SMLALxy

Signed Multiply-Accumulate with 16-bit operands and a 64-bit accumulator.

Show/hideSyntax

SMLAL<x><y>{cond} RdLo, RdHi, Rn, Rm

where:

<x>

is either B or T. B means use the bottom half (bits [15:0]) of Rn, T means use the top half (bits [31:16]) of Rn.

<y>

is either B or T. B means use the bottom half (bits [15:0]) of Rm, T means use the top half (bits [31:16]) of Rm.

cond

is an optional condition code.

RdLo, RdHi

are the destination registers. They also hold the accumulate value. RdHi and RdLo must be different registers.

Rn, Rm

are the registers holding the values to be multiplied.

Show/hideUsage

SMLALxy multiplies the signed integer from the selected half of Rm by the signed integer from the selected half of Rn, and adds the 32-bit result to the 64-bit value in RdHi and RdLo.

Show/hideRegister restrictions

You cannot use PC for any register.

You can use SP in ARM instructions but these are deprecated in ARMv6T2 and above. You cannot use SP in Thumb instructions.

Show/hideCondition flags

This instruction does not change the flags.

Note

SMLALxy cannot raise an exception. If overflow occurs on this instruction, the result wraps round without any warning.

Show/hideArchitectures

This ARM instruction is available in ARMv6 and above, and E variants of ARMv5T.

These 32-bit Thumb instructions are available in ARMv6T2 and above. For the ARMv7-M architecture, they are only available in an ARMv7E-M implementation.

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

Show/hideExamples

    SMLALTB     r2, r3, r7, r1
    SMLALBTVS   r0, r1, r9, r2

Show/hideSee also

Reference:
Copyright © 2010-2011 ARM. All rights reserved.ARM DUI 0489C
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