added a test

.gitignore

@@ -1,2 +1,3 @@
 build/
 out/
+.cache

CMakeLists.txt

@@ -20,6 +20,7 @@ set(BUILD_EXAMPLE_PROGRAMS OFF CACHE BOOL "")
 set(BUILD_DYNAMIC_LIBS ON  CACHE BOOL "" FORCE)
 set(BUILD_STATIC_LIBS  ON  CACHE BOOL "" FORCE)
 
+# libsoundio
 add_subdirectory("${CMAKE_SOURCE_DIR}/extern/libsoundio")
 target_include_directories(${PROJECT_NAME} PRIVATE "${CMAKE_SOURCE_DIR}/extern/libsoundio")
 
@@ -27,3 +28,6 @@ target_link_libraries(${PROJECT_NAME} PRIVATE
   $<$<CONFIG:Debug>:libsoundio_shared>
   $<$<CONFIG:Release>:libsoundio_static>
 )
+
+# math
+target_link_libraries(${PROJECT_NAME} PRIVATE m)

compile_commands.json

@@ -0,0 +1 @@
+build/compile_commands.json

src/main.c

@@ -1,8 +1,108 @@
+#include <soundio/soundio.h>
+
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
 
-int
+static const float PI = 3.1415926535f;
-main(int argc, char *argv[]) {
+static float seconds_offset = 0.0f;
-    printf("Hello, %s\n", argv[0]);
+static void write_callback(struct SoundIoOutStream *outstream,
+        int frame_count_min, int frame_count_max)
+{
+    const struct SoundIoChannelLayout *layout = &outstream->layout;
+    float float_sample_rate = outstream->sample_rate;
+    float seconds_per_frame = 1.0f / float_sample_rate;
+    struct SoundIoChannelArea *areas;
+    int frames_left = frame_count_max;
+    int err;
 
+    while (frames_left > 0) {
+        int frame_count = frames_left;
+
+        if ((err = soundio_outstream_begin_write(outstream, &areas, &frame_count))) {
+            fprintf(stderr, "%s\n", soundio_strerror(err));
+            exit(1);
+        }
+
+        if (!frame_count)
+            break;
+
+        float pitch = 440.0f;
+        float radians_per_second = pitch * 2.0f * PI;
+        for (int frame = 0; frame < frame_count; frame += 1) {
+            float sample = sin((seconds_offset + frame * seconds_per_frame) * radians_per_second);
+            for (int channel = 0; channel < layout->channel_count; channel += 1) {
+                float *ptr = (float*)(areas[channel].ptr + areas[channel].step * frame);
+                *ptr = sample;
+            }
+        }
+        seconds_offset = fmod(seconds_offset + seconds_per_frame * frame_count, 1.0);
+
+        if ((err = soundio_outstream_end_write(outstream))) {
+            fprintf(stderr, "%s\n", soundio_strerror(err));
+            exit(1);
+        }
+
+        frames_left -= frame_count;
+    }
+}
+
+int main(int argc, char **argv) {
+    int err;
+    struct SoundIo *soundio = soundio_create();
+    if (!soundio) {
+        fprintf(stderr, "out of memory\n");
+        return 1;
+    }
+
+    if ((err = soundio_connect(soundio))) {
+        fprintf(stderr, "error connecting: %s\n", soundio_strerror(err));
+        return 1;
+    }
+
+    soundio_flush_events(soundio);
+
+    int default_out_device_index = soundio_default_output_device_index(soundio);
+    if (default_out_device_index < 0) {
+        fprintf(stderr, "no output device found\n");
+        return 1;
+    }
+
+    struct SoundIoDevice *device = soundio_get_output_device(soundio, default_out_device_index);
+    if (!device) {
+        fprintf(stderr, "out of memory\n");
+        return 1;
+    }
+
+    fprintf(stderr, "Output device: %s\n", device->name);
+
+    struct SoundIoOutStream *outstream = soundio_outstream_create(device);
+    if (!outstream) {
+        fprintf(stderr, "out of memory\n");
+        return 1;
+    }
+    outstream->format = SoundIoFormatFloat32NE;
+    outstream->write_callback = write_callback;
+
+    if ((err = soundio_outstream_open(outstream))) {
+        fprintf(stderr, "unable to open device: %s", soundio_strerror(err));
+        return 1;
+    }
+
+    if (outstream->layout_error)
+        fprintf(stderr, "unable to set channel layout: %s\n", soundio_strerror(outstream->layout_error));
+
+    if ((err = soundio_outstream_start(outstream))) {
+        fprintf(stderr, "unable to start device: %s\n", soundio_strerror(err));
+        return 1;
+    }
+
+    for (;;)
+        soundio_wait_events(soundio);
+
+    soundio_outstream_destroy(outstream);
+    soundio_device_unref(device);
+    soundio_destroy(soundio);
     return 0;
 }