add OER encoder helpers
diff --git a/skeletons/oer_encoder.c b/skeletons/oer_encoder.c
new file mode 100644
index 0000000..8a34815
--- /dev/null
+++ b/skeletons/oer_encoder.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include <asn_internal.h>
+
+/*
+ * The OER encoder of any type.
+ */
+asn_enc_rval_t
+oer_encode(asn_TYPE_descriptor_t *type_descriptor, void *struct_ptr,
+ asn_app_consume_bytes_f *consume_bytes, void *app_key) {
+
+ ASN_DEBUG("OER encoder invoked for %s",
+ type_descriptor->name);
+
+ /*
+ * Invoke type-specific encoder.
+ */
+ return type_descriptor->oer_encoder(type_descriptor, 0,
+ struct_ptr, /* Pointer to the destination structure */
+ consume_bytes, app_key);
+}
+
+/*
+ * Argument type and callback necessary for oer_encode_to_buffer().
+ */
+typedef struct enc_to_buf_arg {
+ void *buffer;
+ size_t left;
+} enc_to_buf_arg;
+static int encode_to_buffer_cb(const void *buffer, size_t size, void *key) {
+ enc_to_buf_arg *arg = (enc_to_buf_arg *)key;
+
+ if(arg->left < size)
+ return -1; /* Data exceeds the available buffer size */
+
+ memcpy(arg->buffer, buffer, size);
+ arg->buffer = ((char *)arg->buffer) + size;
+ arg->left -= size;
+
+ return 0;
+}
+
+/*
+ * A variant of the oer_encode() which encodes the data into the provided buffer
+ */
+asn_enc_rval_t
+oer_encode_to_buffer(struct asn_TYPE_descriptor_s *type_descriptor,
+ void *struct_ptr, /* Structure to be encoded */
+ void *buffer, /* Pre-allocated buffer */
+ size_t buffer_size /* Initial buffer size (maximum) */
+ ) {
+ enc_to_buf_arg arg;
+ asn_enc_rval_t ec;
+
+ arg.buffer = buffer;
+ arg.left = buffer_size;
+
+ ec = type_descriptor->oer_encoder(
+ type_descriptor, 0,
+ struct_ptr, /* Pointer to the destination structure */
+ encode_to_buffer_cb, &arg);
+ if(ec.encoded != -1) {
+ assert(ec.encoded == (ssize_t)(buffer_size - arg.left));
+ /* Return the encoded contents size */
+ }
+ return ec;
+}