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Signed Most significant word Multiply.


SMMUL{R}{cond} {Rd}, Rn, Rm



is an optional parameter. If R is present, the result is rounded, otherwise it is truncated.


is an optional condition code.


is the destination register.

Rn, Rm

are the registers holding the operands.


is a register holding the value to be added or subtracted from.


SMMUL multiplies the 32-bit values from Rn and Rm, and stores the most significant 32 bits of the 64-bit result to Rd.

If the optional R parameter is specified, 0x80000000 is added before extracting the most significant 32 bits. This has the effect of rounding the result.

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.


This ARM instruction is available in ARMv6 and above.

This 32-bit Thumb instruction is available in ARMv6T2 and above. For the ARMv7-M architecture, it is only available in an ARMv7E-M implementation.

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


    SMMULGE     r6, r4, r3
    SMMULR      r2, r2, r2