12.6 __qadd8 intrinsic

This intrinsic inserts a QADD8 instruction into the instruction stream generated by the compiler.

It enables you to perform four 8-bit integer additions, saturating the results to the 8-bit signed integer range -27 ≤ x ≤ 27 - 1.

Syntax

unsigned int __qadd8(unsigned int val1, unsigned int val2)

Where:

val1

holds the first four 8-bit summands

val2

holds the other four 8-bit summands.

Return value

The __qadd8 intrinsic returns:

  • The saturated addition of the first byte of each operand in the first byte of the return value

  • The saturated addition of the second byte of each operand in the second byte of the return value

  • The saturated addition of the third byte of each operand in the third byte of the return value

  • The saturated addition of the fourth byte of each operand in the fourth byte of the return value.

The returned results are saturated to the 8-bit signed integer range -27 ≤ x ≤ 27 - 1.

Examples

unsigned int add_bytes(unsigned int val1, unsigned int val2)
{
    unsigned int res;
    res = __qadd8(val1,val2); /* res[7:0] = val1[7:0] + val2[7:0]
                                 res[15:8] = val1[15:8] + val2[15:8]
                                 res[23:16] = val1[23:16] + val2[23:16]
                                 res[31:24] = val1[31:24] + val2[31:24]
                               */
    return res;
}
Related reference
10.147 ARMv6 SIMD intrinsics
Related information
QADD8
Saturating instructions
ARM and Thumb instruction summary
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