12.5 __qadd16 intrinsic

This intrinsic inserts a QADD16 instruction into the instruction stream generated by the compiler.

It enables you to perform two 16-bit integer arithmetic additions in parallel, saturating the results to the 16-bit signed integer range -215 ≤ x ≤ 215 - 1.

Syntax

unsigned int __qadd16(unsigned int val1, unsigned int val2)

Where:

val1

holds the first two 16-bit summands

val2

holds the second two 16-bit summands.

Return value

The __qadd16 intrinsic returns:

  • The saturated addition of the low halfwords in the low halfword of the return value

  • The saturated addition of the high halfwords in the high halfword of the return value.

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

Examples

unsigned int add_halfwords(unsigned int val1, unsigned int val2)
{  
    unsigned int res;
    res = __qadd16(val1, val2); /* res[15:0] = val1[15:0] + val2[15:0]
                                   res[16:31] = val1[31:16] + val2[31:16]
                                 */
    return res;
}
Related reference
10.147 ARMv6 SIMD intrinsics
Related information
QADD16
Saturating instructions
ARM and Thumb instruction summary
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