C:\test\C>bufswap 536870855 268435399 2      ### 2^28+prime prime
size:536870855 offset;268435399
[         0          1 ...  268435397    268435398 ^  268435399    268435400   ...  536870853  536870854 ]
[ 268435399  268435400 ...  536870853    536870854 ^          0            1   ...  268435397  268435398 ]
iterative: swaps:536870855 took 23.912365889 secs.

[         0          1 ...  268435397    268435398 ^  268435399    268435400   ...  536870853  536870854 ]
[ 268435399  268435400 ...  536870853    536870854 ^          0            1   ...  268435397  268435398 ]
recursive: swaps:536870854 took 3.633964430 secs.