Analog Devices ADSP-BF53x Blackfin Reference page 494

Instruction Overview
A0 = ASHIFT A0 BY Dreg_lo ;
A1 = ASHIFT A1 BY Dreg_lo ;
Syntax Terminology
:
Dreg R7–0
:
Dreg_lo_hi R7–0.L
:
Dreg_lo R7–0.L
: 4-bit unsigned field, with a range of 0 through 15
uimm4
: 5-bit unsigned field, with a range of 0 through 31
uimm5
: optional "(S)" (without the quotes) to invoke saturation of the
opt_sat
result. Not optional on versions that show "(S)" in the syntax.
Instruction Length
In the syntax, comment (a) identifies 16-bit instruction length. Comment
(b) identifies 32-bit instruction length.
Functional Description
The Arithmetic Shift instruction shifts a registered number a specified dis-
tance and direction while preserving the sign of the original number. The
sign bit value back-fills the left-most bit positions vacated by the arith-
metic right shift.
Specific versions of arithmetic left shift are supported, too. Arithmetic left
shift saturates the result if the value is shifted too far. A left shift that
would otherwise lose nonsign bits off the left-hand side saturates to the
maximum positive or negative value instead.
14-8 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
/* arithmetic right shift (b)*/
/* arithmetic right shift (b)*/
,
R7–0.H