12.44 __uhasx intrinsic

This intrinsic inserts a UHASX instruction into the instruction stream generated by the compiler.

It enables you to exchange the halfwords of the second operand, add the high halfwords and subtract the low halfwords, halving the results.

Syntax

unsigned int __uhasx(unsigned int val1, unsigned int val2)
Where:
val1
holds the first operand for the subtraction in the low halfword, and the first operand for the addition in the high halfword
val2
holds the second operand for the subtraction in the high halfword, and the second operand for the addition in the low halfword.

Return value

The __uhasx intrinsic returns:
  • The halved subtraction of the high halfword in the second operand from the low halfword in the first operand.
  • The halved addition of the high halfword in the first operand and the low halfword in the second operand.

Example

unsigned int exchange_add_subtract(unsigned int val1, unsigned int val2)
{
    unsigned int res;
    res = __uhasx(val1,val2); /* res[15:0] = (val1[15:0] - val2[31:16]) >> 1
                                 res[31:16] = (val1[31:16] + val2[15:0]) >> 1
                                */
    return res;
}
Related reference
9.144 ARMv6 SIMD intrinsics
Related information
UHASX
ARM and Thumb instruction summary
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