Barrel Shifter (Shifter)
2-44
ADSP-BF535 Blackfin Processor Hardware Reference
In this instruction, the 40-bit accumulator is packed into a 16-bit half reg-
ister. The result from MAC1 must be transferred to a high half of a
destination register and the result from MAC0 must be transferred to the
low half of the same destination register.
The operand type determines the correct bits to extract from the accumu-
lator and deposit in the 16-bit destination register. See
“Multiply Without
Accumulate” on page 2-40
.
R3 = ( A1 += R1.H * R2.L ), R2=( A0 += R1.L * R2.L ) ;
In this instruction, the 40-bit accumulators are packed into two 32-bit
registers. The registers must be register pairs (
R[1:0]
;
R[3:2] ; R[5:4]
; R[7:6]
)
R3.H = ( A1 += R1.H * R2.L ), A0 += R1.L * R2.L ;
This instruction is an example of one accumulator—but not the other—
being transferred to a register. Either a 16- or 32-bit register may be speci-
fied as the destination register.
Barrel Shifter (Shifter)
The shifter provides bitwise shifting functions for 16- or 32-bit inputs,
yielding a 16-, 32-, or 40-bit output. These functions include arithmetic
shift, logical shift, rotate, and various bit-test, set, pack, unpack and expo-
nent-detection functions. These shift functions can be combined to
implement numerical format control, including full floating-point
representation.
Shifter Operations
The shifter instructions (
>>>
,
>>
,
ASHIFT
,
LSHIFT
,
ROT
) can be used various
ways, depending on the underlying arithmetic requirements.
ASHIFT
and
>>>
represents the arithmetic shift.
LSHIFT
and
>>
represent the logical
shift.
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...