Special masking operation in c++

Question

I need to xor the every single bits each other in a variable using c++ Let's consider 4-bit values a and x where their bit-representation is a = a3a2a1a0 and x = x3x2x1x0. We dene the masking operation "." as a.x = a3x3(xor)a2x2(xor)a1x1(xor)a0x0.

I did a&x and find a3x3 a2x2 a1x1 a0x0 now i need to xor them but how ? is there any special way to do that ? like '&' operation ? I searched but didn't find anything..any help will be appreciated!

Answer 1

You'll need to shift "a and x" to do the xor of all bits.

Something like:

uint32_t a = 0xa;
uint32_t x = 0xb;

uint32_t tmp = a & x;         // Bitwise AND of a and x
uint32_t res = 0;
for (int i = 0; i < 32; ++i)
{
    res = res ^ (0x1 & tmp);  // Only include LSB of tmp in the XOR
    tmp = tmp >> 1;           // Shift tmp to get a new LSB
}
cout << "Result: " << res << endl;

An alternative solution could be:

uint32_t a = 0xa;
uint32_t x = 0xb;

uint32_t tmp = a & x;         // Bitwise AND of a and x
uint32_t res = 0;
while (tmp > 0)
{
    if ((tmp % 2) == 1) res = (res + 1) & 0x1;  // XOR operation
    tmp = tmp/2;                                // Shift operation
}
cout << "Result: " << res << endl;