+#if HAVE_SYSCTL && defined HW_PHYSMEM
+ { /* This works on *bsd and darwin. */
+ unsigned int physmem;
+ size_t len = sizeof physmem;
+ static int mib[2] = { CTL_HW, HW_PHYSMEM };
+
+ if (sysctl (mib, ARRAY_SIZE (mib), &physmem, &len, NULL, 0) == 0
+ && len == sizeof (physmem))
+ return (double) physmem;
+ }
+#endif
+
+#if HAVE__SYSTEM_CONFIGURATION
+ /* This works on AIX 4.3.3+. */
+ return _system_configuration.physmem;
+#endif
+
+#if defined _WIN32
+ { /* this works on windows */
+ PFN_MS_EX pfnex;
+ HMODULE h = GetModuleHandle ("kernel32.dll");
+
+ if (!h)
+ return 0.0;
+
+ /* Use GlobalMemoryStatusEx if available. */
+ if ((pfnex = (PFN_MS_EX) GetProcAddress (h, "GlobalMemoryStatusEx")))
+ {
+ lMEMORYSTATUSEX lms_ex;
+ lms_ex.dwLength = sizeof lms_ex;
+ if (!pfnex (&lms_ex))
+ return 0.0;
+ return (double) lms_ex.ullTotalPhys;
+ }
+
+ /* Fall back to GlobalMemoryStatus which is always available.
+ but returns wrong results for physical memory > 4GB. */
+ else
+ {
+ MEMORYSTATUS ms;
+ GlobalMemoryStatus (&ms);
+ return (double) ms.dwTotalPhys;
+ }
+ }
+#endif
+