diff --git a/src/rspro/asn_codecs_prim.c b/src/rspro/asn_codecs_prim.c
new file mode 100644
index 0000000..8e604a4
--- /dev/null
+++ b/src/rspro/asn_codecs_prim.c
@@ -0,0 +1,312 @@
+/*-
+ * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include <asn_internal.h>
+#include <asn_codecs_prim.h>
+#include <errno.h>
+
+/*
+ * Decode an always-primitive type.
+ */
+asn_dec_rval_t
+ber_decode_primitive(asn_codec_ctx_t *opt_codec_ctx,
+	asn_TYPE_descriptor_t *td,
+	void **sptr, const void *buf_ptr, size_t size, int tag_mode) {
+	ASN__PRIMITIVE_TYPE_t *st = (ASN__PRIMITIVE_TYPE_t *)*sptr;
+	asn_dec_rval_t rval;
+	ber_tlv_len_t length = 0; // =0 to avoid [incorrect] warning.
+
+	/*
+	 * If the structure is not there, allocate it.
+	 */
+	if(st == NULL) {
+		st = (ASN__PRIMITIVE_TYPE_t *)CALLOC(1, sizeof(*st));
+		if(st == NULL) _ASN_DECODE_FAILED;
+		*sptr = (void *)st;
+	}
+
+	ASN_DEBUG("Decoding %s as plain primitive (tm=%d)",
+		td->name, tag_mode);
+
+	/*
+	 * Check tags and extract value length.
+	 */
+	rval = ber_check_tags(opt_codec_ctx, td, 0, buf_ptr, size,
+			tag_mode, 0, &length, 0);
+	if(rval.code != RC_OK)
+		return rval;
+
+	ASN_DEBUG("%s length is %d bytes", td->name, (int)length);
+
+	/*
+	 * Make sure we have this length.
+	 */
+	buf_ptr = ((const char *)buf_ptr) + rval.consumed;
+	size -= rval.consumed;
+	if(length > (ber_tlv_len_t)size) {
+		rval.code = RC_WMORE;
+		rval.consumed = 0;
+		return rval;
+	}
+
+	st->size = (int)length;
+	/* The following better be optimized away. */
+	if(sizeof(st->size) != sizeof(length)
+			&& (ber_tlv_len_t)st->size != length) {
+		st->size = 0;
+		_ASN_DECODE_FAILED;
+	}
+
+	st->buf = (uint8_t *)MALLOC(length + 1);
+	if(!st->buf) {
+		st->size = 0;
+		_ASN_DECODE_FAILED;
+	}
+
+	memcpy(st->buf, buf_ptr, length);
+	st->buf[length] = '\0';		/* Just in case */
+
+	rval.code = RC_OK;
+	rval.consumed += length;
+
+	ASN_DEBUG("Took %ld/%ld bytes to encode %s",
+		(long)rval.consumed,
+		(long)length, td->name);
+
+	return rval;
+}
+
+/*
+ * Encode an always-primitive type using DER.
+ */
+asn_enc_rval_t
+der_encode_primitive(asn_TYPE_descriptor_t *td, void *sptr,
+	int tag_mode, ber_tlv_tag_t tag,
+	asn_app_consume_bytes_f *cb, void *app_key) {
+	asn_enc_rval_t erval;
+	ASN__PRIMITIVE_TYPE_t *st = (ASN__PRIMITIVE_TYPE_t *)sptr;
+
+	ASN_DEBUG("%s %s as a primitive type (tm=%d)",
+		cb?"Encoding":"Estimating", td->name, tag_mode);
+
+	erval.encoded = der_write_tags(td, st->size, tag_mode, 0, tag,
+		cb, app_key);
+	ASN_DEBUG("%s wrote tags %d", td->name, (int)erval.encoded);
+	if(erval.encoded == -1) {
+		erval.failed_type = td;
+		erval.structure_ptr = sptr;
+		return erval;
+	}
+
+	if(cb && st->buf) {
+		if(cb(st->buf, st->size, app_key) < 0) {
+			erval.encoded = -1;
+			erval.failed_type = td;
+			erval.structure_ptr = sptr;
+			return erval;
+		}
+	} else {
+		assert(st->buf || st->size == 0);
+	}
+
+	erval.encoded += st->size;
+	_ASN_ENCODED_OK(erval);
+}
+
+void
+ASN__PRIMITIVE_TYPE_free(asn_TYPE_descriptor_t *td, void *sptr,
+		int contents_only) {
+	ASN__PRIMITIVE_TYPE_t *st = (ASN__PRIMITIVE_TYPE_t *)sptr;
+
+	if(!td || !sptr)
+		return;
+
+	ASN_DEBUG("Freeing %s as a primitive type", td->name);
+
+	if(st->buf)
+		FREEMEM(st->buf);
+
+	if(!contents_only)
+		FREEMEM(st);
+}
+
+
+/*
+ * Local internal type passed around as an argument.
+ */
+struct xdp_arg_s {
+	asn_TYPE_descriptor_t *type_descriptor;
+	void *struct_key;
+	xer_primitive_body_decoder_f *prim_body_decoder;
+	int decoded_something;
+	int want_more;
+};
+
+/*
+ * Since some kinds of primitive values can be encoded using value-specific
+ * tags (<MINUS-INFINITY>, <enum-element>, etc), the primitive decoder must
+ * be supplied with such tags to parse them as needed.
+ */
+static int
+xer_decode__unexpected_tag(void *key, const void *chunk_buf, size_t chunk_size) {
+	struct xdp_arg_s *arg = (struct xdp_arg_s *)key;
+	enum xer_pbd_rval bret;
+
+	/*
+	 * The chunk_buf is guaranteed to start at '<'.
+	 */
+	assert(chunk_size && ((const char *)chunk_buf)[0] == 0x3c);
+
+	/*
+	 * Decoding was performed once already. Prohibit doing it again.
+	 */
+	if(arg->decoded_something)
+		return -1;
+
+	bret = arg->prim_body_decoder(arg->type_descriptor,
+		arg->struct_key, chunk_buf, chunk_size);
+	switch(bret) {
+	case XPBD_SYSTEM_FAILURE:
+	case XPBD_DECODER_LIMIT:
+	case XPBD_BROKEN_ENCODING:
+		break;
+	case XPBD_BODY_CONSUMED:
+		/* Tag decoded successfully */
+		arg->decoded_something = 1;
+		/* Fall through */
+	case XPBD_NOT_BODY_IGNORE:	/* Safe to proceed further */
+		return 0;
+	}
+
+	return -1;
+}
+
+static ssize_t
+xer_decode__primitive_body(void *key, const void *chunk_buf, size_t chunk_size, int have_more) {
+	struct xdp_arg_s *arg = (struct xdp_arg_s *)key;
+	enum xer_pbd_rval bret;
+	size_t lead_wsp_size;
+
+	if(arg->decoded_something) {
+		if(xer_whitespace_span(chunk_buf, chunk_size) == chunk_size) {
+			/*
+			 * Example:
+			 * "<INTEGER>123<!--/--> </INTEGER>"
+			 *                      ^- chunk_buf position.
+			 */
+			return chunk_size;
+		}
+		/*
+		 * Decoding was done once already. Prohibit doing it again.
+		 */
+		return -1;
+	}
+
+	if(!have_more) {
+		/*
+		 * If we've received something like "1", we can't really
+		 * tell whether it is really `1` or `123`, until we know
+		 * that there is no more data coming.
+		 * The have_more argument will be set to 1 once something
+		 * like this is available to the caller of this callback:
+		 * "1<tag_start..."
+		 */
+		arg->want_more = 1;
+		return -1;
+	}
+
+	lead_wsp_size = xer_whitespace_span(chunk_buf, chunk_size);
+	chunk_buf = (const char *)chunk_buf + lead_wsp_size;
+	chunk_size -= lead_wsp_size;
+
+	bret = arg->prim_body_decoder(arg->type_descriptor,
+		arg->struct_key, chunk_buf, chunk_size);
+	switch(bret) {
+	case XPBD_SYSTEM_FAILURE:
+	case XPBD_DECODER_LIMIT:
+	case XPBD_BROKEN_ENCODING:
+		break;
+	case XPBD_BODY_CONSUMED:
+		/* Tag decoded successfully */
+		arg->decoded_something = 1;
+		/* Fall through */
+	case XPBD_NOT_BODY_IGNORE:	/* Safe to proceed further */
+		return lead_wsp_size + chunk_size;
+	}
+
+	return -1;
+}
+
+
+asn_dec_rval_t
+xer_decode_primitive(asn_codec_ctx_t *opt_codec_ctx,
+	asn_TYPE_descriptor_t *td,
+	void **sptr,
+	size_t struct_size,
+	const char *opt_mname,
+	const void *buf_ptr, size_t size,
+	xer_primitive_body_decoder_f *prim_body_decoder
+) {
+	const char *xml_tag = opt_mname ? opt_mname : td->xml_tag;
+	asn_struct_ctx_t s_ctx;
+	struct xdp_arg_s s_arg;
+	asn_dec_rval_t rc;
+
+	/*
+	 * Create the structure if does not exist.
+	 */
+	if(!*sptr) {
+		*sptr = CALLOC(1, struct_size);
+		if(!*sptr) _ASN_DECODE_FAILED;
+	}
+
+	memset(&s_ctx, 0, sizeof(s_ctx));
+	s_arg.type_descriptor = td;
+	s_arg.struct_key = *sptr;
+	s_arg.prim_body_decoder = prim_body_decoder;
+	s_arg.decoded_something = 0;
+	s_arg.want_more = 0;
+
+	rc = xer_decode_general(opt_codec_ctx, &s_ctx, &s_arg,
+		xml_tag, buf_ptr, size,
+		xer_decode__unexpected_tag, xer_decode__primitive_body);
+	switch(rc.code) {
+	case RC_OK:
+		if(!s_arg.decoded_something) {
+			char ch;
+			ASN_DEBUG("Primitive body is not recognized, "
+				"supplying empty one");
+			/*
+			 * Decoding opportunity has come and gone.
+			 * Where's the result?
+			 * Try to feed with empty body, see if it eats it.
+			 */
+			if(prim_body_decoder(s_arg.type_descriptor,
+				s_arg.struct_key, &ch, 0)
+					!= XPBD_BODY_CONSUMED) {
+				/*
+				 * This decoder does not like empty stuff.
+				 */
+				_ASN_DECODE_FAILED;
+			}
+		}
+		break;
+	case RC_WMORE:
+		/*
+		 * Redo the whole thing later.
+		 * We don't have a context to save intermediate parsing state.
+		 */
+		rc.consumed = 0;
+		break;
+	case RC_FAIL:
+		rc.consumed = 0;
+		if(s_arg.want_more)
+			rc.code = RC_WMORE;
+		else
+			_ASN_DECODE_FAILED;
+		break;
+	}
+	return rc;
+}
+