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我有一段時間做作業，很喜歡一些指導。該任務要求您將任何基數的ASCII字符串轉換爲任意基數。當我調用AsciiToDigit過程（嵌套在ReadInteger過程中）時，程序掛起，我找不到原因。調試器沒有任何幫助，因爲它不會執行任何操作，而只會在程序的該部分掛起。x86將ASCII字符轉換爲數字
我相當肯定我需要將字符轉換爲數字先做正確的，但也許我失去了一些東西。感謝任何人都可以提供的幫助。
TITLE MASM Template (main.asm)
; Description:
;
; Revision date:
INCLUDE Irvine32.inc
.data
basePrompt BYTE "What base (2-16 or 0 to quit): ",0
numPrompt BYTE "Number please: ",0
invalid BYTE "Invalid base, please try again.",0
base2 BYTE "Base 2: ",0
base8 BYTE "Base 8: ",0
base10 BYTE "Base 10: ",0
base16 BYTE "Base 16: ",0
base DWORD 0
.code
main PROC
call Clrscr
State0: ; initial state to accept base number
mov edx, OFFSET basePrompt
call ReadBase
cmp al, '0' ; check if 0 entered
je ProgEnd ; jump to ProgEnd if 0 entered
mov base, ebx
mov edx, OFFSET numPrompt
call WriteString
call ReadInteger
mov ebx, 2
mov edx, OFFSET base2
call WriteString
call WriteInteger
mov ebx, 8
mov edx, OFFSET base8
call WriteString
call WriteInteger
mov ebx, 10
mov edx, OFFSET base10
call WriteString
call WriteInteger
mov ebx, 16
mov edx, OFFSET base16
call WriteString
call WriteInteger
call Crlf
jmp State0 ; jump back to beginning of program
ProgEnd: ; jump point to end of programt
exit
main ENDP
;-----------------------------------------------------
ReadInteger PROC
;
; ReadInteger is passed one argument in bl representing the base of the number to be input.
; Receives: bl register
; Returns: EAX
;-----------------------------------------------------
nextChar:
call ReadChar ; Get the next keypress
call WriteChar ; repeat keypress
call AsciiToDigit
shl ebx,1 ; shift to make room for new bit
or ebx,eax ; set the bit to eax
cmp al, 13 ; check for enter key
jne nextChar
ret
ReadInteger ENDP
;-----------------------------------------------------
WriteInteger PROC
;
; Will display a value in a specified base
; Receives: EAX register (integer), bl (base)
; Returns: nothing
;-----------------------------------------------------
mov ecx, 0 ;count the digits
nextDigit:
mov edx, 0 ;prepare unsigned for divide
div ebx
push edx ;remainder will be in dl
inc ecx ;count it!
cmp eax,0 ;done when eax becomes 0
jne nextDigit
;now the digits are on the stack
;pop them off and convert to ASCII for output
outDigit:
pop eax ;digits come off left to right
add eax, '30' ;add 0011 to front to get ASCII
call WriteChar
loop outDigit
call Crlf
ret
ret
WriteInteger ENDP
;-----------------------------------------------------
ReadBase PROC
;
; Prompts the user for input and stores input into EAX.
; Receives: EDX register
; Returns: EAX
;-----------------------------------------------------
Call WriteString
xor ebx, ebx ; clear ebx
call ReadChar
call WriteChar
cmp al, '0'
je Done
cmp al, 13 ; look for return carriage, jump to end
je Done
mov ebx, eax
shl ebx, 1 ; shift ebx left one
call ReadChar
call WriteChar
or ebx, eax
Done:
call Crlf
ret
ReadBase ENDP
;-----------------------------------------------------
AsciiToDigit PROC
;
; This procedure receives the ASCII code of a digit and returns the numerical digit value.
; Receives: EAX register
; Returns: EAX
;-----------------------------------------------------
cmp eax, 61h
jb Upper
sub eax,61h
jmp done
Upper:
cmp eax, 41h
jb Digit
sub eax, 41h
jmp done
Digit:
sub eax,30h
done:
ret
AsciiToDigit ENDP
;-----------------------------------------------------
DigitToAscii PROC
;
; This procedure receives digit and returns Ascii value
; Receives: EAX register
; Returns: EAX
;-----------------------------------------------------
add eax, 30h
ret
DigitToAscii ENDP
END main
將'add eax，30h'改爲'add eax'，'0''會改善代碼的可讀性。另外，也許'add eax'，'30'應該是'add eax'，'0''。 – AusCBloke 2012-02-25 03:05:21
謝謝你非常好。儘管如此。 – 2012-02-25 03:14:34
ReadChar是否將結果返回給EAX？ WriteChar保存EAX嗎？ AsciiToDigit顯然期望EAX中的結果，因此請檢查該假設。如果你的調試器沒有幫助，刪除線路直到它工作。刪除WriteChar。將ReadChar替換爲EAX的簡單賦值（假設您調用該函數並獲得了很好的輸入）。跳過對AsciiToDigit的呼叫。修剪你的程序，直到它工作。此外，你應該記錄「爲什麼」，而不是「什麼」。像「shift ebx left one」這樣的評論是無用的，因爲它清楚'shl ebx，1'的作用。但是*爲什麼*你將ebx左移1？ – indiv 2012-02-25 05:17:39