ADSP-BF53x/BF56x Blackfin Processor Programming Reference
19-25
Vector Operations
“ASHIFT” Syntax
Both half-word registers in
src_reg
are shifted by the number of places
prescribed in
shift_magnitude
, and the result stored into
dest_reg
.
The sign of the shift magnitude determines the direction of the shift for
the
ASHIFT
versions.
• Positive shift magnitudes without the saturation flag ( – , S) pro-
duce Logical Left shifts.
• Positive shift magnitudes with the saturation flag ( – , S) produce
Arithmetic Left shifts.
• Negative shift magnitudes produce Arithmetic Right shifts.
In essence, the magnitude is the power of 2 multiplied by the
src_reg
number. Positive magnitudes cause multiplication ( N x 2
n
), whereas neg-
ative magnitudes produce division ( N x 2
-n
or N / 2
n
).
The
dest_reg
and
src_reg
are both pairs of 16-bit half registers. Satura-
tion of the result is optional.
Valid shift magnitudes for 16-bit
src_reg
are –16 t15, zero
included. If a number larger than these is supplied, the instruction masks
and ignores the more significant bits.
This instruction does not implicitly modify the
src_reg
values. Option-
ally,
dest_reg
can be the same D-register as
src_reg
. Using the same
D-register for the
dest_reg
and the
src_reg
explicitly modifies the source
register.
Options
The
ASHIFT
instruction supports the ( – , S) option, which saturates the
result.
Summary of Contents for ADSP-BF53x Blackfin
Page 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 486: ...Instruction Overview 13 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 512: ...Instruction Overview 14 26 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 604: ...Instruction Overview 15 92 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 688: ...Instruction Overview 18 48 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...