Setting DAG Modes
4-8
ADSP-2126x SHARC Processor Hardware Reference
alternate registers may be accessed. Note that programs should use a
NOP
instruction for the wait period.
BIT SET MODE1 SRD1L; /* Activate alternate dag1 lo regs */
NOP; /* Wait for access to alternates */
R0 = DM(i0,m1);
Bit-Reverse Addressing Mode
The
BR0
and
BR8
bits in the
MODE1
register enable the bit-reverse addressing
mode where addresses are output in reverse bit order. When
BR0
is set
(=1), DAG1 bit-reverses 32-bit addresses output from
I0
. When
BR8
is set
(=1), DAG2 bit-reverses 32-bit addresses output from
I8
. The DAGs only
bit-reverse the address output from
I0
or
I8
; the contents of these registers
are not reversed. Bit-reverse addressing mode effects both pre-modify and
post-modify operations. The following example demonstrates how
bit-reverse mode effects address output:
BIT SET Mode1 BR0; /* Enables bit-rev. addressing for DAG1 */
IO = 0x83000 /* Loads I0 with the bit reverse of the
buffer’s base address DM(0xC1000) */
M0 = 0x4000000; /* Loads M0 with value for post-modify, which
is the bit reverse value of the modifier
value M0 = 32 */
R1 = DM(I0,M0); /* Loads r1 with contents of DM address
DM(0xC1000), which is the bit-reverse of
0x83000, then post–modifies I0 for the next
access with (0 0x4000000) = 0x4083000,
which is the bit-reverse of DM(0xC1020) */
In addition to bit-reverse addressing, the DSP supports a bit-reverse
instruction (
BITREV
). This instruction bit-reverses the contents of the
selected register. For more information on the
BITREV
instruction, see
“Modifying DAG Registers” on page 4-17
ADSP-21160 SHARC DSP
Instruction Set Reference
.
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...