 Carry flag

A processor status bit recording arithmetic carry. For unsigned addition of $n$-bit inputs, $X+Y=Z+2^{n}C$, where $Z$ is the stored result. In the ARM architecture family, subtraction instead uses $X-Y=Z-2^n(1-C)$, so a set arithmetic carry means no borrow. This convention must be checked for the target instruction set; it is not a signed-overflow test.