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FLASHING.md says how to take a newer version of the colleague's tree (copy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/NativeEnumerated_oer.c

@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>.
+ * All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include "asn_internal.h"
+#include "NativeEnumerated.h"
+
+static long
+asn__nativeenumerated_convert(const uint8_t *b, const uint8_t *end) {
+    unsigned long value;
+
+    /* Perform the sign initialization */
+    /* Actually value = -(*b >> 7); gains nothing, yet unreadable! */
+    if((*b >> 7)) {
+        value = (unsigned long)(-1);
+    } else {
+        value = 0;
+    }
+
+    /* Conversion engine */
+    for(; b < end; b++) {
+        value = (value << 8) | *b;
+    }
+
+    return value;
+}
+
+asn_dec_rval_t
+NativeEnumerated_decode_oer(const asn_codec_ctx_t *opt_codec_ctx,
+                            const asn_TYPE_descriptor_t *td,
+                            const asn_oer_constraints_t *constraints,
+                            void **nint_ptr, const void *ptr, size_t size) {
+    asn_dec_rval_t rval = {RC_OK, 0};
+    long *native = (long *)*nint_ptr;
+    const uint8_t *b = ptr;
+
+    (void)opt_codec_ctx;
+    (void)constraints;
+
+    if(size < 1) {
+        ASN__DECODE_STARVED;
+    }
+
+    if((*b & 0x80) == 0) {
+        /*
+         * X.696 (08/2015) #11.2 Short form for Enumerated.
+         */
+        if(!native) {
+            native = (long *)(*nint_ptr = CALLOC(1, sizeof(*native)));
+            if(!native) ASN__DECODE_FAILED;
+        }
+
+        *native = *b;
+        rval.consumed = 1;
+    } else {
+        /*
+         * X.696 (08/2015) #11.4 Long form for Enumerated.
+         */
+        size_t length = *b & 0x7f;
+        const uint8_t *bend;
+        long value;
+
+        if(length < 1 || length > sizeof(*native)) {
+            ASN__DECODE_FAILED;
+        }
+        if((1 + length) > size) {
+            ASN__DECODE_STARVED;
+        }
+        b++;
+        bend = b + length;
+
+        value = asn__nativeenumerated_convert(b, bend);
+        if(value < 0) {
+            const asn_INTEGER_specifics_t *specs =
+                (const asn_INTEGER_specifics_t *)td->specifics;
+            if(specs && specs->field_unsigned) {
+                ASN__DECODE_FAILED;
+            }
+        }
+
+        if(!native) {
+            native = (long *)(*nint_ptr = CALLOC(1, sizeof(*native)));
+            if(!native) ASN__DECODE_FAILED;
+        }
+
+        *native = value;
+
+        rval.consumed = (1 + length);
+    }
+
+    return rval;
+}
+
+/*
+ * Encode as Canonical OER.
+ */
+asn_enc_rval_t
+NativeEnumerated_encode_oer(const asn_TYPE_descriptor_t *td,
+                            const asn_oer_constraints_t *constraints,
+                            const void *sptr, asn_app_consume_bytes_f *cb,
+                            void *app_key) {
+    asn_enc_rval_t er = {0,0,0};
+    long native;
+
+    (void)constraints;
+
+    if(!sptr) ASN__ENCODE_FAILED;
+
+    native = *(const long *)sptr;
+
+    if(native >= 0 && native <= 127) {
+        /* #11.2 Short form */
+        uint8_t b = native;
+        er.encoded = 1;
+        if(cb(&b, er.encoded, app_key) < 0) {
+            ASN__ENCODE_FAILED;
+        }
+        ASN__ENCODED_OK(er);
+    } else {
+        /* #11.2 Long form */
+        uint8_t buf[1 + sizeof(native)];
+        uint8_t *b = &buf[sizeof(native)];  /* Last addressable */
+        long final_pattern = -1 * (native < 0);
+
+        for(;;) {
+            *b-- = native;
+            native >>= 8;
+            if(native == final_pattern) {
+                if(final_pattern) {
+                    if((b[1] & 0x80)) break;
+                } else {
+                    if(!(b[1] & 0x80)) break;
+                }
+            }
+        }
+        *b = 0x80 | (&buf[sizeof(native)] - b);
+        er.encoded = 1 + (&buf[sizeof(native)] - b);
+        if(cb(b, er.encoded, app_key) < 0) {
+            ASN__ENCODE_FAILED;
+        }
+        ASN__ENCODED_OK(er);
+    }
+}