Validate Configuration Register Layout

Code

#include <stdio.h>

#define INVALID_PR (0x11)

#define BIT_EN  0
#define BIT_MOD 1
#define BIT_PR  2
#define BIT_RSV 4

#define MSK_EN  (1 << BIT_EN)
#define MSK_MOD (1 << BIT_MOD)
#define MSK_PR  ((1 << (BIT_PR + 1)) | (1 << BIT_PR))
#define MSK_RSV (~(MSK_EN | MSK_MOD | MSK_PR))

typedef struct {
    unsigned short reg;
} ConfigRegister;

int validate_config(ConfigRegister *cfg) {
    if ( cfg->reg & MSK_EN                            &&
        (cfg->reg & MSK_PR)  >> BIT_PR  != INVALID_PR &&
        (cfg->reg & MSK_RSV) >> BIT_RSV ==          0   )
        return 1;

    return 0;
}

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

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

    return 0;
}

Solving Approach