mirror of
https://github.com/AquariaOSE/Aquaria.git
synced 2024-12-25 14:15:46 +00:00
85 lines
1.2 KiB
C
85 lines
1.2 KiB
C
|
#ifndef BITHACKS_H
|
||
|
#define BITHACKS_H
|
||
|
|
||
|
#ifdef _MSC_VER
|
||
|
# include <intrin.h>
|
||
|
#endif
|
||
|
|
||
|
namespace bithacks {
|
||
|
|
||
|
typedef unsigned int uint32;
|
||
|
typedef int int32;
|
||
|
|
||
|
// floor to next power of 2
|
||
|
inline uint32 flp2(uint32 x)
|
||
|
{
|
||
|
x |= (x >> 1);
|
||
|
x |= (x >> 2);
|
||
|
x |= (x >> 4);
|
||
|
x |= (x >> 8);
|
||
|
x |= (x >> 16);
|
||
|
return x - (x >> 1);
|
||
|
}
|
||
|
|
||
|
// ceil to next power of 2
|
||
|
inline uint32 clp2(uint32 x)
|
||
|
{
|
||
|
--x;
|
||
|
x |= (x >> 1);
|
||
|
x |= (x >> 2);
|
||
|
x |= (x >> 4);
|
||
|
x |= (x >> 8);
|
||
|
x |= (x >> 16);
|
||
|
return x + 1;
|
||
|
}
|
||
|
|
||
|
inline uint32 popcnt(uint32 x)
|
||
|
{
|
||
|
x -= ((x >> 1) & 0x55555555);
|
||
|
x = (((x >> 2) & 0x33333333) + (x & 0x33333333));
|
||
|
x = (((x >> 4) + x) & 0x0f0f0f0f);
|
||
|
x += (x >> 8);
|
||
|
x += (x >> 16);
|
||
|
return x & 0x0000003f;
|
||
|
}
|
||
|
|
||
|
inline uint32 ctz(uint32 x)
|
||
|
{
|
||
|
#ifdef __GNUC__
|
||
|
return __builtin_ctz(x);
|
||
|
#elif defined(_MSC_VER) && defined(_M_IX86)
|
||
|
unsigned long r = 0;
|
||
|
_BitScanForward(&r, x);
|
||
|
return r;
|
||
|
#else
|
||
|
return popcnt((x & -x) - 1);
|
||
|
#endif
|
||
|
}
|
||
|
|
||
|
inline unsigned int clz(uint32 x)
|
||
|
{
|
||
|
#ifdef __GNUC__
|
||
|
return __builtin_clz(x);
|
||
|
#elif defined(_MSC_VER) && defined(_M_IX86)
|
||
|
unsigned long r = 0;
|
||
|
_BitScanReverse(&r, x);
|
||
|
return r;
|
||
|
#else
|
||
|
x |= (x >> 1);
|
||
|
x |= (x >> 2);
|
||
|
x |= (x >> 4);
|
||
|
x |= (x >> 8);
|
||
|
x |= (x >> 16);
|
||
|
return 32 - popcnt(x);
|
||
|
#endif
|
||
|
}
|
||
|
|
||
|
|
||
|
|
||
|
|
||
|
|
||
|
|
||
|
}; // end namespace bithacks
|
||
|
|
||
|
#endif
|