Initial commit

src/window/audio.c

@@ -0,0 +1,112 @@
+#include "audio.h"
+
+#include <SDL2/SDL.h>
+
+#include "../errors.h"
+
+// the maximum amount of sounds that can play at once
+#define MAX_SOUNDS 64
+
+typedef struct {
+    AudioData* playing_audio;
+    AudioDevice audio_device;
+} AudioCallbackData;
+
+// audio callback from SDL_AudioSpec; called when the audio device needs more data
+static void audio_mixer(void* userdata, Uint8* stream, int len) {
+    memset(stream, 0, len);         // clear the playing audio
+    AudioDevice* device = userdata; // get the callback data
+    AudioData* audio = device->playing_audio;
+
+    for (int i = 0; i < MAX_SOUNDS; i++) {
+        // skip if the audio doesn't conain any further data
+        if (audio[i].length <= 0) {
+            continue;
+        }
+
+        // get the length of which we shall be mixing
+        Uint32 mix_length = SDL_min(audio[i].length, len);
+
+        // mix the audio with the stream
+        SDL_MixAudioFormat(stream, audio[i].buffer, device->format, mix_length, SDL_MIX_MAXVOLUME);
+        audio[i].buffer += mix_length; // move the pointer up a a bit
+        audio[i].length -= mix_length; // move up the mixed amount
+    }
+}
+
+// converts the audio to the format of the audio device
+static void convert_audio(const AudioDevice* audio_device, const SDL_AudioSpec wav_spec, Uint8** wav_buffer, Uint32* wav_length) {
+    // build the audio converter with the audio given
+    SDL_AudioCVT cvt = {0};
+    SDL_BuildAudioCVT(&cvt, wav_spec.format, wav_spec.channels, wav_spec.freq, audio_device->format, audio_device->channels, audio_device->freq);
+
+    cvt.len = (*wav_length) * wav_spec.channels;          // the buffer length
+    cvt.buf = (Uint8*)SDL_malloc(cvt.len * cvt.len_mult); // allocate size for the new buffer
+    memcpy(cvt.buf, *wav_buffer, *wav_length);            // copy wav data to cvt buffer;
+
+    // convert
+    SDL_ConvertAudio(&cvt);
+
+    // output
+    *wav_length = cvt.len_cvt;                 // set the length to the new length
+    memcpy(*wav_buffer, cvt.buf, cvt.len_cvt); // copy converted cvt buffer back to wav buffer
+
+    free(cvt.buf); // free the memory allocated to the cvt buffer
+}
+
+// loads a WAV file and returns the relevant information
+AudioData audio_load_wav(const AudioDevice* audio_device, const char* file_path) {
+    SDL_AudioSpec wav_spec = {0};
+    AudioData audio = {0};
+
+    SDL_LoadWAV(file_path, &wav_spec, &audio.buffer, &audio.length);
+    convert_audio(audio_device, wav_spec, &audio.buffer, &audio.length);
+    audio.mixed_amount = audio.length;
+
+    return audio;
+}
+
+// initializes the audio device
+AudioDevice* audio_device_init(const int freq, const SDL_AudioFormat format, const Uint8 channels, const Uint16 samples) {
+    // allocate memory for the audio device
+    AudioDevice* audio_device = malloc(sizeof(AudioDevice));
+
+    // define the audio specification
+    SDL_AudioSpec spec = {freq, format, channels, samples};
+    spec.callback = audio_mixer;
+    spec.userdata = audio_device;
+
+    // create the audio device
+    *audio_device = (AudioDevice){
+        SDL_OpenAudioDevice(NULL, 0, &spec, NULL, 0),
+        freq,
+        format,
+        channels,
+        calloc(MAX_SOUNDS, sizeof(AudioData)), // allocate memory on the heap for the playing audio array
+    };
+
+    // if the audio device isn't set, cause an error
+    if (audio_device->id < 1) {
+        error(ERROR_SDL_AUDIO_INIT, "AudioDivice failed to open! SDL Error: %s", SDL_GetError());
+        return NULL;
+    }
+
+    // default state of the device is paused, so we unpause it here
+    SDL_PauseAudioDevice(audio_device->id, 0);
+    return audio_device;
+}
+
+// plays the audio
+void audio_play(const AudioDevice* audio_device, const AudioData audio) {
+    AudioData* playing_audio = audio_device->playing_audio;
+
+    for (int i = 0; i < MAX_SOUNDS; i++) {
+        // overrite audio that has been deallocated
+        if (playing_audio[i].length <= 0) {
+
+            // override the audio
+            playing_audio[i] = audio;
+            break; // don't continue. :3
+        }
+    }
+}