ASIO backend

.clang-format

@@ -0,0 +1,31 @@
+---
+
+BasedOnStyle: LLVM
+
+ColumnLimit: 120          # Arbitrary, feel free to adjust locally. 0 to ignore.
+PenaltyExcessCharacter: 1 # Softest limit on line length.
+ReflowComments: false     # Best we don't do this without a consistent length limit.
+
+AlwaysBreakTemplateDeclarations: true
+
+AllowShortFunctionsOnASingleLine: Empty
+
+SpaceAfterTemplateKeyword: false
+
+ConstructorInitializerIndentWidth: 2
+ContinuationIndentWidth: 2
+IndentWidth: 2
+
+AllowShortCaseLabelsOnASingleLine: true
+
+DerivePointerAlignment: true
+
+IndentCaseLabels: true
+
+BinPackArguments: false
+BinPackParameters: false
+
+---
+Language: Cpp
+
+...

.gitignore

@@ -1,3 +1,4 @@
 .idea
 cmake-build*
 .DS_Store
+/win_build

CMakeLists.txt

@@ -7,12 +7,21 @@ cmake_minimum_required(VERSION 3.12)
 project(libstdaudio)
 
 set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
+
+if (MSVC)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4 /WX")
+else ()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
+endif ()
 
 if (APPLE)
     set(CMAKE_EXE_LINKER_FLAGS "-framework CoreAudio")
 endif ()
 
+if (MSVC)
+    set(CMAKE_EXE_LINKER_FLAGS "winmm.lib")
+endif ()
+
 include_directories(include)
 
 add_executable(white_noise examples/white_noise.cpp)
@@ -24,4 +33,10 @@ add_executable(level_meter examples/level_meter.cpp)
 add_executable(test
         test/test_main.cpp
         test/audio_buffer_test.cpp
-        test/audio_device_test.cpp)
+        test/audio_device_test.cpp)
+
+if (MSVC)
+add_executable(test_asio
+        test/test_main.cpp
+        test/asio_test.cpp)
+endif ()

examples/level_meter.cpp

@@ -30,9 +30,9 @@ int main() {
 
     auto& in = *io.input_buffer;
 
-    for (int frame = 0; frame < in.size_frames(); ++frame) {
-      for (int channel = 0; channel < in.size_channels(); ++channel) {
-        float abs_value = std::abs(in(frame, channel));
+    for (size_t frame = 0; frame < in.size_frames(); ++frame) {
+      for (size_t channel = 0; channel < in.size_channels(); ++channel) {
+        const float abs_value = std::abs(in(frame, channel));
 
         if (abs_value > max_abs_value)
           max_abs_value.store(abs_value);
@@ -45,4 +45,4 @@ int main() {
     std::this_thread::sleep_for(std::chrono::milliseconds(250));
     std::cout << gain_to_db(max_abs_value.exchange(0)) << " dB\n";
   }
-}
+}

examples/melody.cpp

@@ -3,9 +3,14 @@
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 
+#ifdef WIN32
+#define _USE_MATH_DEFINES
+#endif
+
 #include <cmath>
 #include <array>
 #include <thread>
+#include <atomic>
 #include <audio>
 
 // This example app plays a short melody using a simple square wave synthesiser.
@@ -21,7 +26,7 @@ constexpr float bpm = 260.0;
 
 float note_to_frequency_hz(int note) {
   constexpr float pitch_standard_hz = 440.0f;
-  return pitch_standard_hz * std::pow(2.0f, float(note - 69) / 12.0f);
+  return pitch_standard_hz * std::pow(2.0f, static_cast<float>(note - 69) / 12.0f);
 }
 
 std::atomic<bool> stop = false;
@@ -30,7 +35,7 @@ struct synthesiser {
   float get_next_sample() {
     assert (_sample_rate > 0);
 
-    _ms_counter += 1000. / _sample_rate;
+    _ms_counter += 1000.0f / _sample_rate;
     if (_ms_counter >= _note_duration_ms) {
       _ms_counter = 0;
       if (++_current_note_index < notes.size()) {
@@ -42,8 +47,8 @@ struct synthesiser {
       }
     }
 
-    auto next_sample = std::copysign(0.1f, std::sin(_phase));
-    _phase = std::fmod(_phase + _delta, 2.0f * float(M_PI));
+    const auto next_sample = std::copysign(0.1f, std::sin(_phase));
+    _phase = std::fmod(_phase + _delta, 2.0f * static_cast<float>(M_PI));
     return next_sample;
   }
 
@@ -54,7 +59,7 @@ struct synthesiser {
 
 private:
   void update() noexcept {
-    float frequency_hz = note_to_frequency_hz(notes.at(_current_note_index));
+    const float frequency_hz = note_to_frequency_hz(notes.at(_current_note_index));
     _delta = 2.0f * frequency_hz * static_cast<float>(M_PI / _sample_rate);
   }
 
@@ -63,7 +68,7 @@ struct synthesiser {
   float _phase = 0;
   float _ms_counter = 0;
   float _note_duration_ms = 60'000.0f / bpm;
-  int _current_note_index = 0;
+  size_t _current_note_index = 0;
 };
 
 
@@ -75,18 +80,18 @@ int main() {
     return 1;
 
   auto synth = synthesiser();
-  synth.set_sample_rate(float(device->get_sample_rate()));
+  synth.set_sample_rate(static_cast<float>(device->get_sample_rate()));
 
   device->connect([=](audio_device&, audio_device_io<float>& io) mutable noexcept {
     if (!io.output_buffer.has_value())
       return;
 
     auto& out = *io.output_buffer;
 
-    for (int frame = 0; frame < out.size_frames(); ++frame) {
+    for (size_t frame = 0; frame < out.size_frames(); ++frame) {
       auto next_sample = synth.get_next_sample();
 
-      for (int channel = 0; channel < out.size_channels(); ++channel)
+      for (size_t channel = 0; channel < out.size_channels(); ++channel)
         out(frame, channel) = next_sample;
     }
   });
@@ -95,4 +100,4 @@ int main() {
   while (!stop.load()) {
     std::this_thread::sleep_for(std::chrono::milliseconds(50));
   }
-}
+}

examples/print_devices.cpp

@@ -28,7 +28,7 @@ void print_device_info(const audio_device& d) {
   std::cout << "buffer size = " << d.get_buffer_size_frames() << " frames, ";
   std::cout << (d.is_input() ? d.get_num_input_channels() : d.get_num_output_channels()) << " channels";
   std::cout << (is_default_device(d) ? " [DEFAULT DEVICE]\n" : "\n");
-};
+}
 
 void print_device_list(const audio_device_list& list) {
   for (auto& item : list) {

examples/sine_wave.cpp

@@ -3,6 +3,10 @@
 // Distributed under the Boost Software License, Version 1.0.
 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 
+#ifdef WIN32
+#define _USE_MATH_DEFINES
+#endif
+
 #include <cmath>
 #include <thread>
 #include <audio>
@@ -16,25 +20,25 @@ int main() {
   if (!device)
     return 1;
 
-  float frequency_hz = 440.0f;
-  float delta = 2.0f * frequency_hz * float(M_PI / device->get_sample_rate());
+  constexpr float frequency_hz = 440.0f;
+  const float delta = 2.0f * frequency_hz * static_cast<float>(M_PI / device->get_sample_rate());
   float phase = 0;
 
-  device->connect([=](audio_device& device, audio_device_io<float>& io) mutable noexcept {
+  device->connect([=](audio_device&, audio_device_io<float>& io) mutable noexcept {
     if (!io.output_buffer.has_value())
       return;
 
     auto& out = *io.output_buffer;
 
-    for (int frame = 0; frame < out.size_frames(); ++frame) {
-      float next_sample = std::sin(phase);
-      phase = std::fmod(phase + delta, 2.0f * M_PI);
+    for (size_t frame = 0; frame < out.size_frames(); ++frame) {
+      const float next_sample = std::sin(phase);
+      phase = std::fmod(phase + delta, 2.0f * static_cast<float>(M_PI));
 
-      for (int channel = 0; channel < out.size_channels(); ++channel)
+      for (size_t channel = 0; channel < out.size_channels(); ++channel)
         out(frame, channel) = 0.2f * next_sample;
     }
   });
 
   device->start();
   std::this_thread::sleep_for(std::chrono::seconds(5));
-}
+}

examples/white_noise.cpp

@@ -23,8 +23,8 @@ int main() {
 
       auto &out = *io.output_buffer;
 
-      for (int frame = 0; frame < out.size_frames(); ++frame)
-        for (int channel = 0; channel < out.size_channels(); ++channel)
+      for (size_t frame = 0; frame < out.size_frames(); ++frame)
+        for (size_t channel = 0; channel < out.size_channels(); ++channel)
           out(frame, channel) = white_noise(gen);
     });
 

include/__audio_buffer.h

@@ -5,6 +5,8 @@
 
 #pragma once
 
+#include <cassert>
+
 #include <chrono>
 
 _LIBSTDAUDIO_NAMESPACE_BEGIN
@@ -30,7 +32,7 @@ class audio_buffer {
       _stride(_num_channels),
       _is_contiguous(true) {
     assert (num_channels <= _max_num_channels);
-    for (auto i = 0; i < _num_channels; ++i) {
+    for (index_type i = 0; i < _num_channels; ++i) {
       _channels[i] = data + i;
     }
   }
@@ -41,12 +43,12 @@ class audio_buffer {
         _stride(1),
         _is_contiguous(true) {
     assert (num_channels <= _max_num_channels);
-    for (auto i = 0; i < _num_channels; ++i) {
+    for (index_type i = 0; i < _num_channels; ++i) {
       _channels[i] = data + (i * _num_frames);
     }
   }
 
-  audio_buffer(sample_type** data, index_type num_frames, index_type num_channels,ptr_to_ptr_deinterleaved_t)
+  audio_buffer(sample_type** data, index_type num_frames, index_type num_channels, ptr_to_ptr_deinterleaved_t)
       : _num_frames(num_frames),
         _num_channels(num_channels),
         _stride(1),

include/audio

@@ -7,10 +7,6 @@
 
 #include <optional>
 
-// TODO: this is a temporary measure until std::span becomes available
-#include "cpp/span.hpp"
-using namespace TCB_SPAN_NAMESPACE_NAME;
-
 #define _LIBSTDAUDIO_NAMESPACE std::experimental
 
 #define _LIBSTDAUDIO_NAMESPACE_BEGIN namespace _LIBSTDAUDIO_NAMESPACE {
@@ -21,6 +17,8 @@ using namespace TCB_SPAN_NAMESPACE_NAME;
 
 #ifdef __APPLE__
   #include <audio_backend/__coreaudio_backend.h>
+#elif defined _WIN32
+  #include <audio_backend/__asio_backend.h>
 #else
   #include <audio_backend/__null_backend.h>
 #endif // __APPLE__