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--- chess:programming:bit_operations [2021/11/03 11:46] – peter
+++ chess:programming:bit_operations [2021/11/05 09:55] (current) – peter
@@ Line 9: / Line 9: @@
 |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:
+<code>
+00000000101111000110000101001110   &    (n)
+10101010101010101010101010101010        (0xAAAAAAAA)
+————————————————————————————————
+00000000101010000010000000001010        (Contains all even bits)
+</code>
+Apply an odd mask against it:
+<code>
+00101101011001010111000110001001   &    (n)
+01010101010101010101010101010101        (0x55555555)
+————————————————————————————————
+00000000000101000100000101000100        (Contains all odd bits)
+</code>
+<WRAP info>
+**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
+</WRAP>
+----