int bit fields

#include <iostream>
#include <iomanip>

using namespace std;

typedef union _test {
    unsigned int h;
    struct {
        unsigned int f : 1, e : 8, m : 23;
    } s;
} test;

template <typename T>
void dump_hex(const T * ptr) {
    unsigned char * z = reinterpret_cast<unsigned char*>(const_cast<T*>(ptr));

    for (size_t i = 0; i < sizeof(T); ++i) {
        if (i != 0) cout << " ";
                cout << "0x" << hex << (z[i] >> 4) << (z[i] & 0x0F);
    }
}

template <typename T>
void dump_bin(const T & val, unsigned int len = 8 * sizeof(T)) {
    unsigned long long x = val;

    for (unsigned int i = 0; i < len; ++i) {
        cout << (x & 1);
        x >>= 1;
    }
}

void dump(const test & val) {
        cout << "0x" << setw(8) << setfill('0') << hex << val.h << endl;

        dump_hex(&val); cout << endl;

        dump_bin(val.s.f, 1);  cout << " ";
        dump_bin(val.s.e, 8);  cout << " ";
    dump_bin(val.s.m, 23); cout << endl;

    cout << endl;
}

int main()
{
    test z;

    z.h = 0;
    z.s.f = 1;
    dump(z);
    /*
     * output:
     * 0x00000001
     * 0x01 0x00 0x00 0x00
     * 1 00000000 00000000000000000000000
     */

    z.h = 0;
    z.s.e = 255;
    dump(z);
    /*
     * output:
     * 0x000001fe
     * 0xfe 0x01 0x00 0x00
     * 0 11111111 00000000000000000000000
     */

    z.h = 0x12345678;
    dump(z);
    /*
     * output:
     * 0x12345678
     * 0x78 0x56 0x34 0x12
     * 0 00111100 11010100010110001001000
     */

    return 0;
}