NXP Semiconductors LPC11U3x

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User manual Rev. 5.5 — 21 December 2016 458 of 523
NXP Semiconductors
UM10462
Chapter 24: LPC11U3x/2x/1x Appendix ARM Cortex-M0
• If n is 32 or more, then all the bits in the result are cleared to 0.
• If n is 33 or more and the carry flag is updated, it is updated to 0.
24.4.3.3.3 LSL
Logical shift left by n bits moves the right-hand 32-n bits of the register Rm, to the left by n
places, into the left-hand 32-n bits of the result, and it sets the right-hand n bits of the
result to 0. See Figure 84
.
You can use the LSL operation to multiply the value in the register Rm by 2
n
, if the value is
regarded as an unsigned integer or a two’s complement signed integer. Overflow can
occur without warning.
When the instruction is LSLS the carry flag is updated to the last bit shifted out, bit[32-n],
of the register Rm. These instructions do not affect the carry flag when used with LSL #0.
Remark:
• If n is 32 or more, then all the bits in the result are cleared to 0.
• If n is 33 or more and the carry flag is updated, it is updated to 0.
24.4.3.3.4 ROR
Rotate right by n bits moves the left-hand 32-n bits of the register Rm, to the right by n
places, into the right-hand 32-n bits of the result, and it moves the right-hand n bits of the
register into the left-hand n bits of the result. See Figure 24–85
.
When the instruction is RORS the carry flag is updated to the last bit rotation, bit[n-1], of
the register Rm.
Remark:
Fig 83. LSR #3
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Fig 84. LSL #3
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