12.50 __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.

Syntax

unsigned int __uqasx(unsigned int val1, unsigned int val2)
Where:
val1
holds the first two halfword operands
val2
holds the second two halfword operands.

Return value

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.

Examples

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;
}
Related reference
9.143 ARMv6 SIMD intrinsics
Related information
UQASX
ARM and Thumb instruction summary
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