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.


unsigned int __smuadx(unsigned int val1, unsigned int val2)
holds the first halfword operands for each multiplication
holds the second halfword operands for each multiplication.

Return value

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


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
9.144 ARMv6 SIMD intrinsics
Related information
ARM and Thumb instruction summary
Non-ConfidentialPDF file icon PDF versionARM DUI0375F
Copyright © 2007, 2008, 2011, 2012, 2014 ARM. All rights reserved.