; Get a hard copy on Amazon for $10.

[0x2f]
dec [xchg rax,rax] inc 
    xor      eax,eax
.loop:
    jrcxz    .exit_loop
    inc      rax
    mov      rdx,rcx
    dec      rdx
    and      rcx,rdx
    jmp      .loop
.exit_loop:
; xorpd(&)xorpd.net