#include <cassert>
#include <climits>
#include <cstdint>
#include <cstdio>

template <uint8_t d, typename int_type>
int_type get_matches_naive(int_type b)
{
    int_type ret = 0;
    for (size_t i = 0; i < sizeof(int_type); i++)
        if (((b >> i * CHAR_BIT) & 0xff) == d)
            ret |= (int_type)0x80 << i * CHAR_BIT;
    return ret;
}

template <uint8_t d, typename int_type>
int_type get_matches_bitwise(int_type b)
{
    // based on
    // https://g...content-available-to-author-only...d.edu/~seander/bithacks.html#HasLessInWord
    constexpr int_type mask_0x01 = (int_type)~0 / (int_type)0xff;
    constexpr int_type mask_0x7f = (int_type)0x7f * mask_0x01;
    constexpr int_type mask_0x80 = (int_type)0x80 * mask_0x01;
    constexpr int_type mask_d = d * mask_0x01;
    int_type matches_as_0x00 = mask_d ^ b;
    int_type matches_as_0x80 = (mask_0x80 - (matches_as_0x00 & mask_0x7f)) &
                               ~matches_as_0x00 & mask_0x80;
    return matches_as_0x80;
}

template <uint8_t d, typename int_type>
void test()
{
	int_type b = 0;
	do
	{
		assert((get_matches_naive<d, int_type>(b) ==
		        get_matches_bitwise<d, int_type>(b)));
	} while(--b != 0);
}

template <uint8_t d, typename int_type>
struct aux
{
	static void do_test()
	{
		test<d, int_type>();
		aux<d - 1, int_type>::do_test();
	}
};

template <typename int_type>
struct aux<0, int_type>
{
	static void do_test()
	{
		test<0, int_type>();
	}
};

int main()
{
	aux<0xff, uint16_t>::do_test();
	// TAKES TOO LONG FOR IDEONE
	//aux<0xff, uint32_t>::do_test();
	return 0;
}