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__uadd16 intrinsic

This intrinsic inserts a UADD16 instruction into the instruction stream generated by the compiler. It enables you to perform two 16-bit unsigned integer additions.

The GE bits in the APSR are set according to the results.

unsigned int __uadd16(unsigned int val1, unsigned int val2)

Where:

val1

holds the first two halfword summands for each addition

val2

holds the second two halfword summands for each addition.

The __uadd16 intrinsic returns:

  • the addition of the low halfwords in each operand, in the low halfword of the return value

  • the addition of the high halfwords in each operand, 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] ≥ 0x10000 then APSR.GE[0] = 11 else 00

  • if res[31:16] ≥ 0x10000 then APSR.GE[1] = 11 else 00.

Example:

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

    res = __uadd16(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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