ARM 学习笔记之5： Shift operations (LSR)

最新推荐文章于 2024-09-29 19:33:37 发布

LDWJ2016

最新推荐文章于 2024-09-29 19:33:37 发布

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本文详细介绍了逻辑右移指令LSR的功能和使用方法。LSR将寄存器中的左32-n位向右移动n位，清空结果的左n位。当用于算术操作时，可以实现寄存器中值除以2^n的操作。文章还提到了LSR在特定指令中如何更新进位标志。

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1) Logical shift right (LSR)

Logical shift right by n bits moves the left-hand 32-n bits of a register to the right by n places, into the
right-hand 32-n bits of the result. It sets the left-hand n bits of the result to 0.
You can use the LSR #n operation to divide the value in the register Rm by 2n, 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.
--------------------------- Note ----------------------------------------------------
• 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 fl
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