Exception/Error handling in NASM assembly

问题:

How do I handle errors in NASM assembly? For example I have this code to read user Input:

mov eax,3
mov ebx,0
mov ecx,Buffer
mov edx,BUFFERLENGTH
int 80H

If for some reason this system call cannot be executed, I'd like to have the program jump to a label that prints "An error has occured" or something like that. How do I do that?

Also, is it possible to get the name of the exception or error code?

Thanks

回答1:

After the kernel call, EAX is going to have two possibilites;

• Number of characters entered.

• Negated error code.

              int     80H
              or      eax, eax
              jns     OK        ; Tests sign flag
  
              neg     eax       ; Converts error code to positive value
      ;   Error trapping here
  
         OK:  dec     eax       ; Bump by one cause length includes CR
              jnz     Good
      ; Do something special if operator only entered CR
  
       Good:  nop
  

  This is an example how you could evaluate if there is an error and if operator even entered anything.