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SWP and SWPB
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| Home > ARM and Thumb Instructions > SWP and SWPB | |||
Swap data between registers and memory.
SyntaxSWP{B}{cond}Rt,Rt2, [Rn]
where:
condis an optional condition code.
Bis an optional suffix. If
Bis present, a byte is swapped. Otherwise, a 32-bit word is swapped.Rtis the destination register.
RtRt2is the source register.
Rt2RtRt2Rncontains the address in memory.
RnRtRt2Rn
You can use SWP and SWPB to implement
semaphores:
Data from memory is loaded into
RtThe contents of
Rt2If
Rt2Rt
The use of SWP and SWPB is deprecated
in ARMv6 and above. You can use LDREX and STREX instructions
to implement more sophisticated semaphores in ARMv6 and above.
These ARM instructions are available in all versions of the ARM architecture.
There are no Thumb SWP or SWPB instructions.
| Copyright © 2011-2012 ARM. All rights reserved. | ARM DUI 0588B |
| Non-Confidential | ID062912 |
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| Home > ARM and Thumb Instructions > SWP and SWPB |
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