From 13dd754a8c0113bebc0ad65def80d4caf5fc9b60 Mon Sep 17 00:00:00 2001
From: Alan Mishchenko <alanmi@berkeley.edu>
Date: Tue, 18 Jun 2013 11:26:37 -0700
Subject: [PATCH] Suggested changes to counting time in Abc_Clock()

---
 Makefile                   |  2 +-
 src/misc/util/abc_global.h | 20 ++++++++++----------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/Makefile b/Makefile
index 6db73c5e9..0950b1670 100644
--- a/Makefile
+++ b/Makefile
@@ -62,7 +62,7 @@ endif
 
 endif
 
-LIBS := -ldl
+LIBS := -ldl -lrt
 
 ifneq ($(READLINE),0)
 CFLAGS += -DABC_USE_READLINE
diff --git a/src/misc/util/abc_global.h b/src/misc/util/abc_global.h
index 5d6a8aebe..d9aa9701a 100644
--- a/src/misc/util/abc_global.h
+++ b/src/misc/util/abc_global.h
@@ -271,18 +271,18 @@ static inline int      Abc_Lit2LitL( int * pMap, int Lit )    { return Abc_LitNo
 typedef ABC_INT64_T abctime;
 static inline abctime Abc_Clock()
 {
-    static abctime PeriodNum = 0;
-    static clock_t Period = ((abctime)1 << 30);
-    clock_t ClockTime = clock();
-    if ( ClockTime >= Period )
-    {
-        ClockTime -= Period;
-        PeriodNum++;
-    }
-    return PeriodNum * Period + ClockTime;
+#if defined(LIN) || defined(LIN64)
+    struct timespec ts;
+    if ( clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts) < 0 ) 
+        return (abctime)-1;
+    abctime res = ((abctime) ts.tv_sec) * CLOCKS_PER_SEC;
+    res += (((abctime) ts.tv_nsec) * CLOCKS_PER_SEC) / 1000000000;
+    return res;
+#else
+    return (abctime) clock();
+#endif
 }
 
-
 // bridge communication
 #define BRIDGE_NETLIST           106
 #define BRIDGE_ABS_NETLIST       107