reorganize dir

Signed-off-by: Mia Steinkirch <mia.steinkirch@gmail.com>

ebook_src/bitwise/swap_odd_even.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+''' Swap odd and even bits in a smart way in a binary:
+    1) first for odds, take n and move the odd:
+        (a) Mask all odd bits with 10101010 (0xAA)
+        (b) shift by right by 1
+    2) do the same to ints with 01010101
+    3) merge
+'''
+
+
+
+def swap_odd_even(num):
+    '''
+    >>> num = 0b11011101
+    >>> result = '0b1101110'
+    >>> swap_odd_even(num) == result
+    True
+    '''
+
+    mask_odd = 0xAA # 0b10101010
+    mask_even = 0x55 # 0b1010101
+    odd = num & mask_odd
+    odd >>= 1
+    even = num & mask_even
+    even >>= 1
+    return bin(odd | even)
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+