source: normalise UDPS signal dimensions in to_info; comment tidy

src/acquisition.cpp

@@ -366,8 +366,8 @@ std::uint32_t Acquisition::build_stamps(const Frame& frame, int time_signal,
   if (time_source_ != 2 && time_signal >= 0 &&
       time_signal < static_cast<int>(frame.num_signals)) {
     const SignalInfo& ts = frame.signals[time_signal];
-    // How the client indexes a signal's values depends on its shape
+    // How a frame indexes a signal's values depends on its shape
-    // (`udps_frame_value`): a scalar carries one value per batched cycle, so the
+    // (`Frame::value`): a scalar carries one value per batched cycle, so the
     // stamp of sample k is (sample=k, elem=0); a multi-element signal carries one
     // *sample* of `elements` values per packet, so the stamp of sample k is
     // (sample=0, elem=k). Passing the scalar form for both is why FULL_ARRAY time
@@ -966,7 +966,7 @@ void Acquisition::on_data(const Frame& frame) {
       const double raw =
           ch.elements > 1
               ? frame.value(static_cast<std::uint32_t>(ch.signal), 0,
-                                 std::min<std::uint32_t>(k, ch.elements - 1))
+                            std::min<std::uint32_t>(k, ch.elements - 1))
               : frame.value(static_cast<std::uint32_t>(ch.signal), k, 0);
       // Every sample is read and accumulated even when only one in `period` is stored:
       // that is the whole point of the filter. Skipping the read -- which is what the
@@ -1202,10 +1202,10 @@ void Acquisition::backfill_from(const Frame& frame, const Partition& part,
         const double raw =
             channels[i].elements > 1
                 ? frame.value(static_cast<std::uint32_t>(channels[i].signal), 0,
-                                   std::min<std::uint32_t>(static_cast<std::uint32_t>(k),
+                              std::min<std::uint32_t>(static_cast<std::uint32_t>(k),
-                                                           channels[i].elements - 1))
+                                                      channels[i].elements - 1))
                 : frame.value(static_cast<std::uint32_t>(channels[i].signal),
-                                   static_cast<std::uint32_t>(k), 0);
+                              static_cast<std::uint32_t>(k), 0);
         acc += raw * channels[i].gain + channels[i].offset;
       }
       const f32 value = static_cast<f32>(acc / double(period));

src/acquisition.hpp

@@ -31,8 +31,8 @@ class Acquisition : private SourceSink {
   Acquisition(const Acquisition&) = delete;
   Acquisition& operator=(const Acquisition&) = delete;
 
-  /// Opens the client (no socket until the first poll) and starts the thread.
+  /// Opens the source (no socket until the first poll) and starts the thread.
-  /// Throws std::runtime_error when the client cannot be created.
+  /// Throws std::runtime_error when the source cannot be created.
   void start();
   /// Stops the thread and destroys the client. Idempotent.
   void stop();

src/source/udps_source.cpp

@@ -19,8 +19,17 @@ SignalInfo to_info(const udps_signal_t& s) {
   info.unit = s.unit;
   info.type_code = s.type_code;
   info.quant_type = s.quant_type;
-  info.rows = s.num_rows;
+  // Store the effective dimensions `udps_signal_num_elements` uses, so `SignalInfo::elements()`
-  info.cols = s.num_cols;
+  // (rows * cols) gives the same count for any CONFIG, hostile or odd ones included: a zero
+  // dimension means 1 on its own (rows 0, cols 5 is 5 elements), and the product is clamped to
+  // UDPS_MAX_ELEMENTS, which also keeps rows * cols from overflowing uint32.
+  std::uint64_t rows = s.num_rows == 0 ? 1u : s.num_rows;
+  std::uint64_t cols = s.num_cols == 0 ? 1u : s.num_cols;
+  if (rows > UDPS_MAX_ELEMENTS) rows = UDPS_MAX_ELEMENTS;
+  if (cols > UDPS_MAX_ELEMENTS) cols = UDPS_MAX_ELEMENTS;
+  if (rows * cols > UDPS_MAX_ELEMENTS) cols = UDPS_MAX_ELEMENTS / rows;
+  info.rows = static_cast<std::uint32_t>(rows);
+  info.cols = static_cast<std::uint32_t>(cols);
   info.range_min = s.range_min;
   info.range_max = s.range_max;
   info.time_mode = s.time_mode;