Pipeline Execution of Instruction Types
4-17
Pipeline
SPRU733
4.2.2 16
y
16-Bit Multiply Instructions
The 16
×
16-bit multiply instructions use both the E1 and E2 phases of the
pipeline to complete their operations (see Table 4
−
4). Figure 4
−
10 shows the
fetch, decode, and execute phases of the pipeline that the multiply instructions
use.
Figure 4
−
11 shows the operations occurring in the pipeline for a multiply. In the
E1 phase, the operands are read and the multiply begins. In the E2 phase, the
multiply finishes, and the result is written to the destination register. Multiply
instructions have one delay slot.
Table 4
−
4. 16
16-Bit Multiply Instruction Execution
Pipeline Stage
E1
E2
Read
src1
src2
Written
dst
Unit in use
.M
Figure 4
−
10. Multiply Instruction Phases
PG
PS
PW
PR
DP
DC
E1
E2
1 delay slot
Figure 4
−
11.Multiply Instruction Execution Block Diagram
(data)
Operands
ÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁ
Register file
Write results
ÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
ÁÁÁÁÁ
Functional
unit
.M
E1
E2