API CHANGE: Change the data callback in preparation for full-duplex.

This removes the two separate callbacks for sending and receiving data
to/from the device to a unified callback that's used for both input and
output. The new callback takes a pointer to both an input and output
buffer. When the device is opened in playback mode the input pointer
will be set to null. Likewise the output pointer will be set to null
for capture devices. Both input and output pointers will be non-null
for full-duplex devices.

examples/simple_capture.c

@@ -12,7 +12,7 @@ mal_uint32 capturedSampleCount = 0;
 mal_int16* pCapturedSamples = NULL;
 mal_uint32 playbackSample = 0;
 
-void on_recv_frames(mal_device* pDevice, mal_uint32 frameCount, const void* pSamples)
+void on_recv_frames(mal_device* pDevice, const void* pInput, void* pOutput, mal_uint32 frameCount)
 {
     mal_uint32 sampleCount = frameCount * pDevice->channels;
 
@@ -22,13 +22,15 @@ void on_recv_frames(mal_device* pDevice, mal_uint32 frameCount, const void* pSam
         return;
     }
 
-    memcpy(pNewCapturedSamples + capturedSampleCount, pSamples, sampleCount * sizeof(mal_int16));
+    memcpy(pNewCapturedSamples + capturedSampleCount, pInput, sampleCount * sizeof(mal_int16));
 
     pCapturedSamples = pNewCapturedSamples;
     capturedSampleCount = newCapturedSampleCount;
+
+    (void)pOutput;
 }
 
-mal_uint32 on_send_frames(mal_device* pDevice, mal_uint32 frameCount, void* pSamples)
+void on_send_frames(mal_device* pDevice, const void* pInput, void* pOutput, mal_uint32 frameCount)
 {
     mal_uint32 samplesToRead = frameCount * pDevice->channels;
     if (samplesToRead > capturedSampleCount-playbackSample) {
@@ -36,26 +38,27 @@ mal_uint32 on_send_frames(mal_device* pDevice, mal_uint32 frameCount, void* pSam
     }
 
     if (samplesToRead == 0) {
-        return 0;
+        return;
     }
 
-    memcpy(pSamples, pCapturedSamples + playbackSample, samplesToRead * sizeof(mal_int16));
+    memcpy(pOutput, pCapturedSamples + playbackSample, samplesToRead * sizeof(mal_int16));
     playbackSample += samplesToRead;
 
-    return samplesToRead / pDevice->channels;
+    (void)pInput;
 }
 
 int main()
 {
+    mal_device_config config;
+
     mal_context context;
     if (mal_context_init(NULL, 0, NULL, &context) != MAL_SUCCESS) {
         printf("Failed to initialize context.");
         return -1;
     }
 
-    mal_device_config config = mal_device_config_init(mal_format_s16, 2, 48000, on_recv_frames, on_send_frames, NULL);
-
     printf("Recording...\n");
+    config = mal_device_config_init(mal_format_s16, 2, 48000, on_recv_frames, NULL);
     mal_device captureDevice;
     if (mal_device_init(&context, mal_device_type_capture, NULL, &config, &captureDevice) != MAL_SUCCESS) {
         mal_context_uninit(&context);
@@ -78,6 +81,7 @@ int main()
 
 
     printf("Playing...\n");
+    config = mal_device_config_init(mal_format_s16, 2, 48000, on_send_frames, NULL);
     mal_device playbackDevice;
     if (mal_device_init(&context, mal_device_type_playback, NULL, &config, &playbackDevice) != MAL_SUCCESS) {
         mal_context_uninit(&context);

examples/simple_playback.c

@@ -11,14 +11,16 @@
 #include <stdio.h>
 
 // This is the function that's used for sending more data to the device for playback.
-mal_uint32 on_send_frames_to_device(mal_device* pDevice, mal_uint32 frameCount, void* pSamples)
+void on_send_frames_to_device(mal_device* pDevice, const void* pInput, void* pOutput, mal_uint32 frameCount)
 {
     mal_decoder* pDecoder = (mal_decoder*)pDevice->pUserData;
     if (pDecoder == NULL) {
-        return 0;
+        return;
     }
 
-    return (mal_uint32)mal_decoder_read_pcm_frames(pDecoder, frameCount, pSamples);
+    mal_decoder_read_pcm_frames(pDecoder, frameCount, pOutput);
+
+    (void)pInput;
 }
 
 int main(int argc, char** argv)
@@ -34,7 +36,7 @@ int main(int argc, char** argv)
         return -2;
     }
 
-    mal_device_config config = mal_device_config_init_playback(
+    mal_device_config config = mal_device_config_init(
         decoder.outputFormat,
         decoder.outputChannels,
         decoder.outputSampleRate,