Click above to get retro games delivered to your door ever month!

Synopsis:
    #include <mmintrin.h>
    __m64 _m_packsswb(__m64 *m1, __m64 *m2);

Description:
    Convert signed packed words into signed packed bytes by packing (with
    signed saturation) the low-order bytes of the signed word elements from
    m1 and m2 into the respective signed bytes of the result.  If the signed
    values in the word elements of m1 and m2 are smaller than 0x80, the
    result elements are clamped to 0x80.  If the signed values in the word
    elements of m1 and m2 are larger than 0x7f, the result elements are
    clamped to 0x7f.


                     m2                         m1
         -------------------------  -------------------------
         |b7 b6|b5 b4|b3 b2|b1 b0|  |b7 b6|b5 b4|b3 b2|b1 b0|
         -------------------------  -------------------------
            |     |     |     |        |     |     |     |
            |     |     |     `--.  .--'     |     |     |
            |     |     `-----.  |  |  .-----'     |     |
            |     `--------.  |  |  |  |  .--------'     |
            `-----------.  |  |  |  |  |  |  .-----------'
                        |  |  |  |  |  |  |  |
                        V  V  V  V  V  V  V  V
                       -------------------------
                       |b7|b6|b5|b4|b3|b2|b1|b0|
                       -------------------------
                             result


Returns:
    The result of packing, with signed saturation, 16-bit signed words into
    8-bit signed bytes is returned.

Example:
    #include <stdio.h>
    #include <mmintrin.h>

    #define AS_BYTES "%2.2x %2.2x %2.2x %2.2x " \
                     "%2.2x %2.2x %2.2x %2.2x"
    #define AS_WORDS "%4.4x %4.4x %4.4x %4.4x"
    #define AS_DWORDS "%8.8lx %8.8lx"

    __m64   a;
    __m64   b = { 0x0004000300020001 };
    __m64   c = { 0xff7fff800080007f };

    void main()
      {
        a = _m_packsswb( b, c );
        printf( "m2="AS_WORDS" "
                "m1="AS_WORDS"\n"
                "mm="AS_BYTES"\n",
            c._16[3], c._16[2], c._16[1], c._16[0],
            b._16[3], b._16[2], b._16[1], b._16[0],
            a._8[7], a._8[6], a._8[5], a._8[4],
            a._8[3], a._8[2], a._8[1], a._8[0] );
      }

    produces the following:

    m2=ff7f ff80 0080 007f m1=0004 0003 0002 0001
    mm=80 80 7f 7f 04 03 02 01

Classification:
    Intel

Systems:
    MACRO

See Also:
    _m_empty, _m_packssdw, _m_packuswb