add common lib
diff --git a/libasn1common/asn1_ref.h b/libasn1common/asn1_ref.h
new file mode 100644
index 0000000..dbc8f87
--- /dev/null
+++ b/libasn1common/asn1_ref.h
@@ -0,0 +1,80 @@
+/*
+ * Generic reference to the yet unknown type defined elsewhere.
+ */
+#ifndef ASN1_REFERENCE_H
+#define ASN1_REFERENCE_H
+
+struct asn1p_module_s;
+
+typedef struct asn1p_ref_s {
+
+ /*
+ * A set of reference name components.
+ * A reference name consists of several components separated by dots:
+ * "OBJECT-CLASS.&Algorithm.&id"
+ */
+ struct asn1p_ref_component_s {
+ enum asn1p_ref_lex_type_e {
+ RLT_UNKNOWN, /* Invalid? */
+ /*
+ * Object class reference "OCLASS1",
+ * type reference "Type1",
+ * value reference "id",
+ * type field reference "&Type1",
+ * value field reference "&id",
+ * "OBJECT-CLASS"
+ */
+ RLT_CAPITALS,
+ RLT_Uppercase,
+ RLT_lowercase,
+ RLT_AmpUppercase,
+ RLT_Amplowercase,
+ RLT_Atlowercase,
+ RLT_AtDotlowercase,
+ RLT_MAX
+ } lex_type; /* Inferred lexical type of the identifier */
+ char *name; /* An identifier */
+ } *components;
+
+ size_t comp_count; /* Number of the components in the reference name. */
+ size_t comp_size; /* Number of allocated structures */
+
+ struct asn1p_module_s *module; /* Defined in module */
+ int _lineno; /* Number of line in the file */
+} asn1p_ref_t;
+
+/*
+ * Constructor and destructor.
+ */
+asn1p_ref_t *asn1p_ref_new(int _lineno, struct asn1p_module_s *mod);
+void asn1p_ref_free(asn1p_ref_t *);
+
+asn1p_ref_t *asn1p_ref_clone(asn1p_ref_t *ref);
+
+void asn1p_ref_set_source(asn1p_ref_t *, struct asn1p_module_s *module,
+ int lineno);
+
+
+/*
+ * Lexicographically compare references.
+ */
+int asn1p_ref_compare(const asn1p_ref_t *, const asn1p_ref_t *);
+
+/*
+ * Return a pointer to a statically allocated buffer representing the
+ * complete reference.
+ */
+const char *asn1p_ref_string(const asn1p_ref_t *);
+
+/*
+ * Add a new reference component to the existing reference structure.
+ *
+ * RETURN VALUES:
+ * 0: All clear.
+ * -1/EINVAL: Invalid arguments
+ * -1/ENOMEM: Memory allocation failed
+ */
+int asn1p_ref_add_component(asn1p_ref_t *,
+ const char *name, enum asn1p_ref_lex_type_e);
+
+#endif /* ASN1_REFERENCE_H */