Add a Loop source.

modules/audio-libsoundio/include/moon/audio/libsoundio/handle.hxx

@@ -7,6 +7,7 @@
 #include "moon/audio/libsoundio/source.hxx"
 #include "moon/audio/libsoundio/music.hxx"
 #include "moon/audio/libsoundio/sound.hxx"
+#include "moon/audio/libsoundio/loop.hxx"
 
 namespace Moon {
   class Handle {

modules/audio-libsoundio/include/moon/audio/libsoundio/loop.hxx

@@ -0,0 +1,29 @@
+#ifndef MOON_AUDIO_LIBSOUNDIO_LOOP_H
+#define MOON_AUDIO_LIBSOUNDIO_LOOP_H
+
+#include "moon/intern.h"
+#include <string>
+#include <sndfile.hh>
+#include "moon/audio/libsoundio/source.hxx"
+#include "moon/audio/libsoundio/mixer.hxx"
+
+namespace Moon
+{
+  class Loop : public Source {
+    public:
+      Loop(Moon::Source* source, std::uint32_t trigger, std::uint32_t target);
+      virtual ~Loop();
+
+      int read(float* dst, int frames);
+      std::uint32_t seek(std::uint32_t pos);
+
+      int channels();
+      int sampleRate();
+    private:
+      std::uint32_t trigger;
+      std::uint32_t target;
+      Moon::Source* source; // TODO:mrb_sound/music sources will need to be wrapped... if a source deallocates, the handle will be broken (shared_ptr)
+  };
+};
+
+#endif

modules/audio-libsoundio/include/moon/audio/libsoundio/source.hxx

@@ -8,8 +8,8 @@ namespace Moon
   class Source {
     public:
       virtual int read(float* dst, int frames) = 0;
-      virtual std:uint32_t seek(std::uint32_t pos);
-      virtual int tell() { return seek(0); };
+      virtual std::uint32_t seek(std::uint32_t pos);
+      virtual std::uint32_t tell() { return seek(0); };
       //
       virtual int channels() = 0;
       virtual int sampleRate() = 0;

modules/audio-libsoundio/src/loop.cxx

@@ -0,0 +1,47 @@
+#include "moon/intern.h"
+#include "moon/audio/libsoundio/music.hxx"
+
+namespace Moon
+{
+  Loop::Loop(Moon::Source* source, std::uint32_t trigger, std::uint32_t target) {
+    this->source = source;
+    this->trigger = trigger;
+    this->target = target;
+
+    // TODO: bounds checking (trigger/target being further than file length)
+  };
+
+  Loop::~Loop() {
+  }
+
+  int Loop::channels() {
+    return source->channels();
+  }
+
+  int Loop::sampleRate() {
+    return source->sampleRate();
+  }
+
+  // returns how many frames we actually read
+  int Loop::read(float* dst, int frames)
+  {
+    std::uint32_t current = source->tell();
+    std::uint32_t diff = trigger - current;
+
+    // frames fit without seeking
+    if (frames <= diff) {
+      return source->read(dst, frames);
+    } else { // we need to read then seek
+      source->read(dst, diff);
+      source->seek(target);
+      dst += diff * source->channels();
+      source->read(dst, frames);
+    }
+    return frames;
+  }
+
+  // seeks to a given offset (in frames) from the start of the file
+  std::uint32_t Loop::seek(std::uint32_t pos) {
+    return source->seek(pos);
+  }
+}