请对DES算法熟悉的高手讲解一下以下代码的含义
pdp 2006-04-10 02:00:14 以下代码是DES中IP盒子置换代码
/* Initial permutation IP */
t = ((leftt >> 4) ^ right) & 0x0f0f0f0fL;
right ^= t;
leftt ^= (t << 4);
t = ((leftt >> 16) ^ right) & 0x0000ffffL;
right ^= t;
leftt ^= (t << 16);
t = ((right >> 2) ^ leftt) & 0x33333333L;
leftt ^= t;
right ^= (t << 2);
t = ((right >> 8) ^ leftt) & 0x00ff00ffL;
leftt ^= t;
right ^= (t << 8);
leftt = ((leftt >> 1) | (leftt << 31));
t = (leftt ^ right) & 0x55555555L;
leftt ^= t;
right ^= t;
right = ((right >> 1) | (right << 31));
我看了很久也没看明白,请熟悉这段代码的高手讲解一下