SRISC4 CPU

SRISC4 Datapath

Shifter Operations

controloperation
000shift left logical
001shift right logical
011shift right arithmetic
100rotate left
101rotate right

control[0]: right vs. left
control[1]: arithmetic vs. logical
control[2]: rotate vs. shift

Shift Instructions

shiftdirRegisterImmediate
logicalleftsllslli
logicalrightsrlsrli
arithmeticrightsrasrai
rotateleftrolroli
rotaterightrorrori

pseudo-instruction

sll
rC ← rA << (rB[4:0])
slli
rC ← rA << (sh)

rB is zero for slli

Data Output Control Signals (version 1)

control[4:0]operation
00xxxALU operations
10xxxshift
11xxxshift - immediate

control[4:3] is part of the data multiplexer control


Maintained by John Loomis, last updated 22 October 2008