Barrel Shifter for Byte, Word and Double-Word Operands and Barrel Shifter Control Setup for Multifunction and Performance
Original Publication Date: 1988-May-01
Included in the Prior Art Database: 2005-Feb-15
This article describes a multifunction, multiple-bit (byte, word or double word) shifter device with minimum hardware for fast processor shift operations and a technique to control it. The control may be directly from a microword or from a register which was set dependent on the processor instruction to be executed and/or a count register containing the shift amount. A barrel shift function for 8-, 16-, or 32-bit operands and providing for shift right logical, shift right arithmetic, shift left circular and shift left logical operations in complementary metal-oxide semiconductor (CMOS) logic technology is provided in a 16-bit processor. Correct arithmetic indicator settings are also provided for each of the processor shift operations.