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_result;
    adc_result.adc_reg = reg;
    
    uint16_t channel = (adc_result.adc_reg >> 12) & ((1 << 4) - 1);
    uint16_t adc_value = (adc_result.adc_reg >> 0) & ((1 << 12) - 1);
    
    printf("Channel: %u\n", channel);
    printf("ADC Value: %u", adc_value);
    return 0;
}

Solving Approach