The design of a 64-bit integer multiplier/divider unit

Abstract

The highlights of the design of an integer multiplier/divider unit for a 64-b processor are presented. The final design is the result of a compromise between performance, complexity, and transistor count. It is optimized for two specific operations with the same hardware being shared by the remaining operations. Thus, for example, the multiplier can be configured for the execution of several different multiply operations and its hardware is also heavily utilized in division. The divider design is optimized for repetitive division by small numbers, since this is a characteristic of several important applications planned for the processor. For such small divisors, the reciprocal is calculated and stored in a content-addressable memory. The stored reciprocals can then be used to generate quotients through fast multiplication. Simulations of the planned applications show a 20% to 30% performance increase over alternative designs.<>