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Split software audio mixer to its own file

This will be shared between the SDL2 and miniaudio backends,
eliminating all that digusting duplicate code.

--- a/CMakeLists.txt

+++ b/CMakeLists.txt

@@ -296,7 +296,7 @@

 if(BACKEND_AUDIO MATCHES "SDL2")

 	target_sources(CSE2 PRIVATE "src/Backends/Audio/SDL2.cpp")

 elseif(BACKEND_AUDIO MATCHES "miniaudio")

-	target_sources(CSE2 PRIVATE "src/Backends/Audio/miniaudio.cpp")

+	target_sources(CSE2 PRIVATE "src/Backends/Audio/miniaudio.cpp" "src/Backends/Audio/SoftwareMixer.cpp")

 	# Link libdl, libm, and libpthread

 	include(CheckLibraryExists)

--- /dev/null

+++ b/src/Backends/Audio/SoftwareMixer.cpp

@@ -1,0 +1,185 @@

+#include "SoftwareMixer.h"

+

+#include <math.h>

+#include <stddef.h>

+#include <stdio.h>

+#include <stdlib.h>

+#include <string.h>

+

+#define MIN(a, b) ((a) < (b) ? (a) : (b))

+#define MAX(a, b) ((a) > (b) ? (a) : (b))

+#define CLAMP(x, y, z) MIN(MAX((x), (y)), (z))

+

+#ifdef __GNUC__

+#define ATTR_HOT __attribute__((hot))

+#else

+#define ATTR_HOT

+#endif

+

+struct Mixer_Sound

+{

+	unsigned char *samples;

+	size_t frames;

+	double position;

+	double advance_delta;

+	bool playing;

+	bool looping;

+	unsigned int frequency;

+	float volume;

+	float pan_l;

+	float pan_r;

+	float volume_l;

+	float volume_r;

+

+	struct Mixer_Sound *next;

+};

+

+static Mixer_Sound *sound_list_head;

+

+static unsigned long output_frequency;

+

+static double MillibelToScale(long volume)

+{

+	// Volume is in hundredths of a decibel, from 0 to -10000

+	volume = CLAMP(volume, -10000, 0);

+	return pow(10.0, volume / 2000.0);

+}

+

+void Mixer_Init(unsigned long frequency)

+{

+	output_frequency = frequency;

+}

+

+Mixer_Sound* Mixer_CreateSound(unsigned int frequency, size_t frames)

+{

+	Mixer_Sound *sound = (Mixer_Sound*)malloc(sizeof(Mixer_Sound));

+

+	if (sound == NULL)

+		return NULL;

+

+	sound->samples = (unsigned char*)malloc(frames + 1);

+

+	if (sound->samples == NULL)

+	{

+		free(sound);

+		return NULL;

+	}

+

+	sound->frames = frames;

+	sound->playing = false;

+	sound->position = 0.0;

+

+	Mixer_SetSoundFrequency(sound, frequency);

+	Mixer_SetSoundVolume(sound, 0);

+	Mixer_SetSoundPan(sound, 0);

+

+	sound->next = sound_list_head;

+	sound_list_head = sound;

+

+	return sound;

+}

+

+void Mixer_DestroySound(Mixer_Sound *sound)

+{

+	for (Mixer_Sound **sound_pointer = &sound_list_head; *sound_pointer != NULL; sound_pointer = &(*sound_pointer)->next)

+	{

+		if (*sound_pointer == sound)

+		{

+			*sound_pointer = sound->next;

+			free(sound->samples);

+			free(sound);

+			break;

+		}

+	}

+}

+

+unsigned char* Mixer_LockSound(Mixer_Sound *sound, size_t *size)

+{

+	if (size != NULL)

+		*size = sound->frames;

+

+	return sound->samples;

+}

+

+void Mixer_PlaySound(Mixer_Sound *sound, bool looping)

+{

+	sound->playing = true;

+	sound->looping = looping;

+

+	sound->samples[sound->frames] = looping ? sound->samples[0] : 0x80;	// For the linear interpolator

+}

+

+void Mixer_StopSound(Mixer_Sound *sound)

+{

+	sound->playing = false;

+	sound->position = 0.0;

+}

+

+void Mixer_RewindSound(Mixer_Sound *sound)

+{

+	sound->position = 0.0;

+}

+

+void Mixer_SetSoundFrequency(Mixer_Sound *sound, unsigned int frequency)

+{

+	sound->frequency = frequency;

+	sound->advance_delta = (double)frequency / (double)output_frequency;

+}

+

+void Mixer_SetSoundVolume(Mixer_Sound *sound, long volume)

+{

+	sound->volume = (float)MillibelToScale(volume);

+

+	sound->volume_l = sound->pan_l * sound->volume;

+	sound->volume_r = sound->pan_r * sound->volume;

+}

+

+void Mixer_SetSoundPan(Mixer_Sound *sound, long pan)

+{

+	sound->pan_l = (float)MillibelToScale(-pan);

+	sound->pan_r = (float)MillibelToScale(pan);

+

+	sound->volume_l = sound->pan_l * sound->volume;

+	sound->volume_r = sound->pan_r * sound->volume;

+}

+

+// Most CPU-intensive function in the game (2/3rd CPU time consumption in my experience), so marked with attrHot so the compiler considers it a hot spot (as it is) when optimizing

+ATTR_HOT void Mixer_MixSounds(float *stream, unsigned int frames_total)

+{

+	for (Mixer_Sound *sound = sound_list_head; sound != NULL; sound = sound->next)

+	{

+		if (sound->playing)

+		{

+			float *steam_pointer = stream;

+

+			for (unsigned int frames_done = 0; frames_done < frames_total; ++frames_done)

+			{

+				// Get two samples, and normalise them to 0-1

+				const float sample1 = (sound->samples[(size_t)sound->position] - 128.0f) / 128.0f;

+				const float sample2 = (sound->samples[(size_t)sound->position + 1] - 128.0f) / 128.0f;

+

+				// Perform linear interpolation

+				const float interpolated_sample = sample1 + ((sample2 - sample1) * fmod((float)sound->position, 1.0f));

+

+				*steam_pointer++ += interpolated_sample * sound->volume_l;

+				*steam_pointer++ += interpolated_sample * sound->volume_r;

+

+				sound->position += sound->advance_delta;

+

+				if (sound->position >= sound->frames)

+				{

+					if (sound->looping)

+					{

+						sound->position = fmod(sound->position, (double)sound->frames);

+					}

+					else

+					{

+						sound->playing = false;

+						sound->position = 0.0;

+						break;

+					}

+				}

+			}

+		}

+	}

+}

--- /dev/null

+++ b/src/Backends/Audio/SoftwareMixer.h

@@ -1,0 +1,17 @@

+#pragma once

+

+#include <stddef.h>

+

+typedef struct Mixer_Sound Mixer_Sound;

+

+void Mixer_Init(unsigned long frequency);

+Mixer_Sound* Mixer_CreateSound(unsigned int frequency, size_t frames);

+void Mixer_DestroySound(Mixer_Sound *sound);

+unsigned char* Mixer_LockSound(Mixer_Sound *sound, size_t *size);

+void Mixer_PlaySound(Mixer_Sound *sound, bool looping);

+void Mixer_StopSound(Mixer_Sound *sound);

+void Mixer_RewindSound(Mixer_Sound *sound);

+void Mixer_SetSoundFrequency(Mixer_Sound *sound, unsigned int frequency);

+void Mixer_SetSoundVolume(Mixer_Sound *sound, long volume);

+void Mixer_SetSoundPan(Mixer_Sound *sound, long pan);

+void Mixer_MixSounds(float *stream, unsigned int frames_total);

--- a/src/Backends/Audio/miniaudio.cpp

+++ b/src/Backends/Audio/miniaudio.cpp

@@ -1,11 +1,5 @@

 #include "../Audio.h"

-#include <math.h>

-#include <stddef.h>

-#include <stdio.h>

-#include <stdlib.h>

-#include <string.h>

-

 #define MINIAUDIO_IMPLEMENTATION

 #define MA_NO_DECODING

 #define MA_API static

@@ -14,35 +8,10 @@

 #include "../../Organya.h"

 #include "../../WindowsWrapper.h"

+#include "SoftwareMixer.h"

+

 #define MIN(a, b) ((a) < (b) ? (a) : (b))

-#define MAX(a, b) ((a) > (b) ? (a) : (b))

-#define CLAMP(x, y, z) MIN(MAX((x), (y)), (z))

-#ifdef __GNUC__

-#define ATTR_HOT __attribute__((hot))

-#else

-#define ATTR_HOT

-#endif

-

-struct AudioBackend_Sound

-{

-	unsigned char *samples;

-	size_t frames;

-	double position;

-	double advance_delta;

-	BOOL playing;

-	BOOL looping;

-	unsigned int frequency;

-	float volume;

-	float pan_l;

-	float pan_r;

-	float volume_l;

-	float volume_r;

-

-	struct AudioBackend_Sound *next;

-};

-

-static AudioBackend_Sound *sound_list_head;

 static ma_device device;

 static ma_mutex mutex;

 static ma_mutex organya_mutex;

@@ -51,81 +20,6 @@

 static unsigned short organya_timer;

-static double MillibelToScale(long volume)

-{

-	// Volume is in hundredths of decibels, from 0 to -10000

-	volume = CLAMP(volume, -10000, 0);

-	return pow(10.0, volume / 2000.0);

-}

-

-static void SetSoundFrequency(AudioBackend_Sound *sound, unsigned int frequency)

-{

-	sound->frequency = frequency;

-	sound->advance_delta = (double)frequency / (double)output_frequency;

-}

-

-static void SetSoundVolume(AudioBackend_Sound *sound, long volume)

-{

-	sound->volume = (float)MillibelToScale(volume);

-

-	sound->volume_l = sound->pan_l * sound->volume;

-	sound->volume_r = sound->pan_r * sound->volume;

-}

-

-static void SetSoundPan(AudioBackend_Sound *sound, long pan)

-{

-	sound->pan_l = (float)MillibelToScale(-pan);

-	sound->pan_r = (float)MillibelToScale(pan);

-

-	sound->volume_l = sound->pan_l * sound->volume;

-	sound->volume_r = sound->pan_r * sound->volume;

-}

-

-// Most CPU-intensive function in the game (2/3rd CPU time consumption in my experience), so marked with attrHot so the compiler considers it a hot spot (as it is) when optimizing

-ATTR_HOT static void MixSounds(float *stream, unsigned int frames_total)

-{

-	ma_mutex_lock(&mutex);

-

-	for (AudioBackend_Sound *sound = sound_list_head; sound != NULL; sound = sound->next)

-	{

-		if (sound->playing)

-		{

-			float *steam_pointer = stream;

-

-			for (unsigned int frames_done = 0; frames_done < frames_total; ++frames_done)

-			{

-				// Get two samples, and normalise them to 0-1

-				const float sample1 = (sound->samples[(size_t)sound->position] - 128.0f) / 128.0f;

-				const float sample2 = (sound->samples[(size_t)sound->position + 1] - 128.0f) / 128.0f;

-

-				// Perform linear interpolation

-				const float interpolated_sample = sample1 + ((sample2 - sample1) * fmod((float)sound->position, 1.0f));

-

-				*steam_pointer++ += interpolated_sample * sound->volume_l;

-				*steam_pointer++ += interpolated_sample * sound->volume_r;

-

-				sound->position += sound->advance_delta;

-

-				if (sound->position >= sound->frames)

-				{

-					if (sound->looping)

-					{

-						sound->position = fmod(sound->position, (double)sound->frames);

-					}

-					else

-					{

-						sound->playing = FALSE;

-						sound->position = 0.0;

-						break;

-					}

-				}

-			}

-		}

-	}

-

-	ma_mutex_unlock(&mutex);

-}

-

 static void Callback(ma_device *device, void *output_stream, const void *input_stream, ma_uint32 frames_total)

 {

 	(void)device;

@@ -137,7 +31,9 @@

 	if (organya_timer == 0)

 	{

-		MixSounds(stream, frames_total);

+		ma_mutex_lock(&mutex);

+		Mixer_MixSounds(stream, frames_total);

+		ma_mutex_unlock(&mutex);

 	}

 	else

 	{

@@ -160,7 +56,9 @@

 			const unsigned int frames_to_do = MIN(organya_countdown, frames_total - frames_done);

-			MixSounds(stream + frames_done * 2, frames_to_do);

+			ma_mutex_lock(&mutex);

+			Mixer_MixSounds(stream + frames_done * 2, frames_to_do);

+			ma_mutex_unlock(&mutex);

 			frames_done += frames_to_do;

 			organya_countdown -= frames_to_do;

@@ -182,14 +80,18 @@

 	if (ma_device_init(NULL, &config, &device) == MA_SUCCESS)

 	{

-		output_frequency = device.sampleRate;

-

 		if (ma_mutex_init(device.pContext, &mutex) == MA_SUCCESS)

 		{

 			if (ma_mutex_init(device.pContext, &organya_mutex) == MA_SUCCESS)

 			{

 				if (ma_device_start(&device) == MA_SUCCESS)

+				{

+					output_frequency = device.sampleRate;

+

+					Mixer_Init(device.sampleRate);

+

 					return TRUE;

+				}

 				ma_mutex_uninit(&organya_mutex);

 			}

@@ -216,35 +118,13 @@

 AudioBackend_Sound* AudioBackend_CreateSound(unsigned int frequency, size_t frames)

 {

-	AudioBackend_Sound *sound = (AudioBackend_Sound*)malloc(sizeof(AudioBackend_Sound));

-

-	if (sound == NULL)

-		return NULL;

-

-	sound->samples = (unsigned char*)malloc(frames + 1);

-

-	if (sound->samples == NULL)

-	{

-		free(sound);

-		return NULL;

-	}

-

-	sound->frames = frames;

-	sound->playing = FALSE;

-	sound->position = 0.0;

-

-	SetSoundFrequency(sound, frequency);

-	SetSoundVolume(sound, 0);

-	SetSoundPan(sound, 0);

-

 	ma_mutex_lock(&mutex);

-	sound->next = sound_list_head;

-	sound_list_head = sound;

+	Mixer_Sound *sound = Mixer_CreateSound(frequency, frames);

 	ma_mutex_unlock(&mutex);

-	return sound;

+	return (AudioBackend_Sound*)sound;

 }

 void AudioBackend_DestroySound(AudioBackend_Sound *sound)

@@ -254,16 +134,7 @@

 	ma_mutex_lock(&mutex);

-	for (AudioBackend_Sound **sound_pointer = &sound_list_head; *sound_pointer != NULL; sound_pointer = &(*sound_pointer)->next)

-	{

-		if (*sound_pointer == sound)

-		{

-			*sound_pointer = sound->next;

-			free(sound->samples);

-			free(sound);

-			break;

-		}

-	}

+	Mixer_DestroySound((Mixer_Sound*)sound);

 	ma_mutex_unlock(&mutex);

 }

@@ -275,10 +146,7 @@

 	ma_mutex_lock(&mutex);

-	if (size != NULL)

-		*size = sound->frames;

-

-	return sound->samples;

+	return Mixer_LockSound((Mixer_Sound*)sound, size);

 }

 void AudioBackend_UnlockSound(AudioBackend_Sound *sound)

@@ -296,11 +164,8 @@

 	ma_mutex_lock(&mutex);

-	sound->playing = TRUE;

-	sound->looping = looping;

+	Mixer_PlaySound((Mixer_Sound*)sound, looping);

-	sound->samples[sound->frames] = looping ? sound->samples[0] : 0x80;	// For the linear interpolator

-

 	ma_mutex_unlock(&mutex);

 }

@@ -311,8 +176,7 @@

 	ma_mutex_lock(&mutex);

-	sound->playing = FALSE;

-	sound->position = 0.0;

+	Mixer_StopSound((Mixer_Sound*)sound);

 	ma_mutex_unlock(&mutex);

 }

@@ -324,7 +188,7 @@

 	ma_mutex_lock(&mutex);

-	sound->position = 0.0;

+	Mixer_RewindSound((Mixer_Sound*)sound);

 	ma_mutex_unlock(&mutex);

 }

@@ -336,7 +200,7 @@

 	ma_mutex_lock(&mutex);

-	SetSoundFrequency(sound, frequency);

+	Mixer_SetSoundFrequency((Mixer_Sound*)sound, frequency);

 	ma_mutex_unlock(&mutex);

 }

@@ -348,7 +212,7 @@

 	ma_mutex_lock(&mutex);

-	SetSoundVolume(sound, volume);

+	Mixer_SetSoundVolume((Mixer_Sound*)sound, volume);

 	ma_mutex_unlock(&mutex);

 }

@@ -360,7 +224,7 @@

 	ma_mutex_lock(&mutex);

-	SetSoundPan(sound, pan);

+	Mixer_SetSoundPan((Mixer_Sound*)sound, pan);

 	ma_mutex_unlock(&mutex);

 }

-- 

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