add audio output. HARK HARK HARK

src/frontend/Util_Audio.cpp

@@ -0,0 +1,77 @@
+/*
+    Copyright 2016-2020 Arisotura
+
+    This file is part of melonDS.
+
+    melonDS is free software: you can redistribute it and/or modify it under
+    the terms of the GNU General Public License as published by the Free
+    Software Foundation, either version 3 of the License, or (at your option)
+    any later version.
+
+    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with melonDS. If not, see http://www.gnu.org/licenses/.
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+
+#include "FrontendUtil.h"
+#include "Config.h"
+#include "qt_sdl/PlatformConfig.h" // FIXME!!!
+#include "Platform.h"
+
+#include "NDS.h"
+#include "GBACart.h"
+
+
+namespace Frontend
+{
+
+int AudioOut_Freq;
+float AudioOut_SampleFrac;
+
+
+void Init_Audio(int outputfreq)
+{
+    AudioOut_Freq = outputfreq;
+    AudioOut_SampleFrac = 0;
+}
+
+int AudioOut_GetNumSamples(int outlen)
+{
+    float f_len_in = (outlen * 32823.6328125) / (float)AudioOut_Freq;
+    f_len_in += AudioOut_SampleFrac;
+    int len_in = (int)floor(f_len_in);
+    AudioOut_SampleFrac = f_len_in - len_in;
+
+    return len_in;
+}
+
+void AudioOut_Resample(s16* inbuf, int inlen, s16* outbuf, int outlen)
+{
+    float res_incr = inlen / (float)outlen;
+    float res_timer = 0;
+    int res_pos = 0;
+
+    int volume = Config::AudioVolume;
+
+    for (int i = 0; i < outlen; i++)
+    {
+        outbuf[i*2  ] = (inbuf[res_pos*2  ] * volume) >> 8;
+        outbuf[i*2+1] = (inbuf[res_pos*2+1] * volume) >> 8;
+
+        res_timer += res_incr;
+        while (res_timer >= 1.0)
+        {
+            res_timer -= 1.0;
+            res_pos++;
+        }
+    }
+}
+
+}