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13.169 UHSAX

Unsigned halving parallel subtract and add halfwords with exchange.


UHSAX{cond} {Rd}, Rn, Rm



is an optional condition code.


is the destination register.

Rm, Rn

are the ARM registers holding the operands.


This instruction exchanges the two halfwords of the secondoperand, then performs a subtraction on the two top halfwords ofthe operands and an addition on the bottom two halfwords. It halvesthe results and writes them into the corresponding halfwords ofthe destination. This cannot cause overflow.

Register restrictions

You cannot use PC for any operand.

You can use SP in A32 instructions but this is deprecated. You cannot use SP in T32 instructions.

Condition flags

This instruction does not affect the N, Z, C, V, Q, or GEflags.


The 32-bit instruction is available in A32 and T32.

There is no 16-bit version of this instruction in T32.

Related reference

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