Validate Configuration Register Layout

Code

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    if(!cfg->reg & 1) goto l1;
    else if((cfg->reg>>2)&1 & (cfg->reg>>3)&1) goto l1;
    else{
        for(int i=4;i<16;i++){
            if((cfg->reg>>i)&1) goto l1;
        }
    }
        return 1;
l1:    return 0;
}

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

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

    return 0;
}

Solving Approach