--- /dev/null
+/*
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef OER_SUPPORT_H
+#define OER_SUPPORT_H
+
+#include <asn_system.h> /* Platform-specific types */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Pre-computed OER constraints.
+ */
+typedef struct asn_oer_constraint_number_s {
+ unsigned width; /* ±8,4,2,1 fixed bytes */
+ unsigned positive; /* 1 for unsigned number, 0 for signed */
+} asn_oer_constraint_number_t;
+typedef struct asn_oer_constraints_s {
+ asn_oer_constraint_number_t value;
+ ssize_t size; /* -1 (no constraint) or >= 0 */
+} asn_oer_constraints_t;
+
+
+/*
+ * Fetch the length determinant (X.696 (08/2015), #8.6) into *len_r.
+ * RETURN VALUES:
+ * 0: More data expected than bufptr contains.
+ * -1: Fatal error deciphering length.
+ * >0: Number of bytes used from bufptr.
+ */
+ssize_t oer_fetch_length(const void *bufptr, size_t size, size_t *len_r);
+
+/*
+ * Serialize OER length. Returns the number of bytes serialized
+ * or -1 if a given callback returned with negative result.
+ */
+ssize_t oer_serialize_length(size_t length, asn_app_consume_bytes_f *cb, void *app_key);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OER_SUPPORT_H */