Analog Devices ADSP-BF53x Blackfin Reference page 509

The sign of the rotate magnitude determines the direction of the rotation.
• Positive rotate magnitudes produce Left rotations.
• Negative rotate magnitudes produce Right rotations.
Valid rotate magnitudes are –32 through +31, zero included. The Rotate
instruction masks and ignores bits that are more significant than those
allowed. The distance is determined by the lower 6 bits (sign extended) of
the
shift_magnitude
Unlike shift operations, the Rotate instruction loses no bits of the source
register data. Instead, it rearranges them in a circular fashion. However,
the last bit rotated out of the register remains in the
returned to the register. Because rotates are performed all at once and not
one bit at a time, rotating one direction or another regardless of the rotate
magnitude produces no advantage. For instance, a rotate right by two bits
is no more efficient than a rotate left by 30 bits. Both methods produce
identical results in identical execution time.
The D-register versions of this instruction rotate all 32 bits. The Accumu-
lator versions rotate all 40 bits of those registers.
The D-register versions of this instruction do not implicitly modify the
values. Optionally,
src_reg
. Doing this explicitly modifies the source register.
src_reg
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
.
can be the same D-register as
dest_reg
Shift/Rotate Operations
bit, and is not
CC
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