diff --git a/a8/sysutils.cc b/a8/sysutils.cc
index 9f8cf19..35feec3 100644
--- a/a8/sysutils.cc
+++ b/a8/sysutils.cc
@@ -179,6 +179,12 @@ namespace a8
         return time_t((time_val + g_time_zone * 3600)/3600/24 + incdays) * 3600 * 24 - 3600 * g_time_zone;
     }
 
+    time_t BetweenDays(time_t time_val1, time_t time_val2)
+    {
+        int g_time_zone = 8;
+        return (time_val1 + g_time_zone*3600)/3600/24 - (time_val2 + g_time_zone*3600)/3600/24;
+    }
+
     long long MakeInt64(int low32, int high32)
     {
         return low32 + ((long long)high32 << 32);
diff --git a/a8/sysutils.h b/a8/sysutils.h
index 834628f..52fabc6 100644
--- a/a8/sysutils.h
+++ b/a8/sysutils.h
@@ -66,6 +66,7 @@ namespace a8
 
     std::string FormatDateTime(time_t time_val);
     time_t GetDaySeconds(time_t time_val, int incdays = 0);
+    time_t BetweenDays(time_t time_val1, time_t time_val2);
 
     long long MakeInt64(int low32, int high32);
     int Low32(long long int64_val);