Assembly ADC (Add with carry) to C++

Question

There is an x86 assembly instruction ADC. I\'ve found this means "Add with carry". What does this mean/do? How would one implement the behavior of thi

Answer 1

There is a bug in this. Try this input:

unsigned first[10] =  {0x00000001};
unsigned second[10] = {0xffffffff, 0xffffffff};

The result should be {0, 0, 1, ...} but the result is {0, 0, 0, ...}

Changing this line:

carry = (first[i] > result[i]);

to this:

if (carry)
    carry = (first[i] >= result[i]);
else
    carry = (first[i] > result[i]);

fixes it.