Merge pull request #84 from ddemidov/bin_data

[cpp][py] Expose sensor.bin_data attrbute

Author: WasabiFan

cpp/ev3dev.cpp

@@ -528,6 +528,45 @@ float sensor::float_value(unsigned index) const
   return value(index) * powf(10, -decimals());
 }
 
+//-----------------------------------------------------------------------------
+const std::vector<char>& sensor::bin_data() const
+{
+  using namespace std;
+
+  if (_path.empty())
+    throw system_error(make_error_code(errc::function_not_supported), "no device connected");
+
+  if (_bin_data.empty()) {
+    static const map<string, int> lookup_table {
+      {"u8",     1},
+      {"s8",     1},
+      {"u16",    2},
+      {"s16",    2},
+      {"s16_be", 2},
+      {"s32",    4},
+      {"float",  4}
+    };
+
+    int value_size = 1;
+
+    auto s = lookup_table.find(bin_data_format());
+    if (s != lookup_table.end())
+      value_size = s->second;
+
+    _bin_data.resize(num_values() * value_size);
+  }
+
+  static const string fname = _path + "bin_data";
+  ifstream &is = ifstream_open(fname);
+  if (is.is_open())
+  {
+    is.read(_bin_data.data(), _bin_data.size());
+    return _bin_data;
+  }
+
+  throw system_error(make_error_code(errc::no_such_device), fname);
+}
+
 //-----------------------------------------------------------------------------
 
 i2c_sensor::i2c_sensor(port_type port_) :

cpp/ev3dev.h

@@ -35,6 +35,8 @@
 #include <map>
 #include <set>
 #include <string>
+#include <vector>
+#include <algorithm>
 #include <functional>
 
 //-----------------------------------------------------------------------------
@@ -151,6 +153,35 @@ class sensor : protected device
   // Human-readable name of the connected sensor.
   std::string type_name() const;
 
+  // Bin Data Format: read-only
+  // Returns the format of the values in `bin_data` for the current mode.
+  // Possible values are:
+  //
+  //    - `u8`: Unsigned 8-bit integer (byte)
+  //    - `s8`: Signed 8-bit integer (sbyte)
+  //    - `u16`: Unsigned 16-bit integer (ushort)
+  //    - `s16`: Signed 16-bit integer (short)
+  //    - `s16_be`: Signed 16-bit integer, big endian
+  //    - `s32`: Signed 32-bit integer (int)
+  //    - `float`: IEEE 754 32-bit floating point (float)
+  std::string bin_data_format() const { return get_attr_string("bin_data_format"); };
+
+  // Bin Data: read-only
+  // Returns the unscaled raw values in the `value<N>` attributes as raw byte
+  // array. Use `bin_data_format`, `num_values` and the individual sensor
+  // documentation to determine how to interpret the data.
+  const std::vector<char>& bin_data() const;
+
+  // Bin Data: read-only
+  // Writes the unscaled raw values in the `value<N>` attributes into the
+  // user-provided struct/buffer.  Use `bin_data_format`, `num_values` and the
+  // individual sensor documentation to determine how to interpret the data.
+  template <class T>
+  void bin_data(T *buf) const {
+      bin_data(); // fills _bin_data
+      std::copy_n(_bin_data.data(), _bin_data.size(), static_cast<char*>(buf));
+  }
+
   //~autogen cpp_generic-get-set classes.sensor>currentClass
 
   // Command: write-only
@@ -210,6 +241,8 @@ class sensor : protected device
   sensor() {}
 
   bool connect(const std::map<std::string, std::set<std::string>>&) noexcept;
+
+  mutable std::vector<char> _bin_data;
 };
 
 //-----------------------------------------------------------------------------