From 098300bb51d97ae7c037c61964bcd7969e3b20b5 Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Sat, 25 Feb 2023 10:03:03 +0100
Subject: [PATCH] Use mmapping when reading Nasal scripts saving two memory
 copies out of for (copy from disk to the i/o buffer, copy from the i/o buffer
 tot the ifstream, copy from the ifstreamto a string and copy from a string to
 Nasal).

---
 src/Scripting/NasalSys.cxx | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/Scripting/NasalSys.cxx b/src/Scripting/NasalSys.cxx
index 59b01b3b5..8bef6c916 100644
--- a/src/Scripting/NasalSys.cxx
+++ b/src/Scripting/NasalSys.cxx
@@ -47,6 +47,7 @@
 #include <simgear/props/props.hxx>
 #include <simgear/structure/commands.hxx>
 #include <simgear/structure/event_mgr.hxx>
+#include <simgear/io/sg_mmap.hxx>
 
 #include <simgear/nasal/cppbind/from_nasal.hxx>
 #include <simgear/nasal/cppbind/to_nasal.hxx>
@@ -1505,6 +1506,15 @@ bool FGNasalSys::loadModule(SGPath file, const char* module)
         return false;
     }
 
+#if 1
+    // MMap the contents of the file.
+    // This saves an alloc, memcpy and free
+    SGMMapFile mmap(file);
+    mmap.open(SG_IO_IN);
+
+    auto pathStr = file.utf8Str();
+    return createModule(module, pathStr.c_str(), mmap.get(), mmap.get_size());
+#else
     sg_ifstream file_in(file);
     string buf;
     while (!file_in.eof()) {
@@ -1515,6 +1525,7 @@ bool FGNasalSys::loadModule(SGPath file, const char* module)
     file_in.close();
     auto pathStr = file.utf8Str();
     return createModule(module, pathStr.c_str(), buf.data(), buf.length());
+#endif
 }
 
 // Parse and run.  Save the local variables namespace, as it will