  static void  Ins_SVTCA( INS_ARG )
  {
    Short  A, B;
    (void)args;

    if ( CUR.opcode & 1 )
        A = 0x4000;
    else
        A = 0;

    B = A ^ 0x4000;

    CUR.GS.freeVector.x = A;
    CUR.GS.projVector.x = A;
    CUR.GS.dualVector.x = A;

    CUR.GS.freeVector.y = B;
    CUR.GS.projVector.y = B;
    CUR.GS.dualVector.y = B;

    COMPUTE_Funcs();
  }

The product reads data past the end, or before the beginning, of the intended buffer.