這個位操作函數做什麼？

Question

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; 
} 

Answer 1

OR和SHIFT語句在最高有效位（最多32位）的右側填充了x的所有位。連同前遞減和遞增後的語句，這個函數計算（作爲函數名稱suggets）下一個冪次數，等於或大於給定數字（如果x大於0且小於2^32 ）

Answer 2

此功能x舍高達2下一個最高權力這正是代碼中here

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++;