Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/vanetza/asn1/support/asn_codecs.h

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2003-2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef	ASN_CODECS_H
+#define	ASN_CODECS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct asn_TYPE_descriptor_s;	/* Forward declaration */
+
+/*
+ * This structure defines a set of parameters that may be passed
+ * to every ASN.1 encoder or decoder function.
+ * WARNING: if max_stack_size member is set, and you are calling the
+ *   function pointers of the asn_TYPE_descriptor_t directly,
+ *   this structure must be ALLOCATED ON THE STACK!
+ *   If you can't always satisfy this requirement, use ber_decode(),
+ *   xer_decode() and uper_decode() functions instead.
+ */
+typedef struct asn_codec_ctx_s {
+	/*
+	 * Limit the decoder routines to use no (much) more stack than a given
+	 * number of bytes. Most of decoders are stack-based, and this
+	 * would protect against stack overflows if the number of nested
+	 * encodings is high.
+	 * The OCTET STRING, BIT STRING and ANY BER decoders are heap-based,
+	 * and are safe from this kind of overflow.
+	 * A value from getrlimit(RLIMIT_STACK) may be used to initialize
+	 * this variable. Be careful in multithreaded environments, as the
+	 * stack size is rather limited.
+	 */
+	size_t  max_stack_size; /* 0 disables stack bounds checking */
+	
+	/*
+	 * Decoder validation flags. Used by PER/UPER decoders to control
+	 * canonical vs basic decoding behavior.
+	 */
+	unsigned int uper_canonical:1;  /* Enable canonical UPER validation */
+	unsigned int uper_canonical_lenient:1;  /* Enable lenient canonical validation for interoperability */
+	
+	/*
+	 * Partial decoding support. When enabled, the decoder will preserve
+	 * partially decoded structures on failure instead of freeing them.
+	 * This allows inspection of what was successfully decoded before
+	 * the error occurred.
+	 */
+	unsigned int preserve_partial_decoding:1;
+} asn_codec_ctx_t;
+
+/*
+ * Type of the return value of the encoding functions (der_encode, xer_encode).
+ */
+typedef struct asn_enc_rval_s {
+	/*
+	 * Number of bytes encoded.
+	 * -1 indicates failure to encode the structure.
+	 * In this case, the members below this one are meaningful.
+	 */
+	ssize_t encoded;
+
+	/*
+	 * Members meaningful when (encoded == -1), for post mortem analysis.
+	 */
+
+	/* Type which cannot be encoded */
+	const struct asn_TYPE_descriptor_s *failed_type;
+
+	/* Pointer to the structure of that type */
+	const void *structure_ptr;
+} asn_enc_rval_t;
+#define	ASN__ENCODE_FAILED do {					\
+	asn_enc_rval_t tmp_error;				\
+	tmp_error.encoded = -1;					\
+	tmp_error.failed_type = td;				\
+	tmp_error.structure_ptr = sptr;				\
+	ASN_DEBUG("Failed to encode element %s", td ? td->name : "");	\
+	return tmp_error;					\
+} while(0)
+#define	ASN__ENCODED_OK(rval) do {				\
+	rval.structure_ptr = 0;					\
+	rval.failed_type = 0;					\
+	return rval;						\
+} while(0)
+
+/*
+ * Type of the return value of the decoding functions (ber_decode, xer_decode)
+ * 
+ * Please note that the number of consumed bytes is ALWAYS meaningful,
+ * even if code==RC_FAIL. This is to indicate the number of successfully
+ * decoded bytes, hence providing a possibility to fail with more diagnostics
+ * (i.e., print the offending remainder of the buffer).
+ */
+enum asn_dec_rval_code_e {
+	RC_OK,		/* Decoded successfully */
+	RC_WMORE,	/* More data expected, call again */
+	RC_FAIL		/* Failure to decode data */
+};
+typedef struct asn_dec_rval_s {
+	enum asn_dec_rval_code_e code;	/* Result code */
+	size_t consumed;		/* Number of bytes consumed */
+} asn_dec_rval_t;
+#define	ASN__DECODE_FAILED do {					\
+	asn_dec_rval_t tmp_error;				\
+	tmp_error.code = RC_FAIL;				\
+	tmp_error.consumed = 0;					\
+	ASN_DEBUG("Failed to decode element %s", td ? td->name : "");	\
+	return tmp_error;					\
+} while(0)
+#define	ASN__DECODE_STARVED do {				\
+	asn_dec_rval_t tmp_error;				\
+	tmp_error.code = RC_WMORE;				\
+	tmp_error.consumed = 0;					\
+	return tmp_error;					\
+} while(0)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* ASN_CODECS_H */