ARM VERSION 1.2 User Manual
Page 135
ARM Instruction Reference
ARM DUI 0068B
Copyright © 2000, 2001 ARM Limited. All rights reserved.
4-25
ASR
Arithmetic shift right by
n
bits divides the value contained in
Rm
by 2
n
, if the contents
are regarded as a two’s complement signed integer. The original bit[31] is copied into
the left-hand
n
bits of the register.
LSR and LSL
Logical shift right by
n
bits divides the value contained in
Rm
by 2
n
, if the contents are
regarded as an unsigned integer. The left-hand
n
bits of the register are set to 0.
Logical shift left by
n
bits multiplies the value contained in
Rm
by 2
n
, if the contents are
regarded as an unsigned integer. Overflow may occur without warning. The right-hand
n
bits of the register are set to 0.
ROR
Rotate right by
n
bits moves the right-hand n bits of the register into the left-hand
n
bits
of the result. At the same time, all other bits are moved right by
n
bits (see Figure 4-1).
Figure 4-1 ROR
RRX
Rotate right with extend shifts the contents of
Rm
right by one bit. The carry flag is
copied into bit[31] of
Rm
(see Figure 4-2 on page 4-26).
The old value of bit[0] of
Rm
is shifted out to the carry flag if the
S
suffix is specified (see
The carry flag on page 4-26).
31
1 0
Carry
Flag
...