: Example : // // Addition to 4-bit signed numbers.

// A carry out does not necessarily indicate overflow. // This implies that there can not be overflow when the signs of the numbers when the sign of the two operands are the same and the sign / Overflow Detection in Signed Addition // // There has been overflow in the addition of two n-bit two's complement // The digit over the 'C' is the carry out. // Addition of 4-bit unsigned representations of 10 and 7: if there is a carry out (from the MSB).

/ Overflow Detection in Unsigned Addition // // There is overflow in unsigned addition of two n-bit numbers The result might be too large or too small. / Overflow Definition // // Describes an arithmetic operation in which the result cannot / Binary Addition and Subtraction // :PH: 4.3 and classroom lectures. human reader and waste hardware and time unless the synthesisĪssign minus_i = 0 - i // No advantage over unary -.Īssign minus_i = ~i + 1 // No advantage over -.Īssign minus_i = i * -1 // Wastes hardware and time.Īssign minus_i = i / -1 // Wastes hardware and lots of time. ` ifdef NOT_THE_WAY_TO_DO_IT // The methods below work but they are slightly less clear to a compiler directive, similar to the C ' #define' pre-processor : Example : // // The module below negates its input. Example: 4-bit: Minimum -8, maximum 7. Example: 4-bit: Minimum 0, maximum 15. / Range of Representation: // // (Smallest and largest representable numbers.) / Example: Find 4-bit representation of -5. // Not surprisingly, the MSB is called the /sign bit/. // / Two's Complement Sign Bit // // A two's complement representation is negative if and only if the // Start with the n-bit binary representation of i. The /n-bit two's complement representation/ is usually understood to mean 'two's complement signed integer.' / Two's Complement Representation // // Since the use of two's complement is nearly universal, 'signed integer' // Keep this in mind for overflow and negative numbers. Computer integers do because they are represented by a fixed // Real-world integers don't have a maximum or minimum. Difference between real-world and computer integers: / Representation of Integers in Computers // :PH: 4.1, 4.2 / References // // :Q: Qualis, 'Verilog HDL Quick Reference Card Revision 1.0' // :H: Hyde, 'Handbook on Verilog HDL' // :PH: Patterson & Hennessy, 'Computer Organization & Design' Real-World Integer Adders (Under Construction) L05.v // / LSU EE 3755 - Fall 2012 - Computer Organization // // / Verilog Notes 5 - Integer Addition and Subtraction // Time-stamp: // / Contents // // Representation of Integers in Computers

Verilog wire signed