Validate Configuration Register Layout

Code

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    
    unsigned short reg = cfg->reg;

    if(!cfg)
        return 0;

    if(!(reg & 0x01))
        return 0;

     if(((reg >> 2) & 0x03) == 3)
        return 0;

     if(reg >> 4)
        return 0;

    return 1;
    
#if 0
    unsigned short val = cfg->reg;

    int enable = val & 0x0001;
    int priority = (val >> 2) & 0x03;
    int reserved_clear = (val & 0xFFF0) == 0;

    return (enable && priority != 0x03 && reserved_clear);
#endif
}

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

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

    return 0;
}

Solving Approach