2-cycle dummy
load of
src
2
R0, *AR6 until the
store is complete
actual read of
src
2 and
src
1
Clocking Memory Accesses
8-27
Pipeline Operation
Example 8–17. Dummy sr2 Read

STI R0,*AR6 ; AR6 points to MSTRB space

ADDI3 *AR1,*AR3,R0 ; AR3 points to on-chip RAM (

src

1)

; AR1 points to MSTRB space (

src

2)

H1
H3
Pipeline Operation
PC Fetch Decode Read Execute
nSTI
n+1 ADDI3 STI
n+2 ADDI3 STI
n+3 — STI
n+4 ——
n+5 ADDI3 —
n+6 ——
n+7 ADDI3 —
n+8 ADDI3

Two cycles are required for the MSTRB store. Two additional cycles are required

for the dummy MSTRB read of *AR3 (because a read follows a write). One cycle

is required for an actual MSTRB read of *AR3.