLen
    syscall
    ret

getInput:
    mov rax, 0
    mov rdi, 0
    mov rsi, input
    mov rdx, 0xffff
    syscall
    ret

checkNumZero:
    cmp dword [input], '0'
    jbe checkNumNine
    call else

checkNumNine:
    cmp dword [input], '9'
    ja else
    ret

else:
    mov rax, 1
    mov rdi, 1
    mov rsi, output4
    mov rdx, op4Len
    syscall
    ret

checkEvenOdd:
    mov rax, 0
    mov eax, dword [input]
    div dword [divs]
    mov dword [rem], edx
    ret

handleTrueEven:
    mov rax, 1
    mov rdi, 1
    mov rsi, output1
    mov rdx, op1Len
    syscall
    ret

isOdd:
    cmp dword [input], 5
    jle lessThan
    call moreThan
    ret

lessThan:
    mov rax, 1
    mov rdi, 1
    mov rsi, output2
    mov rdx, op2Len
    syscall
    ret

moreThan:
    mov rax, 1
    mov rdi, 1
    mov rsi, output3
    mov rdx, op3Len
    syscall
    ret

goAgain:
    mov rax, 1
    mov rdi, 1
    mov rsi, confirm
    mov rdx, cLen
    syscall
    
    mov rax, 0
    mov rdi, 0
    mov rsi, again
    mov rdx, 0xffff
    syscall
    
    cmp dword [again], 0x79
    jne doneIf
    cmp dword [again], 0x59
    jne doneIf
    ret

doneIf:
    mov rax, 60
    mov rdi, 0
    syscall

Answer 1

为了纠正这个问题，我们做了几处更改，如下所示。

section .data
    output  dd  'Enter a single digit between 0 and 9'  ;1st output
    nl  db  0x0a                    
    opLen   equ $-output                ;length of 1st output
    
    rem dd  0xffff                  ;empty remainder for modulo
    output1 dd  'You entered an even number'        ;output for even
    nl1     db  0x0a
    op1Len  equ $-output1               ;even output length
    output2 dd  'You entered an odd number <= 5'    ;output for odd less or equal to 5
    nl2 db  0x0a
    op2Len  equ $-output2               ;output length for first odd
    output3 dd  'you entered an odd number > 5'     ;output for odd more than 5
    nl3     db  0x0a
    op3Len  equ $-output3               ;output length for second odd
    output4 dd  '...what?...'               ;output for if the thing entered is not a number
    nl4     db  0x0a
    op4Len  equ $-output4               ;else output length
    
    confirm dd  'go again? (y/n):'          ;confirmation message
    nl5     db  0x0a
    cLen    equ $-confirm               ;confirmation message length
    
    divs    db  2

section .bss
    input   resb    0xff                    ;for user input
    again   resb    0xff                    ;for second user input

section .text
global _start
_start: 
    call printOutput    ;prints first output
    call getInput       ;receives user input
    call checkNumZero   ;checks if number is greater than zero
    call checkEvenOdd   ;does the modulo operation on the number
    cmp byte [rem], 0       ;compares the remainder and 0
    je handleTrueEven   ;if remainder is zero, then the first message is outputted
    call isOdd      ;if the remainder isn't zero, it checks if it is greater or less than 5
    ;call goAgain       asks the user if they want to go again
    

printOutput:
    mov rax, 1
    mov rdi, 1
    mov rsi, output
    mov rdx, opLen
    syscall
    ret

getInput:
    mov rax, 0
    mov rdi, 0
    mov rsi, input
    mov rdx, 0xff
    syscall
    ret

checkNumZero:
    cmp byte [input], 0x30
        jae checkNumNine
        call else

checkNumNine:
        cmp byte [input], 0x39
        ja else
    ret

else:
    mov rax, 1
    mov rdi, 1
    mov rsi, output4
    mov rdx, op4Len
    syscall
    call goAgain

checkEvenOdd:
    mov al, byte [input]
    mov ah, 0
    div byte [divs]
    mov byte [rem], ah
    ret

handleTrueEven:
    mov rax, 1
    mov rdi, 1
    mov rsi, output1
    mov rdx, op1Len
    syscall
    call goAgain

isOdd:
    cmp byte [input], '5'
    jbe lessThan
    call moreThan
    call goAgain

lessThan:
    mov rax, 1
    mov rdi, 1
    mov rsi, output2
    mov rdx, op2Len
    syscall
    call goAgain

moreThan:
    mov rax, 1
    mov rdi, 1
    mov rsi, output3
    mov rdx, op3Len
    syscall
    ret

goAgain:
    mov rax, 1
    mov rdi, 1
    mov rsi, confirm
    mov rdx, cLen
    syscall
    
    mov rax, 0
    mov rdi, 0
    mov rsi, again
    mov rdx, 0xff
    syscall
    
    cmp byte [again], 0x79
    je _start
    cmp byte [again], 0x59
    je _start
    jmp doneIf

doneIf:
    mov rax, 60
    mov rdi, 0
    syscall