void setup() {
  // put your setup code here, to run once:
  volatile char *rowa, *outa, *rowb, *outb;
  volatile long i, j;
  rowa = 0x21; rowb = 0x24;
  outa = 0x22; outb = 0x25;
  *rowa = 0xff; *rowb = 0xff;
  while (1) {
    //=========================================P1
    //*outa = *outb = 0xff;
    //=========================================P2
    /**outa = 0xff;
      for (i = 0; i < 400000; i++);
      *outa = 0x00;
      *outb = 0xff;
      for (i = 0; i < 400000; i++);
      *outb = 0x00;*/
    //=========================================P3-P4
    /*for (j = 0; j < 8; j++)
      {
        *outa = 1 << j;
      for (i = 0; i < 400000; i++);
      }
       *outa = 0x00;
      for (j = 7; j >= 0; j--)
      {
        *outb = 1 << j;
      for (i = 0; i < 400000; i++);
      }
       *outb = 0x00;
      for (i = 0; i < 400000; i++);
      for (j = 0; j < 8; j++)
      {
        *outb = 1 << j;
      for (i = 0; i < 400000; i++);
      }
       *outb = 0x00;
      for (j = 7; j >= 0; j--)
      {
        *outa = 1 << j;
      for (i = 0; i < 400000; i++);
      }
       *outa = 0x00;
      for (i = 0; i < 400000; i++);*/
    //===========================================P3-P4 ALT
    /*int a[4]={0x03,0x0c,0x30,0xc0};
    for(j=0;j<4;j++)
    {
      *outa=a[j];
      for(i=0;i<400000;i++);
    }
    *outa=0x00;
    for(j=3;j>=0;j--)
    {
      *outb=a[j];
      for(i=0;i<400000;i++);
    }
    *outb=0x00;*/
    //===========================================P5
    /*int a[4]={0x03,0x0c,0x30,0xc0};
    for(j=0;j<4;j++)
    {
      *outa=a[j];
      for(i=0;i<400000;i++);
    }
    *outa=0x00;
    for(j=3;j>=0;j--)
    {
      *outb=a[j];
      for(i=0;i<400000;i++);
    }
    *outb=0x00;
    for(i=0;i<400000;i++);
    for(j=0;j<4;j++)
    {
      *outb=a[j];
      for(i=0;i<400000;i++);
    }
    *outb=0x00;
    for(j=3;j>=0;j--)
    {
      *outa=a[j];
      for(i=0;i<400000;i++);
    }
    *outa=0x00;*/
    //===========================================P6
    /*for (j = 0; j < 8; j = j + 2)
    {
      *outa = (1 << j) + (2 << j);
      for (i = 0; i < 400000; i++);
    }
    *outa = 0x00;
    for (j = 6; j >= 0; j = j - 2)
    {
      *outb = (1 << j) + (2 << j);
      for (i = 0; i < 400000; i++);
    }
    *outb = 0x00;
    for (i = 0; i < 400000; i++);
    for (j = 0; j < 8; j = j + 2)
    {
      *outb = (1 << j) + (2 << j);
      for (i = 0; i < 400000; i++);
    }
    *outb = 0x00;
    for (j = 6; j >= 0; j = j - 2)
    {
      *outa = (1 << j) + (2 << j);
      for (i = 0; i < 400000; i++);
    }
    *outa = 0x00;
    for (i = 0; i < 400000; i++);*/
    //===========================================P7
      /*int a[2]={0x0f,0xf0};
      for(i=0;i<2;i++)
      {
        *outa=a[i];
        for(j=0;j<400000;j++);
      }
      *outa=0x00;
      for(i=1;i>=0;i--)
      {
        *outb=a[i];
        for(j=0;j<400000;j++);
      }
      *outb=0x00;*/
    //===========================================P8
    /* *outa=0x55;
      *outb=0xAA;
      for(j=0;j<400000;j++);
      *outa=*outa+*outb;
      *outb=*outa-*outb;
      *outa=*outa-*outb;
      for(j=0;j<400000;j++);*/
    //==========================================P9
    /*for(j=0;j<8;j++)
      {
       *outa=*outb=1<<j;
      for(i=0;i<400000;i++);
      }*/
    //==========================================P10
    /*for (j = 7; j >= 0; j--)
      {
       *outa = *outb = 1 << j;
      for (i = 0; i < 400000; i++);
      }*/
  }
}