Given a 32-bit integer, we want to find out the next highest power of 2. For example, the next power of two for 127 is 128. We can use the following C Macro:
1 2 3 4 5 6 7 8 9 | #define next_power_of_two(x) \ ({ unsigned int vv = x; \ vv--; \ vv |= vv >> 1; \ vv |= vv >> 2; \ vv |= vv >> 4; \ vv |= vv >> 8; \ vv |= vv >> 16; \ ++vv; }) |
#define next_power_of_two(x) \
({ unsigned int vv = x; \
vv--; \
vv |= vv >> 1; \
vv |= vv >> 2; \
vv |= vv >> 4; \
vv |= vv >> 8; \
vv |= vv >> 16; \
++vv; })We can also use the following C/C++ function to compute the next power of two. If the given integer it is already the power of two, it will simply return it.
1 2 3 4 5 6 7 8 9 10 11 12 | inline unsigned int next_power_of_two(int x) { unsigned int v = x; v--; v |= v >> 1; v |= v >> 2; v |= v >> 4; v |= v >> 8; v |= v >> 16; ++v; return v; } |
inline unsigned int
next_power_of_two(int x) {
unsigned int v = x;
v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
++v;
return v;
}–EOF (The Ultimate Computing & Technology Blog) —
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