✨ noise command.

doc/guide/signals.rst

@@ -39,3 +39,13 @@ To generate a sine, we can use the ``sine`` command.
 
    # sine signal with a frequency of 440 and an amplitude of 1
    [sine 440 1]
+
+
+Noise
+^^^^^
+
+The noise command generate uniform random frames.
+
+.. code-block::
+
+   [noise]

lib/CMakeLists.txt

@@ -9,13 +9,18 @@ configure_file(
 
 add_library(muz-lib OBJECT
   # Audio
+  # =====
   Signal.cpp
   AudioEngine.cpp
   AudioConf.cpp
+  # signals
+  # -------
   Constant.cpp
   Sine.cpp
+  Noise.cpp
 
   # Language
+  # ========
   Node.cpp
   Lexer.cpp
   Parser.cpp

lib/Compiler.cpp

@@ -1,6 +1,10 @@
 #include "Compiler.hpp"
+
+// signals
+// -------
 #include "Constant.hpp"
 #include "Sine.hpp"
+#include "Noise.hpp"
 
 namespace muz
 {
@@ -38,23 +42,8 @@ namespace muz
             compile_node(node->child(i));
           }
 
-        if (name == "sine")
+        execute_cmd(name, node);
-          {
-            check_cmd_arity(*node, 2);
 
-            auto one = pop();
-            auto signal = std::make_unique<Sine>(m_conf,
-                                                 std::move(pop()),
-                                                 std::move(one));
-            push(std::move(signal));
-          }
-        else
-          {
-            throw compile_error {
-              std::string()
-              + "cannot compile unknown command '" + name + "'."
-            };
-          }
       } break;
 
       case NODE_DIR: {
@@ -84,6 +73,34 @@ namespace muz
       }
   }
 
+  void Compiler::execute_cmd(std::string const& name,
+                             std::shared_ptr<Node> node)
+  {
+    if (name == "sine")
+      {
+        check_cmd_arity(*node, 2);
+
+        auto one = pop();
+        auto signal = std::make_unique<Sine>(m_conf,
+                                             pop(),
+                                             std::move(one));
+        push(std::move(signal));
+      }
+    else if (name == "noise")
+      {
+        check_cmd_arity(*node, 0);
+        auto signal = std::make_unique<Noise>(m_conf);
+        push(std::move(signal));
+      }
+    else
+      {
+        throw compile_error {
+          std::string()
+          + "cannot compile unknown command '" + name + "'."
+        };
+      }
+  }
+
   void Compiler::push(std::unique_ptr<Signal> signal)
   {
     m_signals.push_back(std::move(signal));

lib/Compiler.hpp

@@ -24,6 +24,7 @@ namespace muz
 
     std::vector<std::unique_ptr<Signal>> compile(std::shared_ptr<Node> node);
     void compile_node(std::shared_ptr<Node> node);
+    void execute_cmd(std::string const& name, std::shared_ptr<Node> node);
 
   private:
     AudioConf const& m_conf;

lib/Noise.cpp

@@ -0,0 +1,28 @@
+#include "Noise.hpp"
+
+namespace muz
+{
+  /*explicit*/ Noise::Noise(AudioConf const& conf)
+    : m_conf { conf }
+  {
+    m_rand.seed(std::chrono::steady_clock::now().time_since_epoch().count());
+  }
+
+  /*virtual*/ Noise::~Noise()
+  {
+  }
+
+  std::vector<float> Noise::next() /*override*/
+  {
+    std::vector<float> out;
+
+    float value = m_distribution(m_rand);
+
+    for (int i=0; i<m_conf.channels(); i++)
+      {
+        out.push_back(value);
+      }
+
+    return out;
+  }
+}

lib/Noise.hpp

@@ -0,0 +1,27 @@
+#ifndef muz_NOISE_HPP
+#define muz_NOISE_HPP
+
+#include <random>
+#include <chrono>
+
+#include "commons.hpp"
+#include "AudioConf.hpp"
+#include "Signal.hpp"
+
+namespace muz
+{
+  class Noise: public Signal
+  {
+  public:
+    explicit Noise(AudioConf const& conf);
+    virtual ~Noise();
+
+    std::vector<float> next() override;
+  private:
+    AudioConf m_conf;
+    std::mt19937 m_rand;
+    std::uniform_real_distribution<float> m_distribution {-0.5f, 0.5f};
+  };
+}
+
+#endif