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

Description:
    The signed or unsigned 8-bit bytes of m2 are subtracted from the
    respective signed or unsigned 8-bit bytes of m1 and the result is stored
    in memory.  If any result element does not fit into 8 bits (underflow or
    overflow), the lower 8 bits of the result elements are stored (i.e.,
    truncation takes place).

Returns:
    The result of subtracting the packed bytes of one 64-bit multimedia
    value from another 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"

    __m64   a;
    __m64   b = { 0x0123456789abcdef };
    __m64   c = { 0xfedcba9876543210 };

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

    m1=01 23 45 67 89 ab cd ef
    m2=fe dc ba 98 76 54 32 10
    mm=03 47 8b cf 13 57 9b df

Classification:
    Intel

Systems:
    MACRO

See Also:
    _m_empty, _m_psubd, _m_psubsb, _m_psubsw, _m_psubusb, _m_psubusw,
    _m_psubw