Partitioned branch condition resolution logic

This paper presents the design of an early condition resolution circuit. The proposed circuit works in parallel with the arithmetic unit, and calculates the Equal to (EQ), Greater-than (GT), Less-than (LT), Overflow (OV), Underflow (UF), and Carry-out (C/sub out/), conditions. The proposed logic is reconfigurable, and can calculate all the conditions (mentioned above) for one 64-bit, two 32-bit, four 16-bit, or eight 8-bit signed and unsigned operands. The reconfigurability of the logic is achieved using only four control signals. Two of the control signals (Part O, Part 1) are used to partition the logic into 64, 32, 16, or 8-bit independent condition resolvers and the Sign control signal is used to control the signed/unsigned operation. The Add-Sub control signal specifies and controls the Add/Subtract operation for the condition resolution. In order to achieve high speed with reconfigurability and minimum area, new techniques are developed for calculating the conditions before the results are available. The proposed logic is designed for VLIW or Media processors, which require a high degree of reconfigurability, and high speed operation. It can also be used in MIPS family of processors for early branch condition resolution, to avoid branch stalls. Simulations of realizations in a standard digital CMOS fabrication technology show a 30% improvement in speed and a 25% savings in area using the approaches presented here.