4.4.5. SMLALxy

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

Syntax

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 (see Conditional execution).

RdHi, RdLo

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.

Do not use r15 for RdHi, RdLo, Rn, or Rm.

Usage

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.

Condition 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.

Architectures

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, except the ARMv7-M profile.

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

Examples

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