ADSP-2126x SHARC Processor Hardware Reference
3-7
Program Sequencer
The cache places instructions in entries according to the four LSBs of the
instruction’s address. When the sequencer checks for an instruction to
fetch from the cache, it uses the four address LSBs as an index to a cache
set. Within that set, the sequencer checks the addresses of the two entries
as it looks for the needed instruction. If the cache contains the instruction,
the sequencer uses the entry and updates the
LRU
bit (if necessary) to indi-
cate the entry did not contain the needed instruction.
When the cache does not contain a needed instruction, it loads a new
instruction and its address and places them in the least recently used entry
of the appropriate cache set. The cache then toggles the
LRU
bit, if
necessary.
Block Conflicts
A bus conflict occurs when an instruction fetch and a data access are made
on the same bus. Similarly, a block conflict occurs when multiple accesses
Figure 3-3. Instruction Cache Architecture
INSTRUCTIONS
SET
0
SET
1
SET
2
SET
13
SET
14
SET
15
ADDRESSES
BITS (23-4)
LRU
BIT
VALID
BIT
ENTRY 0
ENTRY 0
ENTRY 0
ENTRY 1
ENTRY 1
ENTRY 1
ENTRY 0
ENTRY 0
ENTRY 0
ENTRY 1
ENTRY 1
ENTRY 1
ADDRESSES
BITS (3-0)
0000
0001
0010
1101
1110
1111
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 ...