10.163 UMLAL

Unsigned Long Multiply, with optional Accumulate, with 32-bit operands and 64-bit result and accumulator.


UMLAL{S}{cond} RdLo, RdHi, Rn, Rm
is an optional suffix available in ARM state only. If S is specified, the condition flags are updated based on the result of the operation.
is an optional condition code.
RdLo, RdHi
are the destination registers. They also hold the accumulating value. RdLo and RdHi must be different registers.
Rn, Rm
are ARM registers holding the operands.


The UMLAL instruction interprets the values from Rn and Rm as unsigned integers. It multiplies these integers, and adds the 64-bit result to the 64-bit unsigned integer contained in RdHi and RdLo.

Register restrictions

Rn must be different from RdLo and RdHi in architectures before ARMv6.
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

If S is specified, this instruction:
  • Updates the N and Z flags according to the result.
  • Does not affect the C or V flags.


This ARM instruction is available in all versions of the ARM architecture.
This 32-bit Thumb instruction is available in ARMv6T2 and above.
There is no 16-bit version of this instruction in Thumb.


    UMLALS      r4, r5, r3, r8
Related reference
10.8 Condition code suffixes
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