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ARM INSTRUCTION SET S3C2410A
3-14
Rotate right (ROR) operations reuse the bits which "overshoot" in a logical shift right operation by reintroducing them
at the high end of the result, in place of the zeros used to fill the high end in logical right operations. For example,
ROR #5 is shown in Figure 3-9.
31
Contents of Rm
Value of Operand 2
0
carry out
45
Figure 3-9. Rotate Right
The form of the shift field which might be expected to give ROR #0 is used to encode a special function of the barrel
shifter, rotate right extended (RRX). This is a rotate right by one bit position of the 33 bit quantity formed by
appending the CPSR C flag to the most significant end of the contents of Rm as shown in Figure 3-10.
31
Contents of Rm
Value of Operand 2
01
carry out
C
in
Figure 3-10. Rotate Right Extended