#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] );
  }