2-cycle store
The read of
src2 cannot start
until the store is complete
2-cycle read of
src1 and src2
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 (
src2)
; AR1 points to MSTRB space (
src1)
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