Datasheet

SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
88
10.11.4.1 ASR
Arithmetic shift 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 copies the original bit[31] of the register into the left-hand n bits of the
result. See Figure 10-4 on page 88.
You can use the ASR #n operation to divide the value in the register Rm by 2
n
, with the result being rounded
towards negative-infinity.
When the instruction is ASRS or when ASR #n is used in Operand2 with the instructions MOVS, MVNS, ANDS,
ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to the last bit shifted out, bit[n-1], of the
register Rm.
 If n is 32 or more, then all the bits in the result are set to the value of bit[31] of Rm.
 If n is 32 or more and the carry flag is updated, it is updated to the value of bit[31] of Rm.
Figure 10-4. ASR #3
10.11.4.2 LSR
Logical shift 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 sets the left-hand n bits of the result to 0. See Figure 10-5.
You can use the LSR #n operation to divide the value in the register Rm by 2
n
, if the value is regarded as an
unsigned integer.
When the instruction is LSRS or when LSR #n is used in Operand2 with the instructions MOVS, MVNS, ANDS,
ORRS, ORNS, EORS, BICS, TEQ or TST, the carry flag is updated to the last bit shifted out, bit[n-1], of the
register Rm.
 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.
Figure 10-5. LSR #3
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