77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    

    
    if ((cfg->reg & 0x0001) == 0)
        return 0;

    
    unsigned short priority = (cfg->reg >> 2) & 0x3;  

    if (priority == 3)    
        return 0;

    
    if (cfg->reg & 0xFFF0)     // anything above bit3 should be zero
        return 0;

    return 1;
}

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

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

    return 0;
}