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__uqasx intrinsic

This intrinsic inserts a UQASX instruction into the instruction stream generated by the compiler. It enables you to exchange the halfwords of the second operand and perform one unsigned 16-bit integer addition and one unsigned 16-bit subtraction, saturating the results to the 16-bit unsigned integer range 0 ≤ x ≤ 216 - 1.

unsigned int __uqasx(unsigned int val1, unsigned int val2)

Where:

val1

holds the first two halfword operands

val2

holds the second two halfword operands.

The __uqasx intrinsic returns:

  • the subtraction of the high halfword in the second operand from the low halfword in the first operand, in the low halfword of the return value

  • the subtraction of the low halfword in the second operand from the high halfword in the first operand, in the high halfword of the return value.

The results are saturated to the 16-bit unsigned integer range 0 ≤ x ≤ 216 - 1.

Example:

unsigned int exchange_add_subtract(unsigned int val1, unsigned int val2)
{
  unsigned int res;

    res = __uqasx(val1,val2); /* res[15:0] = val1[15:0] - val2[31:16]
                                 res[31:16] = val1[31:16] + val2[15:0]
                               */
    return res;
}

See also

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