ARM Compiler armcc User Guide : 12.30 _

12.30 __smuadx intrinsic

This intrinsic inserts an SMUADX instruction into the instruction stream generated by the compiler.

It enables you to exchange the halfwords of the second operand, perform two 16-bit signed integer multiplications, and add the products together. Exchanging the halfwords of the second operand produces top × bottom and bottom × top multiplication. The Q flag is set if the addition overflows. The multiplications cannot overflow.

Syntax

unsigned int __smuadx(unsigned int val1, unsigned int val2)

Where:

val1: holds the first halfword operands for each multiplication
val2: holds the second halfword operands for each multiplication.

Return value

The __smuadx intrinsic returns the products of the two 16-bit signed multiplications.

Examples

unsigned int exchange_dual_multiply_prods(unsigned int val1, unsigned int val2)
{
    unsigned int res;
    res = __smuadx(val1,val2); /* val2[31:16][15:0] = val2[15:0][31:16]
                                  p1 = val1[15:0] × val2[15:0]
                                  p2 = val1[31:16] × val2[31:16]
                                  res[31:0] = p1 + p2
                                */
    return res;
}

Related reference

10.147 ARMv6 SIMD intrinsics

Related information

SMUADX

ARM and Thumb instruction summary

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