2-cycle dummy
load of
src2
R0, *AR6 until the
store is complete
actual read of
src2 and src1
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 (
src1)
; AR1 points to MSTRB space (
src2)
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
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.