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Reverse the byte order in each halfword independently.

REV16{ cond } Rd , Rn



is an optional condition code.


is the destination register.


is the register holding the operand.


You can use this instruction to change endianness. REV16 converts 16-bit big-endian data into little-endian data or 16-bit little-endian data into big-endian data.

Register restrictions

You cannot use PC for any register.

You can use SP in ARM instructions but this is deprecated in ARMv6T2 and above. You cannot use SP in Thumb instructions.

Condition flags

This instruction does not change the flags.

16-bit instructions

The following form of this instruction is available in Thumb code, and is a 16-bit instruction:

REV16 Rd, Rm

Rd and Rm must both be Lo registers.


This ARM instruction is available in ARMv6 and above.

This 32-bit Thumb instruction is available in ARMv6T2 and above.

This 16-bit Thumb instruction is available in ARMv6 and above.


 REV16   r0, r0