Barrel Shifter (Shifter)
2-48
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
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 2-44
.
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-, 32-, or 40-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 exponent detection functions. These shift functions can be
combined to implement numerical format control, including full float-
ing-point representation.
Shifter Operations
The shifter instructions (
>>>
,
>>
,
<<
,
ASHIFT
,
LSHIFT
,
ROT
) can be used var-
ious ways, depending on the underlying arithmetic requirements. The
ASHIFT
and
>>>
instructions represent the arithmetic shift. The
LSHIFT
,
<<
, and
>>
instructions represent the logical shift.
Содержание ADSP-BF53x Blackfin
Страница 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 486: ...Instruction Overview 13 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 512: ...Instruction Overview 14 26 ADSP BF53x BF56x Blackfin Processor Programming Reference...
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Страница 688: ...Instruction Overview 18 48 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 780: ...Product Identification Register 21 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 994: ...Instructions Listed By Operation Code C 194 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Страница 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...