ADSP-2126x SHARC Processor Hardware Reference
3-5
Program Sequencer
• Jumps
• Subroutine calls and returns
• Interrupts and returns
• Loops
Instruction Cache
Usually, the sequencer fetches an instruction from memory on each cycle.
Occasionally, bus constraints prevent some of the data and instructions
from being fetched in a single cycle. To alleviate these data flow conflicts,
the DSP has a large 32-location instruction cache that caches instructions
that cause these conflicts. This solution removes the need to fetch the
offending instruction from memory, which frees both memory blocks and
data buses for data accesses. Except for enabling or disabling, the caches
operation is completely automatic and transparent, requiring no user
intervention.
For more information, see “Using the Cache” on page 3-8.
Bus Conflicts
A bus is comprised of two parts: the address bus and the data bus. Because
the bus can be accessed continually by different sources (illustrated in
), there is a potential for bus or block
conflicts
.
Figure 3-2. Pipelined Execution Cycles
CLOCK CYCLES
EXECUTE
INSTRUCTION
DECODE
INSTRUCTION
FETCH
INSTRUCTION
1
2
3
4
5
0x08
0x08
0x08
0x09
0x09
0x09
0x0A
0x0A
0x0A
0x0B
0x0B
0x0C
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...