From d5262780f4922194bd38dbc57cf0397c2f3ff9dc Mon Sep 17 00:00:00 2001
From: Raimon Zamora <jaildoctor@gmail.com>
Date: Wed, 15 Sep 2021 11:58:22 +0200
Subject: [PATCH] now using AudioCallback

---
 main.cpp | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/main.cpp b/main.cpp
index 33a163e..199c71e 100755
--- a/main.cpp
+++ b/main.cpp
@@ -25,7 +25,20 @@ int current_instrument = 0;
 int current_volume = 2;
 int current_effect = 0;
 
-SDL_AudioSpec audioSpec{SAMPLES_PER_SECOND, AUDIO_FORMAT, 1, 0, 512, 0, 0, NULL, NULL};
+toneGen tonegen(SOUND_NUM_SAMPLES);
+SDL_AudioDeviceID sdlAudioDevice;
+
+void audioCallback(void* userdata, Uint8* stream, int len) {
+    Sint16* buffer = (Sint16*)stream;
+    int numSamples = tonegen.getSamples(len >> 1, buffer);
+    if (numSamples*2 < len) {
+        int rest = len - numSamples*2;
+        SDL_memset(&stream[numSamples*2], 0, rest);
+        SDL_PauseAudioDevice(sdlAudioDevice, 1);
+    }
+}
+
+SDL_AudioSpec audioSpec{SAMPLES_PER_SECOND, AUDIO_FORMAT, 1, 0, 512, 0, 0, &audioCallback, NULL};
 
 const char get_hex(const uint8_t num) {
     static const char hexstr[17] = "0123456789ABCDEF";
@@ -35,15 +48,14 @@ const char get_hex(const uint8_t num) {
 int main(int argc, char* argv[]) {
     pattern[0][0] = (34<<10) + (2<<8) + (7<<4) + 5;
     SDL_Init(SDL_INIT_EVERYTHING);
-    SDL_AudioDeviceID sdlAudioDevice = SDL_OpenAudioDevice(NULL, 0, &audioSpec, NULL, 0);
+    sdlAudioDevice = SDL_OpenAudioDevice(NULL, 0, &audioSpec, NULL, 0);
 
     AUDIO_FORMAT_TYPE beeps[int(SOUND_NUM_SAMPLES*8)];
     AUDIO_FORMAT_TYPE beeps2[int(SOUND_NUM_SAMPLES*8)];
     AUDIO_FORMAT_TYPE *pointer = beeps;
 
-    toneGen tonegen(SOUND_NUM_SAMPLES);
 
-    tonegen.setup(22, CHIPTUNE_INSTRUMENT_TRIANGLE, 13, CHIPTUNE_EFFECT_DROP);
+    /*tonegen.setup(22, CHIPTUNE_INSTRUMENT_TRIANGLE, 13, CHIPTUNE_EFFECT_DROP);
     int numSamples = tonegen.getSamples(SOUND_NUM_SAMPLES, pointer); pointer += int(SOUND_NUM_SAMPLES);
     tonegen.setup(32, CHIPTUNE_INSTRUMENT_SQUARE, 0, CHIPTUNE_EFFECT_NONE);
     numSamples = tonegen.getSamples(SOUND_NUM_SAMPLES, pointer); pointer += int(SOUND_NUM_SAMPLES);
@@ -77,6 +89,7 @@ int main(int argc, char* argv[]) {
     numSamples = tonegen.getSamples(SOUND_NUM_SAMPLES, pointer); pointer += int(SOUND_NUM_SAMPLES);
     tonegen.setup(47, CHIPTUNE_INSTRUMENT_SQUARE, 1, CHIPTUNE_EFFECT_NONE);
     numSamples = tonegen.getSamples(SOUND_NUM_SAMPLES, pointer); pointer += int(SOUND_NUM_SAMPLES);
+    */
 
     for (int i=0; i<SOUND_NUM_SAMPLES*8;++i) {
         beeps[i] += beeps2[i];
@@ -145,8 +158,6 @@ int main(int argc, char* argv[]) {
                 if ((key == SDL_SCANCODE_PERIOD) || (key == SDL_SCANCODE_DELETE)) note.Set(0);
                 if (key == SDL_SCANCODE_SPACE) {
                     tonegen.setup(note.Get());
-                    numSamples = tonegen.getSamples(SOUND_NUM_SAMPLES, beeps);
-                    SDL_QueueAudio(sdlAudioDevice, &beeps[0], SOUND_SIZE_IN_BYTES);
                     SDL_PauseAudioDevice(sdlAudioDevice, 0);
                 }
                 if (selected_part==0) {
@@ -168,8 +179,6 @@ int main(int argc, char* argv[]) {
                     };
                     if (m) {
                         tonegen.setup(note.Get());
-                        numSamples = tonegen.getSamples(SOUND_NUM_SAMPLES, beeps);
-                        SDL_QueueAudio(sdlAudioDevice, &beeps[0], SOUND_SIZE_IN_BYTES);
                         SDL_PauseAudioDevice(sdlAudioDevice, 0);
                     }
                 }