; Get a hard copy on Amazon for $10.

[0x18]
dec [xchg rax,rax] inc
rdtsc
shl      rdx,0x20
or       rax,rdx
mov      rcx,rax

rdtsc
shl      rdx,0x20
or       rax,rdx

cmp      rcx,rax
; xorpd(&)xorpd.net