add millisecond resolution timer (#1234)

Co-authored-by: Aidan Lee <[email protected]>

Author: Aidan63

include/hx/StdLibs.h

@@ -43,6 +43,7 @@ Array<unsigned char> __hxcpp_resource_bytes(String inName);
 // System access
 Array<String>  __get_args();
 double         __time_stamp();
+::cpp::Int64   __time_stamp_ms();
 
 HXCPP_EXTERN_CLASS_ATTRIBUTES void __hxcpp_print_string(const String &inV);
 HXCPP_EXTERN_CLASS_ATTRIBUTES void __hxcpp_println_string(const String &inV);

src/hx/StdLibs.cpp

@@ -242,8 +242,17 @@ int __hxcpp_irand(int inMax)
    return (lo | (mid<<12) | (hi<<24) ) % inMax;
 }
 
+#ifdef HX_WINDOWS
+LARGE_INTEGER qpcFrequency;
+#endif
+
 void __hxcpp_stdlibs_boot()
 {
+#ifdef HX_WINDOWS
+    // MSDN states that QueryPerformanceFrequency will always succeed on XP and above, so I'm ignoring the result.
+    QueryPerformanceFrequency(&qpcFrequency);
+#endif
+
    #if defined(_MSC_VER) && !defined(HX_WINRT)
    HMODULE kernel32 = LoadLibraryA("kernel32");
    if (kernel32)
@@ -327,10 +336,7 @@ double  __time_stamp()
       if (t0==0)
       {
          t0 = now;
-         __int64 freq;
-         QueryPerformanceFrequency((LARGE_INTEGER*)&freq);
-         if (freq!=0)
-            period = 1.0/freq;
+         period = 1.0/qpcFrequency.QuadPart;
       }
       if (period!=0)
          return (now-t0)*period;
@@ -349,6 +355,26 @@ double  __time_stamp()
 #endif
 }
 
+::cpp::Int64 __time_stamp_ms()
+{
+#ifdef HX_WINDOWS
+    // MSDN states that QueryPerformanceCounter will always succeed on XP and above, so I'm ignoring the result.
+    auto now = LARGE_INTEGER{ 0 };
+    QueryPerformanceCounter(&now);
+
+    return now.QuadPart * LONGLONG{ 1000 } / qpcFrequency.QuadPart;
+#else
+    auto time = timespec();
+
+    if (clock_gettime(CLOCK_MONOTONIC, &time))
+    {
+        throw ::Dynamic(HX_CSTRING("Failed to get the monotonic clock time"));
+    }
+
+    return time.tv_sec * 1000 + (time.tv_nsec / 1000000);
+#endif
+}
+
 #if defined(HX_WINDOWS) && !defined(HX_WINRT)
 
 /*