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///
/// @file ilog2.cpp
/// @brief Test ilog2(x) function.
/// Note that the log2(x) function from <cmath> is not
/// accurate enough near 2^64.
///
/// Copyright (C) 2021 Kim Walisch, <kim.walisch@gmail.com>
///
/// This file is distributed under the BSD License. See the COPYING
/// file in the top level directory.
///
#include <imath.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);
}
int main()
{
uint64_t n;
uint64_t res1;
uint64_t res2;
for (n = 1; n < 100000; n++)
{
res1 = ilog2(n);
res2 = (uint64_t) std::log2(n);
std::cout << "ilog2(" << n << ") = " << res1;
check(res1 == res2);
}
n = (1ull << 32) - 1;
res1 = ilog2(n);
res2 = (uint64_t) std::log2(n);
std::cout << "ilog2(" << n << ") = " << res1;
check(res1 == (uint64_t) res2);
n = 1ull << 32;
res1 = ilog2(n);
res2 = (uint64_t) std::log2(n);
std::cout << "ilog2(" << n << ") = " << res1;
check(res1 == (uint64_t) res2);
n = (1ull << 63) - 1;
res1 = ilog2(n);
std::cout << "ilog2(" << n << ") = " << res1;
check(res1 == 62);
n = 1ull << 63;
res1 = ilog2(n);
std::cout << "ilog2(" << n << ") = " << res1;
check(res1 == 63);
n = 18446744073709551615ull;
res1 = ilog2(n);
std::cout << "ilog2(" << n << ") = " << res1;
check(res1 == 63);
std::cout << std::endl;
std::cout << "All tests passed successfully!" << std::endl;
return 0;
}
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