77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    if (cfg->reg & (1U << 0) == 0) return 0;
    if (((cfg->reg >> 2) & 0b11) == 0b11) return 0;
    if (((cfg->reg >> 4) & ((1U << 12) - 1)) != 0) return 0;

    return 1;
}

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

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

    return 0;
}