77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    bool valid = true;
    if (cfg->reg > 0xF) {
        valid = false;
    }
    if ((cfg->reg >> 2) == 0x3) {
        valid = false;
    }
    if (!(cfg->reg & 1)) {
        valid = false;
    }
    return valid? 1:0;
}

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

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

    return 0;
}