X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fpbd%2Fwindows_timer_utils.cc;h=0fab935b082e5f0c4709e16040fd360e16b085d7;hb=cf52d6e4b40111eb04b244ec054055a4ec15dbe0;hp=d95a69e0c71b47373a7a55d5225bfa62d0b9381d;hpb=a88b2da6a90b1d6f3004333a89761d312b02cf37;p=ardour.git

diff --git a/libs/pbd/windows_timer_utils.cc b/libs/pbd/windows_timer_utils.cc
index d95a69e0c7..0fab935b08 100644
--- a/libs/pbd/windows_timer_utils.cc
+++ b/libs/pbd/windows_timer_utils.cc
@@ -23,11 +23,15 @@
 
 #include "pbd/compose.h"
 #include "pbd/debug.h"
+#include "pbd/error.h"
+
+#include "pbd/i18n.h"
 
 #define DEBUG_TIMING(msg) DEBUG_TRACE (PBD::DEBUG::Timing, msg);
 
 namespace {
 
+static
 UINT&
 timer_resolution ()
 {
@@ -35,7 +39,7 @@ timer_resolution ()
 	return timer_res_ms;
 }
 
-}
+} // namespace
 
 namespace PBD {
 
@@ -100,6 +104,7 @@ reset_resolution ()
 		DEBUG_TIMING("Could not reset the Timer resolution.\n");
 		return false;
 	}
+	DEBUG_TIMING("Reset the Timer resolution.\n");
 	timer_resolution() = 0;
 	return true;
 }
@@ -108,32 +113,23 @@ reset_resolution ()
 
 namespace {
 
-bool&
-qpc_frequency_success ()
-{
-	static bool success = false;
-	return success;
-}
+static double timer_rate_us = 0.0;
 
-LARGE_INTEGER
-qpc_frequency ()
+static
+bool
+test_qpc_validity ()
 {
-	LARGE_INTEGER freq;
-	if (QueryPerformanceFrequency(&freq) == 0) {
-		DEBUG_TIMING ("Failed to determine frequency of QPC\n");
-		qpc_frequency_success() = false;
-	} else {
-		qpc_frequency_success() = true;
+	int64_t last_timer_val = PBD::QPC::get_microseconds ();
+	if (last_timer_val < 0) return false;
+
+	for (int i = 0; i < 100000; ++i) {
+		int64_t timer_val = PBD::QPC::get_microseconds ();
+		if (timer_val < 0) return false;
+		// try and test for non-syncronized TSC(AMD K8/etc)
+		if (timer_val < last_timer_val) return false;
+		last_timer_val = timer_val;
 	}
-
-	return freq;
-}
-
-LARGE_INTEGER
-qpc_frequency_cached ()
-{
-	static LARGE_INTEGER frequency = qpc_frequency ();
-	return frequency;
+	return true;
 }
 
 } // anon namespace
@@ -141,11 +137,27 @@ qpc_frequency_cached ()
 namespace QPC {
 
 bool
-get_timer_valid ()
+check_timer_valid ()
+{
+	if (!timer_rate_us) {
+		return false;
+	}
+	return test_qpc_validity ();
+}
+
+bool
+initialize ()
 {
-	// setup caching the timer frequency
-	qpc_frequency_cached ();
-	return qpc_frequency_success ();
+	LARGE_INTEGER freq;
+	if (!QueryPerformanceFrequency(&freq) || freq.QuadPart < 1) {
+		info << X_("Failed to determine frequency of QPC\n") << endmsg;
+		timer_rate_us = 0;
+	} else {
+		timer_rate_us = 1000000.0 / freq.QuadPart;
+	}
+	info << string_compose(X_("QPC timer microseconds per tick: %1\n"),
+	                       timer_rate_us) << endmsg;
+	return !timer_rate_us;
 }
 
 int64_t
@@ -153,12 +165,11 @@ get_microseconds ()
 {
 	LARGE_INTEGER current_val;
 
-	if (qpc_frequency_success()) {
+	if (timer_rate_us) {
 		// MS docs say this will always succeed for systems >= XP but it may
 		// not return a monotonic value with non-invariant TSC's etc
 		if (QueryPerformanceCounter(&current_val) != 0) {
-			return (int64_t)(((double)current_val.QuadPart) /
-			                 ((double)qpc_frequency_cached().QuadPart) * 1000000.0);
+			return (int64_t)(current_val.QuadPart * timer_rate_us);
 		}
 	}
 	DEBUG_TIMING ("Could not get QPC timer\n");
@@ -170,7 +181,7 @@ get_microseconds ()
 int64_t
 get_microseconds ()
 {
-	if (qpc_frequency_success()) {
+	if (timer_rate_us) {
 		return QPC::get_microseconds ();
 	}
 	// For XP systems that don't support a high-res performance counter