improve comment explaining the use of alloca()

diff --git a/libs/ardour/vst_plugin.cc b/libs/ardour/vst_plugin.cc
index 09a6f59e7c5bb956a23816e586034edfd7e1d075..5c9c94bdac9a5d303570bc81729125201bf1f10f 100644 (file)
--- a/libs/ardour/vst_plugin.cc
+++ b/libs/ardour/vst_plugin.cc
@@ -535,8 +535,14 @@ VSTPlugin::connect_and_run (BufferSet& bufs,
        BufferSet& silent_bufs  = _session.get_silent_buffers(bufs_count);
        BufferSet& scratch_bufs = _session.get_scratch_buffers(bufs_count);
 
-       // VC++ doesn't support this C99 extension. Use alloca instead of dynamic
-       // array (rather than std::vector which allocs on the heap)
+       /* VC++ doesn't support the C99 extension that allows 
+
+          typeName foo[variableDefiningSize];
+          
+          Use alloca instead of dynamic array (rather than std::vector which
+          allocs on the heap) because this is realtime code.
+       */
+          
        float** ins = (float**)alloca(_plugin->numInputs*sizeof(float*));
        float** outs = (float**)alloca(_plugin->numInputs*sizeof(float*));