How to get key usage values from X509 cert?

I need to retrieve information from x509 cert to verify Key usage. For example I need to make sure certificate can be used for digital signing (80).

It can be printed out by the following code piece, but i actually want to verify if certificate has a specific property. What i need is a method like boolean certHasAbility(X509 * cert, int purpose );, where purpose can be DigitalSignature(80) or Key Encipherment(20).

STACK_OF(X509_EXTENSION) *ext_list;

ext_list = cert->cert_info->extensions;
outbio  = BIO_new_fp(stdout, BIO_NOCLOSE);

if(sk_X509_EXTENSION_num(ext_list) <= 0)
    return 1;

for (int i=0; i<sk_X509_EXTENSION_num(ext_list); i++) {
    ASN1_OBJECT *obj;
    X509_EXTENSION *ext;

    ext = sk_X509_EXTENSION_value(ext_list, i);

    obj = X509_EXTENSION_get_object(ext);
    BIO_printf(outbio, "\n");
    BIO_printf(outbio, "Object %.2d: ", i);
    i2a_ASN1_OBJECT(outbio, obj);
    BIO_printf(outbio, "\n");
    X509V3_EXT_print(outbio, ext, NULL, NULL);
    BIO_printf(outbio, "\n");
}