#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define DDR DDRB
#define  NBIT PB0
#define BYTES (NUM_LEDS*3) // ogni led ha 3 colori
#define NUM_LEDS 32        
#define PORT PORTB        
#define LEDPIN PORTB0     // pin 8
uint8_t* leds = NULL;

void setup() { 
  DDRB = DDRB | B00000001;          // imposta il pin 8 come output
  leds = (uint8_t*) malloc(BYTES);  // alloco area di memoria
  memset(leds, 0, BYTES);           // azzero l'area di memoria
}



void loop()
{
//cambia colore e luminosità
 aggiornaLed();
}

uint8_t vp[NUM_LEDS];
void aggiornaLed()
{
    for(int i= 0; i< BYTES -2; i += 3)
  {
    vp[i] = 0;  //0 verde, 1 rosso, 2 blu
    vp[i+ 1] = 255;  
    vp[i+ 2] = 0;
    
  }
    pix_show(NUM_LEDS*3, vp);
}

volatile void pix_show(uint8_t nb, uint8_t *vp) {
  sbi(DDR, NBIT); // output
  cbi(PORT, NBIT);
  cli();
  asm volatile (
    "lwhile0:\n\t"
    "ld r24, %a[vp]+ \n\t"
    "ldi r25, 8 \n\t"
    "lwhile:\n\t"
    "nop \n\t"
    "sbi %[port],%[nbit] \n\t"
    "rjmp .+0 \n\t"
    "rjmp .+0 \n\t"
    "sbrs r24, 7 \n\t"
    "cbi %[port], %[nbit] \n\t"
    "add r24, r24 \n\t"
    "subi r25, 1 \n\t"
    "breq vnextb \n\t"
    "rjmp .+0 \n\t"
    "cbi %[port], %[nbit] \n\t"
    "rjmp .+0 \n\t"
    "nop \n\t"
    "rjmp lwhile \n\t"
    "vnextb:\n\t"
    "subi %[nb], 1 \n\t"
    "cbi %[port],%[nbit] \n\t"
    "brne lwhile0 \n\t"
    : [vp] "+e" (vp)
    : [nb] "d" (nb),
    [port] "i" (_SFR_IO_ADDR(PORT)),
    [nbit] "i" (NBIT)
    : "r24", "r25"
  );
  sei();
  cbi(DDR, NBIT);
}