/* Showing off some patterns to practice our bit-twiddling */

// ------- Preamble -------- //
#include <avr/io.h>
#include <avr/power.h>
#include <util/delay.h>                     /* Functions to waste time */

#define DELAYTIME 85                                   /* milliseconds */
#define LED_PORT                PORTB
#define LED_DDR                 DDRB

int main(void) {

  uint8_t i;
  uint8_t repetitions;
  uint8_t whichLED;
  uint16_t randomNumber = 0x1234;

  // -------- Inits --------- //
  LED_DDR = 0xff;                    /* all LEDs configured for output */
  // ------ Event loop ------ //
  while (1) {
                                                            /* Go Left */
    for (i = 0; i < 8; i++) {
      LED_PORT |= (1 << i);                    /* turn on the i'th pin */
      _delay_ms(DELAYTIME);                                    /* wait */
    }
    for (i = 0; i < 8; i++) {
      LED_PORT &= ~(1 << i);                  /* turn off the i'th pin */
      _delay_ms(DELAYTIME);                                    /* wait */
    }
    _delay_ms(5 * DELAYTIME);                                 /* pause */

                                                           /* Go Right */
    for (i = 7; i < 255; i--) {
      LED_PORT |= (1 << i);                    /* turn on the i'th pin */
      _delay_ms(DELAYTIME);                                    /* wait */
    }
    for (i = 7; i < 255; i--) {
      LED_PORT &= ~(1 << i);                  /* turn off the i'th pin */
      _delay_ms(DELAYTIME);                                    /* wait */
    }
    _delay_ms(5 * DELAYTIME);                                 /* pause */

                                   /* Toggle "random" bits for a while */
    for (repetitions = 0; repetitions < 75; repetitions++) {
                                          /* "random" number generator */
      randomNumber = 2053 * randomNumber + 13849;
                                      /* low three bits from high byte */
      whichLED = (randomNumber >> 8) & 0b00000111;
      LED_PORT ^= (1 << whichLED);                   /* toggle our LED */
      _delay_ms(DELAYTIME);
    }
    LED_PORT = 0;                                      /* all LEDs off */
    _delay_ms(5 * DELAYTIME);                                 /* pause */

  }                                                  /* End event loop */
  return 0;                            /* This line is never reached */
}