Initial commit

src/config.cpp

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: MIT
+// SPDX-FileCopyrightText: 2026 Martino Ferrari
+
+#include "config.hpp"
+
+#include <cstdio>
+#include <cstdlib>
+#include <stdexcept>
+#include <string>
+
+namespace udpscope {
+namespace {
+
+[[noreturn]] void fail(const std::string& what) { throw std::runtime_error(what); }
+
+/// `--name=value` / `--name value`; returns the value and advances `i` past both
+/// spellings. `argv[i]` must start with `--name`.
+std::string value_of(int argc, char** argv, int& i, const char* name) {
+  const std::string arg = argv[i];
+  const std::string prefix = std::string(name) + "=";
+  if (arg.rfind(prefix, 0) == 0) return arg.substr(prefix.size());
+  if (i + 1 >= argc) fail(std::string("missing value for ") + name);
+  return argv[++i];
+}
+
+double parse_double(const char* name, const std::string& v) {
+  try {
+    std::size_t used = 0;
+    const double d = std::stod(v, &used);
+    if (used != v.size()) fail(std::string("not a number: ") + name + " " + v);
+    return d;
+  } catch (const std::exception&) {
+    fail(std::string("not a number: ") + name + " " + v);
+  }
+}
+
+}  // namespace
+
+void print_usage(std::FILE* out, const char* argv0) {
+  std::fprintf(out,
+               "usage: %s --server ADDR --port PORT [options]\n"
+               "\n"
+               "  --server ADDR        stream source IPv4 address (default 127.0.0.1)\n"
+               "  --port PORT          UDP port (unicast) or TCP port (multicast) (default 8000)\n"
+               "  --multicast GROUP    join GROUP for DATA instead of unicast\n"
+               "  --interface ADDR     local IPv4 of the interface to join on\n"
+               "  --buffer-mb MB       size of each of the two sample buffers (default 200)\n"
+               "  --max-window SEC     largest time window the toolbar offers (default 600)\n"
+               "  --holdoff SEC        default trigger hold-off (default 0.010)\n"
+               "  --recv-buffer BYTES  SO_RCVBUF for the receiver socket (default 8388608)\n"
+               "  --plots N            initial number of stacked plots, 1..4 (default 1)\n"
+               "  -h, --help           this text\n",
+               argv0);
+}
+
+Config parse_args(int argc, char** argv) {
+  Config c;
+  for (int i = 1; i < argc; ++i) {
+    const std::string a = argv[i];
+    if (a == "-h" || a == "--help") {
+      print_usage(stdout, argv[0]);
+      std::exit(0);
+    } else if (a == "--server" || a.rfind("--server=", 0) == 0) {
+      c.server = value_of(argc, argv, i, "--server");
+    } else if (a == "--port" || a.rfind("--port=", 0) == 0) {
+      const std::string v = value_of(argc, argv, i, "--port");
+      const long p = std::strtol(v.c_str(), nullptr, 10);
+      if (p <= 0 || p > 65535) fail("port out of range: " + v);
+      c.port = static_cast<std::uint16_t>(p);
+    } else if (a == "--multicast" || a.rfind("--multicast=", 0) == 0) {
+      c.multicast = value_of(argc, argv, i, "--multicast");
+    } else if (a == "--interface" || a.rfind("--interface=", 0) == 0) {
+      c.interface_addr = value_of(argc, argv, i, "--interface");
+    } else if (a == "--buffer-mb" || a.rfind("--buffer-mb=", 0) == 0) {
+      c.buffer_mb = parse_double("--buffer-mb", value_of(argc, argv, i, "--buffer-mb"));
+      if (c.buffer_mb < 1.0) fail("--buffer-mb must be at least 1");
+    } else if (a == "--max-window" || a.rfind("--max-window=", 0) == 0) {
+      c.max_window_s = parse_double("--max-window", value_of(argc, argv, i, "--max-window"));
+      if (c.max_window_s <= 0.0) fail("--max-window must be positive");
+    } else if (a == "--holdoff" || a.rfind("--holdoff=", 0) == 0) {
+      c.trigger_holdoff_s = parse_double("--holdoff", value_of(argc, argv, i, "--holdoff"));
+      if (c.trigger_holdoff_s < 0.0) fail("--holdoff must not be negative");
+    } else if (a == "--recv-buffer" || a.rfind("--recv-buffer=", 0) == 0) {
+      const std::string v = value_of(argc, argv, i, "--recv-buffer");
+      const long n = std::strtol(v.c_str(), nullptr, 10);
+      if (n <= 0) fail("--recv-buffer must be positive: " + v);
+      c.recv_buffer_bytes = static_cast<int>(n);
+    } else if (a == "--plots" || a.rfind("--plots=", 0) == 0) {
+      const std::string v = value_of(argc, argv, i, "--plots");
+      const long n = std::strtol(v.c_str(), nullptr, 10);
+      if (n < 1 || n > 4) fail("--plots must be 1..4: " + v);
+      c.plots = static_cast<int>(n);
+    } else {
+      fail("unknown argument: " + a);
+    }
+  }
+  return c;
+}
+
+}  // namespace udpscope