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#include <terraces/definitions.hpp>
#include <intrin.h>
#ifdef _WIN64
#pragma intrinsic(_BitScanForward64, _BitScanReverse64, __popcnt64)
#else
#pragma intrinsic(_BitScanForward, _BitScanReverse, __popcnt)
#endif
namespace terraces {
namespace bits {
#ifdef _WIN64
inline index_t popcount(index_t word) { return (index_t)__popcnt64(word); }
inline index_t bitscan(index_t word) {
unsigned long idx;
_BitScanForward64(&idx, word);
return (index_t)idx;
}
inline index_t rbitscan(index_t word) {
unsigned long idx;
_BitScanReverse64(&idx, word);
return (index_t)idx;
}
#else
inline index_t popcount(index_t word) { return index_t(__popcnt(word)); }
inline index_t bitscan(index_t word) {
unsigned long idx;
_BitScanForward(&idx, word);
return index_t(idx);
}
inline index_t rbitscan(index_t word) {
unsigned long idx;
_BitScanReverse(&idx, word);
return index_t(idx);
}
#endif
namespace {
constexpr index_t max_index = std::numeric_limits<index_t>::max();
}
inline bool add_overflow(index_t a, index_t b, index_t& result) {
result = a + b;
if (max_index - b < a) {
return true;
} else {
return false;
}
}
inline bool mul_overflow(index_t a, index_t b, index_t& result) {
result = a * b;
if (b != 0 && max_index / b < a) {
return true;
} else {
return false;
}
}
} // namespace bits
} // namespace terraces
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