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__sadd16 intrinsic

This intrinsic inserts an SADD16 instruction into the instruction stream generated by the compiler. It enables you to perform two 16-bit signed integer additions. The GE bits in the Application Program Status Register (APSR) are set according to the results of the additions.

unsigned int __sadd16(unsigned int val1, unsigned int val2)

Where:

val1

holds the first two 16-bit summands

val2

holds the second two 16-bit summands.

The __sadd16 intrinsic returns:

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

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

Each bit in APSR.GE is set or cleared for each byte in the return value, depending on the results of the operation. If res is the return value, then:

  • if res[15:0] ≥ 0 then APSR.GE[1:0] = 11 else 00

  • if res[31:16] ≥ 0 then APSR.GE[3:2] = 11 else 00.

Example:

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

    res = __sadd16(val1,val2); /* res[15:0] = val1[15:0] + val2[15:0]
                                  res[31:16] = val1[31:16] + val2[31:16]
                                */
    return res;
}

See also

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