DAG Operations
4-18
ADSP-2126x SHARC Processor Hardware Reference
The
MODIFY
instruction modifies addresses in any DAG index register
(
I0
-
I15
) without accessing memory. If the
I
register’s corresponding
B
and
L
registers are set up for circular buffering, a
MODIFY
instruction performs
the specified buffer wraparound (if needed). The syntax for
MODIFY
is sim-
ilar to post-modify addressing (index, then modifier). The
MODIFY
instruction accepts either a 32-bit immediate value or an
M
register as the
modifier. The following example adds 4 to
I1
and updates
I1
with the
new value:
MODIFY(I1,4);
The
BITREV
instruction modifies and bit-reverses addresses in any DAG
index register (
I0
-
I15
) without accessing memory. This instruction is
independent of the bit-reverse mode. The
BITREV
instruction adds a 32-bit
immediate value to a DAG index register, bit-reverses the result, and
writes the result back to the same index register. The following example
adds 4 to
I1
, bit-reverses the result, and updates
I1
with the new value:
BITREV(I1,4);
Addressing in SISD and SIMD Modes
Single-Instruction, Multiple-Data (SIMD) mode (
PEYEN
bit=1) does not
change the addressing operations in the DAGs, but it does change the
amount of data that moves during each access. The DAGs put the same
addresses on the address buses in SIMD and Single-Instruction Sin-
gle-Data (SISD) modes. In SIMD mode, the DSP’s memory and
processing elements get data from the named (explicit) locations in the
instruction syntax as well as complementary (implicit) locations. For more
information on data moves between registers, see
tional) Operations” on page 2-50
.
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 ...