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Home > ARMv6 SIMD Instruction Intrinsics > __smlsd intrinsic |

This intrinsic inserts an `SMLSD`

instruction into the instruction stream generated by the compiler.

It enables
you to perform two 16-bit signed multiplications, take the difference
of the products, subtracting the high halfword product from the
low halfword product, and add the difference to a 32-bit accumulate
operand. The Q bit is set if the accumulation overflows. Overflow
cannot occur during the multiplications or the subtraction.

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