C:\test\C>bufswap 30000000 20000000 2
size:30000000 offset;20000000
[         0          1 ...   19999998     19999999 ^   20000000     20000001   ...   29999998   29999999 ]
[  20000000   20000001 ...   29999998     29999999 ^          0            1   ...   19999998   19999999 ]
iterative: swaps:30000000 took 0.235516729 secs.

[         0          1 ...   19999998     19999999 ^   20000000     20000001   ...   29999998   29999999 ]
[  20000000   20000001 ...   29999998     29999999 ^          0            1   ...   19999998   19999999 ]
recursive: swaps:20000000 took 0.163142653 secs.