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#ifdef _MSC_VER
#include <intrin.h>
#pragma intrinsic(_umul128)
#endif
#include <cstring>
#include "common/uint128.h"
namespace Common {
u128 Multiply64Into128(u64 a, u64 b) {
u128 result;
#ifdef _MSC_VER
result[0] = _umul128(a, b, &result[1]);
#else
unsigned __int128 tmp = a;
tmp *= b;
std::memcpy(&result, &tmp, sizeof(u128));
#endif
return result;
}
std::pair<u64, u64> Divide128On32(u128 dividend, u32 divisor) {
u64 remainder = dividend[0] % divisor;
u64 accum = dividend[0] / divisor;
if (dividend[1] == 0)
return {accum, remainder};
// We ignore dividend[1] / divisor as that overflows
const u64 first_segment = (dividend[1] % divisor) << 32;
accum += (first_segment / divisor) << 32;
const u64 second_segment = (first_segment % divisor) << 32;
accum += (second_segment / divisor);
remainder += second_segment % divisor;
if (remainder >= divisor) {
accum++;
remainder -= divisor;
}
return {accum, remainder};
}
} // namespace Common
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