Add simple_duplex example and remove old duplex text.

Duplex can be tested with the deviceio test.

examples/simple_duplex.c

@@ -0,0 +1,62 @@
+#define MINIAUDIO_IMPLEMENTATION
+#include "../miniaudio.h"
+
+#define DR_WAV_IMPLEMENTATION
+#include "../extras/dr_wav.h"
+
+#include <stdio.h>
+
+#ifdef __EMSCRIPTEN__
+void main_loop__em()
+{
+}
+#endif
+
+void data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount)
+{
+    MA_ASSERT(pDevice->capture.format == pDevice->playback.format);
+    MA_ASSERT(pDevice->capture.channels == pDevice->playback.channels);
+
+    /* In this example the format and channel count are the same for both input and output which means we can just memcpy(). */
+    MA_COPY_MEMORY(pOutput, pInput, frameCount * ma_get_bytes_per_frame(pDevice->capture.format, pDevice->capture.channels));
+}
+
+int main(int argc, char** argv)
+{
+    ma_result result;
+    ma_device_config deviceConfig;
+    ma_device device;
+
+    deviceConfig = ma_device_config_init(ma_device_type_duplex);
+    deviceConfig.capture.pDeviceID  = NULL;
+    deviceConfig.capture.format     = ma_format_s16;
+    deviceConfig.capture.channels   = 2;
+    deviceConfig.capture.shareMode  = ma_share_mode_shared;
+    deviceConfig.playback.pDeviceID = NULL;
+    deviceConfig.playback.format    = ma_format_s16;
+    deviceConfig.playback.channels  = 2;
+    deviceConfig.dataCallback       = data_callback;
+    result = ma_device_init(NULL, &deviceConfig, &device);
+    if (result != MA_SUCCESS) {
+        return result;
+    }
+
+#ifdef __EMSCRIPTEN__
+    getchar();
+#endif
+
+    ma_device_start(&device);
+
+#ifdef __EMSCRIPTEN__
+    emscripten_set_main_loop(main_loop__em, 0, 1);
+#else
+    printf("Press Enter to quit...\n");
+    getchar();
+#endif
+
+    ma_device_uninit(&device);
+
+    (void)argc;
+    (void)argv;
+    return 0;
+}