gistfile1.sh

hads@bromine:~$ grep -A 10 ADC_REFSEL_enum /usr/local/share/avr8-gnu-toolchain-linux_x86_64/avr/include/avr/iox64d4.h 
typedef enum ADC_REFSEL_enum
{
    ADC_REFSEL_INT1V_gc = (0x00<<4),  /* Internal 1V */
    ADC_REFSEL_VCC_gc = (0x01<<4),  /* Internal VCC / 1.6 */
    ADC_REFSEL_AREFA_gc = (0x02<<4),  /* External reference on PORT A */
    ADC_REFSEL_AREFB_gc = (0x03<<4),  /* External reference on PORT B */
    ADC_REFSEL_VCCDIV2_gc = (0x04<<4),  /* Internal VCC / 2 */
} ADC_REFSEL_t;

/* Event channel input selection */
typedef enum ADC_EVSEL_enum