ADSP-2126x SHARC Processor Hardware Reference
2-41
Processing Elements
results in either
MRF
or
MRB
, without regard to the state of the
MODE1
regis-
ter. With this arrangement, code can use the result registers as primary
and alternate accumulators, or code can use these registers as two parallel
accumulators. This feature facilitates complex math.
The
MODE1
register controls the access to alternate registers.
MODE1
. The following bits in
MODE1
control
alternate registers (a 1 enables the alternate set):
• Secondary registers for computational unit results. Bit 2 (
SRCU
)
• Secondary registers for hi register file,
R8
–
R15
and
S8
–
S15
.
Bit 7 (
SRRFH
)
• Secondary registers for lo register file,
R0
–
R7
and
S0
–
S7
.
Bit 10 (
SRRFL
)
The following example demonstrates how code should handle the maxi-
mum one cycle of latency—from the instruction that sets the bit in the
MODE1
register to the point when the alternate registers may be accessed.
Note that it is possible to use any instruction that does not access the
switching register file instead of using a
NOP
instruction.
BIT SET MODE1 SRRFL; /* activate alternate reg. file */
NOP; /* wait for access to alternates */
R0 = 7;
Multifunction Computations
The DSP supports multiple parallel (multifunction) computations by
using the many parallel data paths within its computational units. These
instructions complete in a single cycle, and they combine parallel opera-
tion of the multiplier and the ALU or dual ALU functions. The multiple
operations perform as if they were in corresponding single function
computations. Multifunction computations also handle flags in the same
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 ...