Non-Confidential | PDF version | ARM DUI0375E | ||

| ||||

Home > ARMv6 SIMD Instruction Intrinsics > __smlsldx intrinsic |

This intrinsic inserts an `SMLSLDX`

instruction into the instruction stream generated by the compiler.

It enables
you to exchange the halfwords of the second operand, perform two
16-bit multiplications, adding the difference of the products to
a 64-bit accumulate operand. Overflow cannot occur during the multiplications
or the subtraction. Overflow can occur as a result of the 64-bit
addition, and this overflow is not detected. Instead, the result
wraps round to modulo 2^{64}.

```
unsigned long long __smlsldx(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

`__smlsld`

intrinsic returns the difference
of the product of each multiplication, added to the accumulate value.unsigned long long dual_multiply_diff_prods(unsigned int val1, unsigned int val2, unsigned long long val3) { unsigned int res; res = __smlsld(val1,val2,val3); /* p1 = val1[15:0] × val2[31:16] p2 = val1[31:16] × val2[15:0] res[63:0] = p1 - p2 + val3[63:0] */ return res; }