This intrinsic inserts a QSAX instruction into the instruction stream generated by the compiler. It enables you to exchange the halfwords of one operand, then subtract the high halfwords and add the low halfwords, saturating the results to the 16-bit signed integer range -2¹⁵ ≤ x ≤ 2¹⁵ - 1.

unsigned int __qsax(unsigned int val1, unsigned int val2)

where:

The __qsax intrinsic returns:

The returned results are saturated to the 16-bit signed integer range -2¹⁵ ≤ x ≤ 2¹⁵ - 1.

Example:

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

    res = __qsax(val1,val2); /* res[15:0] = val1[15:0] + val2[31:16]
                                res[31:16] = val1[31:16] - val2[15:0]
                              */
                             /* Alternative equivalent representation:
                                val2[15:0][31:16] = val2[31:16][15:0]
                                res[15:0] = val1[15:0] + val2[15:0]
                                res[31:16] = val[31:16] - val2[31:16]
                              */
    return res;
}