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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; }