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///
/// @file floorPow2.cpp
/// @brief Round down to nearest power of 2.
///
/// Copyright (C) 2022 Kim Walisch, <kim.walisch@gmail.com>
///
/// This file is distributed under the BSD License. See the COPYING
/// file in the top level directory.
///
#include <primesieve/pmath.hpp>
#include <stdint.h>
#include <iostream>
#include <cmath>
#include <cstdlib>
void check(bool OK)
{
std::cout << " " << (OK ? "OK" : "ERROR") << "\n";
if (!OK)
std::exit(1);
}
uint64_t floorPow2_cmath(uint64_t n)
{
return 1ull << (uint64_t) std::log2(n);
}
int main()
{
uint64_t n;
uint64_t res1;
uint64_t res2;
for (n = 1; n < 100000; n++)
{
res1 = floorPow2(n);
res2 = floorPow2_cmath(n);
std::cout << "floorPow2(" << n << ") = " << res1;
check(res1 == res2);
}
n = (1ull << 32) - 1;
res1 = floorPow2(n);
res2 = floorPow2_cmath(n);
std::cout << "floorPow2(" << n << ") = " << res1;
check(res1 == res2);
n = 1ull << 32;
res1 = floorPow2(n);
res2 = floorPow2_cmath(n);
std::cout << "floorPow2(" << n << ") = " << res1;
check(res1 == res2);
n = (1ull << 63) - 1;
res1 = floorPow2(n);
std::cout << "floorPow2(" << n << ") = " << res1;
check(res1 == (1ull << 62));
n = 1ull << 63;
res1 = floorPow2(n);
std::cout << "floorPow2(" << n << ") = " << res1;
check(res1 == (1ull << 63));
n = 18446744073709551615ull;
res1 = floorPow2(n);
std::cout << "floorPow2(" << n << ") = " << res1;
check(res1 == (1ull << 63));
std::cout << std::endl;
std::cout << "All tests passed successfully!" << std::endl;
return 0;
}
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