This intrinsic inserts an SMLSDX instruction into the instruction stream generated by the compiler. It enables you to exchange the halfwords in the second operand, then perform two 16-bit signed multiplications. The difference of the products is added to a 32-bit accumulate operand. The Q bit is set if the addition overflows. Overflow cannot occur during the multiplications or the subtraction.

unsigned int__smlsdx(unsigned int val1, unsigned int val2, unsigned int val3)

Where:

The __smlsd intrinsic returns the difference of the product of each multiplication, added to the accumulate value.

Example:

unsigned int dual_multiply_diff_prods(unsigned int val1, unsigned int val2, unsigned int val3)
{
  unsigned int res;

    res = __smlsd(val1,val2,val3); /* p1 = val1[15:0] × val2[31:16]
                                      p2 = val1[31:16] × val2[15:0]
                                      res[31:0] = p1 - p2 + val3[31:0]
                                    */
    return res;
}