Don't mandate C++14 as some build daemons still don't have it

[simgrid.git] / src / mc / sosp / PageStore.cpp

diff --git a/src/mc/sosp/PageStore.cpp b/src/mc/sosp/PageStore.cpp
index 21a9ea2..ce53075 100644 (file)
--- a/src/mc/sosp/PageStore.cpp
+++ b/src/mc/sosp/PageStore.cpp
@@ -12,7 +12,9 @@
 #include "xbt/log.h"
 #include "xbt/sysdep.h"
 
+#ifdef SG_HAVE_CPP14
 #include "src/include/xxhash.hpp"
+#endif
 #include "src/mc/mc_mmu.hpp"
 #include "src/mc/sosp/PageStore.hpp"
 
@@ -34,7 +36,18 @@ namespace mc {
  */
 static XBT_ALWAYS_INLINE PageStore::hash_type mc_hash_page(const void* data)
 {
+#ifdef SG_HAVE_CPP14
   return xxh::xxhash<64>(data, xbt_pagesize);
+#else
+  const std::uint64_t* values = (const uint64_t*)data;
+  std::size_t n               = xbt_pagesize / sizeof(uint64_t);
+
+  // This djb2:
+  std::uint64_t hash = 5381;
+  for (std::size_t i = 0; i != n; ++i)
+    hash = ((hash << 5) + hash) + values[i];
+  return hash;
+#endif
 }
 
 // ***** snapshot_page_manager