jump destination too far : by 3 byte(s)

问题:

I m having a problem with my loop, the code contained in it is long and it gives me error jump destination too far : by 3 byte(s). When ı remove:

mov edx,offset str1 
call writestring

this part below the main PROC, it doesnt give an error. But ı need this string user enters a negative number to give a message. How can ı?

INCLUDE Irvine32.inc

.data

    money      dword    200,100,50,20,10,5,1
    str1       byte     "Enter the amounts for each value of money : ",0
    str2       byte     "The sum of your moneys are:",0
    total      dword    0
    buffer     dword    1000 dup(0),0    
    str3       byte     "Do not enter neg number ",0

.code
main PROC
    mov edx,offset str1 
    call writestring
    call crlf
    mov ecx,lengthof money
    mov esi,0
    mov edi,0

start1:
    jmp continue
    don:
    push ecx


    mov edx,ecx
    mov edx,0

    mov edx,7
    sub edx,ecx
    mov ecx,edx
    mov edi,0
    mov esi,0
        start2:

            mov eax,money[esi]
            call writedec
            mov ebx,eax
            mov al,'x'
            call writechar
            mov eax,buffer[edi]
            call writedec
            call crlf
            add esi,4 
            add edi,4

        loop start2

    pop ecx
    continue:

    ;**************************************************
    mov edx,0
    mov eax,money[esi]
    call writedec
    mov ebx,eax
    mov al,'x'
    call writechar
    call readint
    ;***************************************************

    sub eax,0
    js don
    mov buffer[edi],eax
    ;*************************
    mul ebx
    add total,eax       ;we add each the multiplication to total.
    add esi,4           ;increases the index by 4.(because of dword type)
    add edi,4


loop start1

    mov edx,offset str2
    call writestring
    mov eax, total
    call writedec

    exit
main ENDP
END main

回答1:

loop has limited range. It can only jump up to 127 bytes ahead or 128 back in the instruction stream measured from the start of the following instruction.

To get around that, you can do something like the following.

Instead of

label1:

<lots of code>

loop label1 

if the label is out of reach you can do something like this:

label1:

<lots of code>

loop tmp1
jmp tmp2
tmp1:
  jmp label1
tmp2:

or else use a different construct based on conditional jumps that don't have the range limitation.