Hacker's Delight

2-12. Overflow Detection

“Overflow” means that the result of an arithmetic operation is too large or too small to be correctly represented in the target register. This section discusses methods that a programmer might use to detect when overflow has occurred, without using the machine’s “status bits” that are often supplied expressly for this purpose. This is important because some machines do not have such status bits (e.g., MIPS), and because even if the machine is so equipped, it is often difficult or impossible to access the bits from a high-level language.

Signed Add/Subtract

When overflow occurs on integer addition and subtraction, contemporary machines invariably discard the high-order bit of the result and store the low-order bits that ...