Chess - Programming - Bit Operations

Expression	Description	Example
x & y	AND the bits of x with those of y	21 & 7 = 10101 & 00111 = 00101 = 5
x \| y	OR the bits of x with those of y	21 \| 7 = 10101 \| 00111 = 10111 = 23
x ^ y	XOR the bits of x with those of y	21 ^ 7 = 10101 ^ 00111 = 10010 = 18
~x	Inverting (complementing) the bits of x (0 → 1 and 1 → 0)	~7 = 11111111111111000 = 65528
x « y	Shift the bits of x to the left y positions	25 « 3 = 10101 « 3 = 10101000 = 168
x » y	Shift the bits of x to the right y positions	25 » 3 = 10101 » 3 = 00010 = 2

Get only even or odd bits

Take a number, say 12345678.

In Binary, this is 00000000101111000110000101001110.

Apply an even mask against it:

00000000101111000110000101001110   &    (n)
10101010101010101010101010101010        (0xAAAAAAAA)
————————————————————————————————
00000000101010000010000000001010        (Contains all even bits)

Apply an odd mask against it:

00101101011001010111000110001001   &    (n)
01010101010101010101010101010101        (0x55555555)
————————————————————————————————
00000000000101000100000101000100        (Contains all odd bits)

NOTE: Use Masks.

Mask 0xAAAAAAAA has all its even bits set.
- Its bitwise AND with a number will separate out the even bits.
- 1010 1010 1010 1010 1010 1010 1010 1010

Mask 0x55555555 has all its odd bits set.
- Its bitwise AND with a number will separate out the odd bits.
- 1010 1010 1010 1010 1010 1010 1010 1010