libbsdl: scaffold + working BSDL parser (struct + JSON, C ABI)

Standalone LGPL-2.1 parser for BSDL (IEEE 1149.1), shared by essim and
bs_explorer. The parser is ported from the Viveris JTAG Core loader,
decoupled from jtag_core, and extended with two extractions the original
lacks:
  - PIN_MAP_STRING -> per-port physical package pin, scalar and vector;
  - TAP_SCAN_*     -> TAP signal roles (TDI/TDO/TMS/TCK/TRST).

Exposes a stable C ABI (bsdl_parse_file/buffer -> bsdl_t, bsdl_to_json)
with a dependency-free JSON serializer and a bsdl2json CLI. CMake builds a
versioned shared library with install/export rules for find_package(bsdl).

Verified against m2gl010t, xcku040 and xcku15p (100% pin mapping, correct
IDCODEs and TAP roles); api and parse regression tests pass, clean build.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tools/bsdl2json.c

@@ -0,0 +1,77 @@
+/*
+ * bsdl2json - parse a BSDL file and print the model as JSON on stdout.
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * Thin frontend over libbsdl. essim invokes this out-of-process; bs_explorer
+ * links the library directly and uses the struct instead.
+ */
+#include <stdio.h>
+#include <string.h>
+
+#include "bsdl/bsdl.h"
+
+static void log_cb(bsdl_log_level_t level, const char* msg, void* user)
+{
+    static const char* const names[] = { "ERROR", "WARN", "INFO", "DEBUG" };
+    (void)user;
+    fprintf(stderr, "[bsdl:%s] %s\n", names[level], msg);
+}
+
+static void usage(const char* argv0)
+{
+    fprintf(stderr,
+        "libbsdl %s\n"
+        "usage: %s [--quiet] <file.bsd>\n"
+        "  prints the parsed BSDL model as JSON on stdout\n",
+        bsdl_version(), argv0);
+}
+
+int main(int argc, char** argv)
+{
+    bsdl_opts_t opts;
+    const char* path = NULL;
+    int quiet = 0;
+    int i;
+    bsdl_t* model;
+    char* json;
+
+    for (i = 1; i < argc; i++) {
+        if (!strcmp(argv[i], "--quiet") || !strcmp(argv[i], "-q")) {
+            quiet = 1;
+        } else if (!strcmp(argv[i], "--help") || !strcmp(argv[i], "-h")) {
+            usage(argv[0]);
+            return 0;
+        } else if (argv[i][0] == '-') {
+            fprintf(stderr, "unknown option: %s\n", argv[i]);
+            usage(argv[0]);
+            return 2;
+        } else {
+            path = argv[i];
+        }
+    }
+
+    if (!path) {
+        usage(argv[0]);
+        return 2;
+    }
+
+    bsdl_opts_default(&opts);
+    if (!quiet)
+        opts.log = log_cb;
+
+    model = bsdl_parse_file(path, &opts);
+    if (!model) {
+        fprintf(stderr, "error: failed to parse %s\n", path);
+        return 1;
+    }
+
+    json = bsdl_to_json(model);
+    if (json) {
+        fputs(json, stdout);
+        fputc('\n', stdout);
+        bsdl_string_free(json);
+    }
+
+    bsdl_free(model);
+    return 0;
+}