ADSP-2126x SHARC Processor Hardware Reference
4-19
Data Address Generators
DAGs, Registers, and Memory
DAG registers are part of the DSP’s universal register (
Ureg
) set. Programs
may load the DAG registers from memory, from another universal regis-
ter, or with an immediate value. Programs may store DAG registers’
contents to memory or to another universal register.
The DAG’s registers support the bidirectional register-to-register transfers
that are described in
“SIMD (Computational) Operations” on page 2-50
.
When the DAG register is a source of the transfer, the destination can be a
register file data register. This transfer results in the contents of the single
source register being duplicated in complementary data registers in each
processing element.
Programs should use care in the case where the DAG register is a destina-
tion of a transfer from a register file data register source. Programs should
use a conditional operation to select either one processing element or nei-
ther as the source. Having both processing elements contribute a source
value results in the PEx element’s write having precedence over the PEy
element’s write.
In the case where a DAG register is both source and destination, the data
move operation executes the same as it would if SIMD mode were dis-
abled (
PEYEN
cleared).
DAG Register-to-Bus Alignment
There are three word alignment types for DAG registers and PM or DM
data buses: normal word, extended-precision normal word, and long
word.
The DAGs align normal word (32-bit) addressed transfers to the low order
bits of the buses. These transfers between memory and 32-bit DAG1 or
DAG2 registers use the 64-bit DM and PM data buses.
illus-
trates these transfers.
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 ...