Computer Hardware User's Guide

2-cycle store
The read of
src
2 cannot start
until the store is complete
2-cycle read of
src
1 and
src
2
Clocking Memory Accesses
8-28
Example 8–18. Operand Swapping Alternative
Switch the operands of the 3-operand instruction so that the internal read is
performed first.
STI R0,*AR6 ; AR6 points to MSTRB space
ADDI3 *AR3,*AR1,R0 ; AR3 points to on-chip RAM (
src
2)
; AR1 points to MSTRB space (
src
1)
H1
H3
Pipeline Operation
PC Fetch
Decode Read Execute
n STI
n+1 ADDI3 STI
n+2 ADDI3 STI
n+3 STI
n+4 ——
n+5 ADDI3
n+6 ——
n+7 ADDI3
n+8 ADDI3