#include <stdio.h>

int pack(int field, int index, int value);
int unpack(int field, int index);

int main(void) {

	int bit = 0;

	bit = pack(bit, 0, 1);
	bit = pack(bit, 1, 0);
	bit = pack(bit, 2, 1);

	printf("bit: %i, index 0: %i, index 1: %i, index 2: %i", bit, unpack(bit, 0), unpack(bit, 1), unpack(bit, 2));
	return 0;

}

int pack(int field, int index, int value) {

	return field|value<<index;

}

int unpack(int field, int index) {

	int mask = 1 << index;
	int value = field & mask;

	value = value >> index;

	return value;

}