77. Validate Configuration Register Layout

#include <stdio.h>

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    // Write logic using pointer access
    
    unsigned short val = cfg->reg;
    if(!(val % 2))              return 0;
    if((val & 0x0C) == 0x0C)    return 0;
    if(val & 0xfff0)            return 0;
    return 1;
}

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

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

    return 0;
}

make a local copy of reg and check with bitwise and operation with correct 1s.