Decode ADC Result Using Union Bitfields

Code

#include <stdio.h>
#include <stdint.h>

typedef union {
    struct {
        uint16_t adc_value : 12;
        uint16_t channel   : 4;
    };
    uint16_t adc_reg;
} ADC_Result;

int main() {
    uint16_t reg;
    scanf("%hx", &reg);

    // Fill union and print channel and adc_value
    ADC_Result *adc;

    adc->adc_value = reg & 0xFFF;
    adc->channel = (reg >> 12) & 0xF;

    printf("Channel: %d\n", adc->channel);
    printf("ADC Value: %d\n", adc->adc_value);
    
    return 0;
}

Solving Approach