> Instead of testing the sign bit, the low-level system call should
> probably do something like this:
>
> ... do system call, return in %eax ...
> movl %eax,%edx
> addl $4095,%edx
> jc error error if return was -1 .. -4095
If you're only testing the carry flag with the "jc" instruction and
not using it later, use this instead. Remember "jae" is unsigned, and
-4095 is a huge unsigned number:
cmpl $-4095,%eax
jae error
Or in C:
if ((unsigned) eax >= (unsigned)-4095) {
goto error;
}
Tom.