feat(sound): add beeper

CMakeLists.txt

@@ -19,6 +19,7 @@ add_subdirectory(base)
 
 add_subdirectory(processor)
 add_subdirectory(display)
+add_subdirectory(sound)
 
 target_link_libraries(cchip8 PRIVATE SDL2::SDL2 SDL2::SDL2main)
 # use custom entry point

processor/include/processor/processor.h

@@ -21,6 +21,14 @@ class machine
 		START_ADDRESS = 0x200,
 	};
 
+	enum audio_frequencies
+	{
+		TIMER_BEEP = 440,
+		ERROR_BEEP = 350,
+	};
+
+	static constexpr size_t BEEP_DURATION = 20;
+
 	enum general_purpose_registers
 	{
 		V0,

processor/processor.cpp

@@ -8,13 +8,15 @@
 #include <gsl/gsl>
 
 #include "processor/processor.h"
+#include "sound/beeper.h"
 
 using namespace std;
 using namespace std::chrono;
 
 using namespace gsl;
 
 using namespace cchip8::processor;
+using namespace cchip8::sound;
 
 machine::machine()
 		: reg_pc_(START_ADDRESS),
@@ -45,8 +47,11 @@ void machine::cycle()
 
 	if (sound_timer_ > 0)
 	{
-		// TODO: go off a beep
 		sound_timer_ -= 1;
+
+		beeper b{};
+		b.beep(TIMER_BEEP, BEEP_DURATION);
+		b.wait();
 	}
 }
 
@@ -105,8 +110,8 @@ void machine::load(std::string_view filename)
 
 void machine::op_default()
 {
-	// TODO: logging and/or sounding
-	int fuck = 0;
+	beeper b{};
+	b.beep(ERROR_BEEP, BEEP_DURATION);
 }
 
 // 00e0: clear the screen

sound/CMakeLists.txt

@@ -1,3 +1,6 @@
 cmake_minimum_required(VERSION 3.21)
 
+target_sources(cchip8
+        PRIVATE beeper.cpp)
+
 target_include_directories(cchip8 PRIVATE include)

sound/beeper.cpp

@@ -0,0 +1,100 @@
+//
+// Created by cleve on 1/16/2022.
+//
+
+#include "sound/beeper.h"
+
+#include <cmath>
+#include <stdexcept>
+
+using namespace std;
+
+cchip8::sound::beeper::beeper()
+{
+	SDL_AudioSpec spec;
+
+	spec.freq = FREQUENCY;
+	spec.format = AUDIO_S16SYS;
+	spec.channels = 1;
+	spec.samples = 2048;
+	spec.callback = callback;
+	spec.userdata = this;
+
+	SDL_AudioSpec obtained;
+
+	// you might want to look for errors here
+	if (SDL_OpenAudio(&spec, &obtained) != 0)
+	{
+		throw runtime_error{ SDL_GetError() };
+	}
+
+	// start play audio
+	SDL_PauseAudio(0);
+}
+
+cchip8::sound::beeper::~beeper()
+{
+	SDL_CloseAudio();
+}
+
+void cchip8::sound::beeper::beep(double freq, int duration)
+{
+	SDL_LockAudio();
+	beep_segs_.emplace(freq, duration * FREQUENCY / 1000);
+	SDL_UnlockAudio();
+}
+
+void cchip8::sound::beeper::wait()
+{
+	int size = 0;
+	do
+	{
+		SDL_Delay(20);
+		SDL_LockAudio();
+		size = beep_segs_.size();
+		SDL_UnlockAudio();
+	} while (size > 0);
+}
+
+void cchip8::sound::beeper::sample(std::span<Sint16> stream)
+{
+	int i = 0;
+	while (i < stream.size())
+	{
+
+		if (beep_segs_.empty())
+		{
+			while (i < stream.size())
+			{
+				stream[i] = 0;
+				i++;
+			}
+			return;
+		}
+		auto& bo = beep_segs_.front();
+
+		int samples_count = std::min(i + bo.second, (int)stream.size());
+		bo.second -= samples_count - i;
+
+		while (i < samples_count)
+		{
+			stream[i] = AMPLITUDE * std::sin(v_ * 2 * 3.1415926f / FREQUENCY);
+			i++;
+			v_ += bo.first;
+		}
+
+		if (bo.second == 0)
+		{
+			beep_segs_.pop();
+		}
+	}
+}
+
+void cchip8::sound::beeper::callback(void* b, Uint8* s, int len)
+{
+	auto* stream = (Sint16*)s;
+	int length = len / 2;
+	auto* bp = (beeper*)b;
+
+	bp->sample({ stream, (size_t)length });
+}

sound/include/sound/beeper.h

@@ -0,0 +1,43 @@
+//
+// Created by cleve on 1/16/2022.
+//
+
+#pragma once
+
+#include <queue>
+#include <utility>
+#include <span>
+
+#include <SDL.h>
+#include <SDL_audio.h>
+
+namespace cchip8::sound
+{
+class beeper
+{
+public:
+	static constexpr int AMPLITUDE = 28000;
+	static constexpr int FREQUENCY = 44100;
+
+	beeper();
+
+	~beeper();
+
+	beeper(beeper&&) = delete;
+
+	beeper(const beeper&) = delete;
+
+	beeper& operator=(const beeper&) = delete;
+
+	void beep(double freq,int duration);
+
+	void wait();
+
+private:
+	void sample(std::span<Sint16> stream);
+	static void callback(void*,Uint8*,int);
+
+	double v_{};
+	std::queue<std::pair<double, int>> beep_segs_{};
+};
+}