What does this bit-manipulating function do?

unsigned long ccNextPOT(unsigned long x){

x = x - 1;
x = x | (x >> 1);
x = x | (x >> 2);
x = x | (x >> 4);
x = x | (x >> 8);
x = x | (x >>16);
return x + 1;
}

shareimprove this question

edited Dec 26 '11 at 16:42 Ondrej Tucny 13.8k22450

asked Dec 26 '11 at 15:45 guoxx 1007

x

x

shareimprove this answer

answered Dec 26 '11 at 16:54 leonbloy 30.5k66491

unsigned int v; // compute the next highest power of 2 of 32-bit v

v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++;

shareimprove this answer

edited Aug 1 '13 at 8:08

answered Jul 31 '13 at 13:45 Lưu Vĩnh Phúc 4,75831332