SMJ320C80 Datasheet, PDF (46/157 Pages) Texas Instruments – DIGITAL SIGNAL PROCESSOR

SMJ320C80
DIGITAL SIGNAL PROCESSOR
SGUS025B – AUGUST 1998 – REVISED JUNE 2002
PP multiplier (continued)
When performing two simultaneous 8x8 split multiplies, the first input word contains unsigned byte operands
and the second input word contains signed or unsigned byte operands. These formats are shown in Figure 40
and Figure 41.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
XXXXXXXXXXXXXXXX
Unsigned Input 1b
Unsigned Input 1a
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
XXXXXXXXXXXXXXXXS
Signed Input 2b
S
Signed Input 2a
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
S
1b × 2b Signed Result
S
1a × 2a Signed Result
Figure 40. Signed Split Multiply Data Formats
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
XXXXXXXXXXXXXXXX
Unsigned Input 1b
Unsigned Input 1a
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
XXXXXXXXXXXXXXXX
Unsigned Input 2b
Unsigned Input 2a
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1b × 2b Unsigned Result
1a × 2a Unsigned Result
Figure 41. Unsigned Split Multiply Data Formats
PP program-flow-control unit architecture
The program-flow-control (pfc) unit performs instruction fetching and decoding, loop control, and handshaking
with the transfer controller. The pfc unit architecture is shown in Figure 43.
The PP has a three-stage fetch, address, execute (FAE) pipeline as shown in Figure 42. The pc, ipa, and ipe
registers point to the address of the instruction in each stage of the pipeline. On each cycle in which the pipeline
advances, ipa is copied into ipe, pc is copied into ipa, and the pc is incremented by one instruction (8 bytes).
pc
Instruction
T1
T2
T3
T4
T5
One
Fetch
Address
Execute
ipa
Two
Fetch
Address
Execute
Three
Fetch
Address
Execute
ipe
Figure 42. FAE-Instruction Pipeline
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