Explanation of SBB instruction

Question

I have this Asm from a book that suppose to do a Boolean cast: rax := rax ? 1 : 0

1. neg      rax
2. sbb      rax,rax
3. neg      rax

But as i understand this code and the instructions (below), this would work only if the register will have 0 in it.

because lets assume that (register have some positive number in it):

rax = 9    ;initial register
rax = -9   ;after line 1
rax = -17  ;after line 2
rax = 17   ;after line 3

register have 0 in it:

rax = 0    ;initial register
rax = 0    ;after line 1
rax = 0    ;after line 2
rax = 0    ;after line 3

I think that the author meant to do add in line 2 instead of sbb am i correct?

Instruction explanations: neg instruction:

neg Destination      ;Destination = -Destination      
if(Destination == 0)
  CF = 0;
else 
  CF = 1;

sbb instruction:

sbb Destination, Source      ;Destination = Destination - (Source + CF);

Answer 1

SBB:

Destination = Destination - (Source + CF);

-9 - ( -9 + 1 ) = -9 - ( -8 ) = -9 + 8 = -1, not -17