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