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Home > ARMv6 SIMD Instruction Intrinsics > __smlsdx intrinsic |

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:

`val1`

holds the first halfword operands for each multiplication

`val2`

holds the second halfword operands for each multiplication

`val3`

holds the accumulate value.

The `__smlsd`

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

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; }