77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    if((cfg->reg&1) == 1){
        if((cfg->reg & 0xC)>>2 != 3){
            if((cfg->reg & (~(0xF)))==0){
                return 1;
            }
        }
    }
    return 0;
}

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

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

    return 0;
}