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#include <terraces/definitions.hpp>
#ifdef _WIN64
#pragma intrinsic(_BitScanForward64, _BitScanReverse64, __popcnt64)
#else
#pragma intrinsic(_BitScanForward, _BitScanReverse, __popcnt)
#endif
namespace terraces {
namespace bits {
#ifdef _WIN64
inline index popcount(index word) { return (index)__popcnt64(word); }
inline index bitscan(index word) {
unsigned long idx;
_BitScanForward64(&idx, word);
return (index)idx;
}
inline index rbitscan(index word) {
unsigned long idx;
_BitScanReverse64(&idx, word);
return (index)idx;
}
#else
inline index popcount(index word) { return index(__popcnt(word)); }
inline index bitscan(index word) {
unsigned long idx;
_BitScanForward(&idx, word);
return index(idx);
}
inline index rbitscan(index word) {
unsigned long idx;
_BitScanReverse(&idx, word);
return index(idx);
}
#endif
namespace {
constexpr index max_index = std::numeric_limits<index>::max();
}
inline bool add_overflow(index a, index b, index& result) {
result = a + b;
if (max_index - b < a) {
return true;
} else {
return false;
}
}
inline bool mul_overflow(index a, index b, index& result) {
result = a * b;
if (max_index / b < a) {
return true;
} else {
return false;
}
}
} // namespace bits
} // namespace terraces
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