very, very simple WP with midi CC out

include/libremidi/detail/ump_stream.hpp

@@ -0,0 +1,58 @@
+#pragma once
+#include <libremidi/cmidi2.hpp>
+
+#include <cinttypes>
+#include <cstdint>
+
+namespace libremidi
+{
+enum class segmentation_error
+{
+  no_error,
+  need_space,
+  other
+};
+
+/**
+ * Utility function to segment an ump stream into individual messages.
+ * Used to send a stream to APIs that work message-by-message.
+ */
+inline void
+segment_ump_stream(const uint32_t* ump_stream, int64_t count, auto write_func, auto realloc_func)
+{
+  while (count > 0)
+  {
+    // Handle NOOP (or padding)
+    while (count > 0 && ump_stream[0] == 0)
+    {
+      count--;
+      ump_stream++;
+    }
+
+    if (count == 0)
+      break;
+
+    const auto ump_bytes = cmidi2_ump_get_num_bytes(ump_stream[0]);
+
+    // FIXME std::expected, propagate the error back to caller?
+    switch (write_func(ump_stream, ump_bytes))
+    {
+      case segmentation_error::no_error:
+        break;
+      case segmentation_error::need_space:
+        // Try again if we didn't have enough space in the OS queue
+        realloc_func();
+        if (write_func(ump_stream, ump_bytes) != segmentation_error::no_error)
+          return;
+        break;
+      case segmentation_error::other:
+        return;
+    }
+
+    const auto ump_uints = ump_bytes / 4;
+    ump_stream += ump_uints;
+    count -= ump_uints;
+  }
+}
+
+}