Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/vanetza/asn1/support/REAL_xer.c

@@ -0,0 +1,103 @@
+/*
+ * 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 "REAL.h"
+
+asn_enc_rval_t
+REAL_encode_xer(const asn_TYPE_descriptor_t *td, const void *sptr, int ilevel,
+                enum xer_encoder_flags_e flags, asn_app_consume_bytes_f *cb,
+                void *app_key) {
+    const REAL_t *st = (const REAL_t *)sptr;
+    asn_enc_rval_t er = {0,0,0};
+    double d;
+
+    (void)ilevel;
+
+    if(!st || !st->buf || asn_REAL2double(st, &d))
+        ASN__ENCODE_FAILED;
+
+    er.encoded = REAL__dump(d, flags & XER_F_CANONICAL, cb, app_key);
+    if(er.encoded < 0) ASN__ENCODE_FAILED;
+
+    ASN__ENCODED_OK(er);
+}
+
+/*
+ * Decode the chunk of XML text encoding REAL.
+ */
+static enum xer_pbd_rval
+REAL__xer_body_decode(const asn_TYPE_descriptor_t *td, void *sptr,
+                      const void *chunk_buf, size_t chunk_size) {
+    REAL_t *st = (REAL_t *)sptr;
+    double value;
+    const char *xerdata = (const char *)chunk_buf;
+    char *endptr = 0;
+    char *b;
+
+    (void)td;
+
+    if(!chunk_size) return XPBD_BROKEN_ENCODING;
+
+    /*
+     * Decode an XMLSpecialRealValue: <MINUS-INFINITY>, etc.
+     */
+    if(xerdata[0] == 0x3c /* '<' */) {
+        size_t i;
+        for(i = 0; i < sizeof(specialRealValue) / sizeof(specialRealValue[0]); i++) {
+            struct specialRealValue_s *srv = &specialRealValue[i];
+            double dv;
+
+            if(srv->length != chunk_size
+            || memcmp(srv->string, chunk_buf, chunk_size))
+                continue;
+
+            /*
+             * It could've been done using
+             * (double)srv->dv / real_zero,
+             * but it summons fp exception on some platforms.
+             */
+            switch(srv->dv) {
+            case -1: dv = - INFINITY; break;
+            case 0: dv = NAN;	break;
+            case 1: dv = INFINITY;	break;
+            default: return XPBD_SYSTEM_FAILURE;
+            }
+
+            if(asn_double2REAL(st, dv))
+                return XPBD_SYSTEM_FAILURE;
+
+            return XPBD_BODY_CONSUMED;
+        }
+        ASN_DEBUG("Unknown XMLSpecialRealValue");
+        return XPBD_BROKEN_ENCODING;
+    }
+
+    /*
+     * Copy chunk into the nul-terminated string, and run strtod.
+     */
+    b = (char *)MALLOC(chunk_size + 1);
+    if(!b) return XPBD_SYSTEM_FAILURE;
+    memcpy(b, chunk_buf, chunk_size);
+    b[chunk_size] = 0;	/* nul-terminate */
+
+    value = strtod(b, &endptr);
+    FREEMEM(b);
+    if(endptr == b) return XPBD_BROKEN_ENCODING;
+
+    if(asn_double2REAL(st, value))
+        return XPBD_SYSTEM_FAILURE;
+
+    return XPBD_BODY_CONSUMED;
+}
+
+asn_dec_rval_t
+REAL_decode_xer(const asn_codec_ctx_t *opt_codec_ctx,
+                const asn_TYPE_descriptor_t *td, void **sptr,
+                const char *opt_mname, const void *buf_ptr, size_t size) {
+    return xer_decode_primitive(opt_codec_ctx, td,
+                                sptr, sizeof(REAL_t), opt_mname,
+                                buf_ptr, size, REAL__xer_body_decode);
+}