From 073360a19a86985f1ace1b70e2a07ad2744bfda1 Mon Sep 17 00:00:00 2001
From: Brad Lassey <blassey@mozilla.com>
Date: Thu, 16 Apr 2009 12:03:56 -0400
Subject: [PATCH] bug 487515 - PRMJ_Now needs better granularity for panning in
 fennec r=crowder, robarnold

---
 js/src/prmjtime.cpp | 67 +++++++++++++++++++++++++++++----------------
 js/src/prmjtime.h   |  2 +-
 2 files changed, 45 insertions(+), 24 deletions(-)

diff --git a/js/src/prmjtime.cpp b/js/src/prmjtime.cpp
index f1e340ee1c1..c0431a74a18 100644
--- a/js/src/prmjtime.cpp
+++ b/js/src/prmjtime.cpp
@@ -165,10 +165,25 @@ static const JSInt64 win2un = JSLL_INIT(0x19DB1DE, 0xD53E8000);
 
 #endif
 
-#ifdef HAVE_GETSYSTEMTIMEASFILETIME
+#if defined(HAVE_GETSYSTEMTIMEASFILETIME) || defined(HAVE_SYSTEMTIMETOFILETIME)
 
-typedef struct CalibrationData
+#if defined(HAVE_GETSYSTEMTIMEASFILETIME)
+inline void
+LowResTime(LPFILETIME lpft)
+{ 
+    GetSystemTimeAsFileTime(lpft); 
+}
+#elif defined(HAVE_SYSTEMTIMETOFILETIME)
+inline void
+LowResTime(LPFILETIME lpft)
 {
+    GetCurrentFT(lpft);
+}
+#else
+#error "No implementation of PRMJ_Now was selected."
+#endif
+
+typedef struct CalibrationData {
     long double freq;         /* The performance counter frequency */
     long double offset;       /* The low res 'epoch' */
     long double timer_offset; /* The high res 'epoch' */
@@ -182,6 +197,9 @@ typedef struct CalibrationData
     CRITICAL_SECTION data_lock;
     CRITICAL_SECTION calibration_lock;
 #endif
+#ifdef WINCE
+    JSInt64 granularity;
+#endif
 } CalibrationData;
 
 static CalibrationData calibration = { 0 };
@@ -206,12 +224,16 @@ NowCalibrate()
         /* By wrapping a timeBegin/EndPeriod pair of calls around this loop,
            the loop seems to take much less time (1 ms vs 15ms) on Vista. */
         timeBeginPeriod(1);
-        GetSystemTimeAsFileTime(&ftStart);
+        LowResTime(&ftStart);
         do {
-            GetSystemTimeAsFileTime(&ft);
+            LowResTime(&ft);
         } while (memcmp(&ftStart,&ft, sizeof(ft)) == 0);
         timeEndPeriod(1);
-
+        
+#ifdef WINCE
+        calibration.granularity = (FILETIME2INT64(ft) - 
+                                   FILETIME2INT64(ftStart))/10;
+#endif
         /*
         calibrationDelta = (FILETIME2INT64(ft) - FILETIME2INT64(ftStart))/10;
         fprintf(stderr, "Calibration delta was %I64d us\n", calibrationDelta);
@@ -243,8 +265,13 @@ NowInit(void)
 {
     memset(&calibration, 0, sizeof(calibration));
     NowCalibrate();
+#ifdef WINCE
+    InitializeCriticalSection(&calibration.calibration_lock);
+    InitializeCriticalSection(&calibration.data_lock);
+#else
     InitializeCriticalSectionAndSpinCount(&calibration.calibration_lock, CALIBRATIONLOCK_SPINCOUNT);
     InitializeCriticalSectionAndSpinCount(&calibration.data_lock, DATALOCK_SPINCOUNT);
+#endif
     return PR_SUCCESS;
 }
 
@@ -258,7 +285,11 @@ PRMJ_NowShutdown()
 #define MUTEX_LOCK(m) EnterCriticalSection(m)
 #define MUTEX_TRYLOCK(m) TryEnterCriticalSection(m)
 #define MUTEX_UNLOCK(m) LeaveCriticalSection(m)
+#ifdef WINCE
+#define MUTEX_SETSPINCOUNT(m, c)
+#else
 #define MUTEX_SETSPINCOUNT(m, c) SetCriticalSectionSpinCount((m),(c))
+#endif
 
 static PRCallOnceType calibrationOnce = { 0 };
 
@@ -312,7 +343,7 @@ PRMJ_Now(void)
     return s;
 }
 
-#elif defined(HAVE_GETSYSTEMTIMEASFILETIME)
+#else
 /*
 
 Win32 python-esque pseudo code
@@ -395,7 +426,7 @@ PRMJ_Now(void)
     int thiscall = JS_ATOMIC_INCREMENT(&nCalls);
     /* 10 seems to be the number of calls to load with a blank homepage */
     if (thiscall <= 10) {
-        GetSystemTimeAsFileTime(&ft);
+        LowResTime(&ft);
         return (FILETIME2INT64(ft)-win2un)/10L;
     }
 
@@ -427,7 +458,7 @@ PRMJ_Now(void)
 
 
         /* Calculate a low resolution time */
-        GetSystemTimeAsFileTime(&ft);
+        LowResTime(&ft);
         lowresTime = 0.1*(long double)(FILETIME2INT64(ft) - win2un);
 
         if (calibration.freq > 0.0) {
@@ -453,6 +484,10 @@ PRMJ_Now(void)
             returnedTime = calibration.last;
             MUTEX_UNLOCK(&calibration.data_lock);
 
+#ifdef WINCE
+            /* Get an estimate of clock ticks per second from our own test */
+            skewThreshold = calibration.granularity;
+#else
             /* Rather than assume the NT kernel ticks every 15.6ms, ask it */
             if (GetSystemTimeAdjustment(&timeAdjustment,
                                         &timeIncrement,
@@ -465,7 +500,7 @@ PRMJ_Now(void)
                     skewThreshold = timeIncrement/10.0;
                 }
             }
-
+#endif
             /* Check for clock skew */
             diff = lowresTime - highresTime;
 
@@ -514,20 +549,6 @@ PRMJ_Now(void)
 
     return returnedTime;
 }
-
-#elif defined (HAVE_SYSTEMTIMETOFILETIME)
-JSInt64
-PRMJ_Now(void)
-{
-    FILETIME ft;
-    SYSTEMTIME st;
-    GetSystemTime(&st);
-    SystemTimeToFileTime(&st,&ft);
-    return (FILETIME2INT64(ft)-win2un)/10L;
-}
-
-#else
-#error "No implementation of PRMJ_Now was selected."
 #endif
 
 /* Get the DST timezone offset for the time passed in */
diff --git a/js/src/prmjtime.h b/js/src/prmjtime.h
index 9005ef82351..2ff07eb378f 100644
--- a/js/src/prmjtime.h
+++ b/js/src/prmjtime.h
@@ -78,7 +78,7 @@ extern JSInt64
 PRMJ_Now(void);
 
 /* Release the resources associated with PRMJ_Now; don't call PRMJ_Now again */
-#if defined(JS_THREADSAFE) && defined(HAVE_GETSYSTEMTIMEASFILETIME)
+#if defined(JS_THREADSAFE) && (defined(HAVE_GETSYSTEMTIMEASFILETIME) || defined(HAVE_SYSTEMTIMETOFILETIME))
 extern void
 PRMJ_NowShutdown(void);
 #else