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Add c++20 version of CountBits #80

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Merged
sipa merged 1 commit into from
Apr 11, 2024
Merged

Add c++20 version of CountBits #80

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10 changes: 8 additions & 2 deletions src/int_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,9 @@
#include <algorithm>
#include <type_traits>

#ifdef _MSC_VER
#if defined(__cpp_lib_int_pow2) && __cpp_lib_int_pow2 >= 202002L
# include <bit>
#elif defined(_MSC_VER)
# include <intrin.h>
#endif

Expand Down Expand Up @@ -142,7 +144,11 @@ constexpr inline I Mask() { return ((I((I(-1)) << (std::numeric_limits<I>::digit
/** Compute the smallest power of two that is larger than val. */
template<typename I>
static inline int CountBits(I val, int max) {
#ifdef _MSC_VER
#if defined(__cpp_lib_int_pow2) && __cpp_lib_int_pow2 >= 202002L
// c++20 impl
(void)max;
return std::bit_width(val);
#elif defined(_MSC_VER)
(void)max;
unsigned long index;
unsigned char ret;
Expand Down