Validate Configuration Register Layout

Code

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    int flag = 1;
    if (cfg->reg & 1U == 0) flag = 0;
    else if (((cfg->reg & 0b1100)>>2)==0b11) flag = 0;
    else if ((cfg->reg & ~(0b1111)) != 0) flag = 0;
    return flag;
}

int main() {
    ConfigRegister cfg;
    scanf("%hx", &cfg.reg);

    int result = validate_config(&cfg);
    printf("%d", result);

    return 0;
}

Solving Approach