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Home > ARMv6 SIMD Instruction Intrinsics > __smlald intrinsic |

This intrinsic inserts an `SMLALD`

instruction into the instruction stream generated by the compiler.

It enables
you to perform two signed 16-bit multiplications, adding both results
to a 64-bit accumulate operand. Overflow is only possible as a result
of the 64-bit addition. This overflow is not detected if it occurs.
Instead, the result wraps around modulo 2^{64}.

` unsigned long long __smlald(unsigned int `

`val1`

,
unsigned int `val2`

, unsigned long long
`val3`

)

Where:

`val1`

holds the first halfword operands for each multiplication

`val2`

holds the second halfword operands for each multiplication

`val3`

holds the accumulate value.

The `__smlald`

intrinsic returns the product
of each multiplication added to the accumulate value.

unsigned int dual_multiply_accumulate(unsigned int val1, unsigned int val2, unsigned int val3) { unsigned int res; res = __smlald(val1,val2,val3); /* p1 = val1[15:0] × val2[15:0] p2 = val1[31:16] × val2[31:16] sum = p1 + p2 + val3[63:32][31:0] res[63:32] = sum[63:32] res[31:0] = sum[31:0] */ return res; }