Linux Kernel Module Cheat

userland/arch/x86_64/bt.S: BT

Bit test: test if the Nth bit a bit of a register is set and store the result in the CF FLAG.
```
CF = reg[N]
```
userland/arch/x86_64/btr.S: BTR

Do a BT and then set the bit to 0.
userland/arch/x86_64/btc.S: BTC

Do a BT and then swap the value of the tested bit.
userland/arch/x86_64/setcc.S: SETcc

Set a byte of a register to 0 or 1 depending on the cc condition.

Bibliography: https://stackoverflow.com/questions/1406783/how-to-read-and-write-x86-flags-registers-directly/30952577#30952577
userland/arch/x86_64/popcnt.S: POPCNT

Count the number of 1 bits.
userland/arch/x86_64/test.S: TEST

Like CMP but does AND instead of SUB:
```
ZF = (!(X && Y)) ? 1 : 0
```