From 5d1d0844e1edf748e0b034df4967017614ad99ba Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 14 Jul 2017 00:28:28 +0900
Subject: [PATCH] Add internal/clock

---
 audio/audio.go          | 12 +++--------
 internal/clock/clock.go | 46 +++++++++++++++++++++++++++++++++++++++++
 internal/loop/run.go    |  9 ++++----
 3 files changed, 54 insertions(+), 13 deletions(-)
 create mode 100644 internal/clock/clock.go

diff --git a/audio/audio.go b/audio/audio.go
index 569a128f0..ecfee624f 100644
--- a/audio/audio.go
+++ b/audio/audio.go
@@ -35,6 +35,8 @@ import (
 	"time"
 
 	"github.com/hajimehoshi/oto"
+
+	"github.com/hajimehoshi/ebiten/internal/clock"
 )
 
 const FPS = 60
@@ -222,14 +224,6 @@ func CurrentContext() *Context {
 	return c
 }
 
-// Internal Only?
-func (c *Context) Frame() int64 {
-	c.m.Lock()
-	n := c.framesReadOnly
-	c.m.Unlock()
-	return n
-}
-
 // Internal Only?
 func (c *Context) Ping() {
 	if c.initCh != nil {
@@ -262,7 +256,6 @@ func (c *Context) loop() {
 
 	for {
 		c.m.Lock()
-		c.framesReadOnly = c.frames
 		if c.pingCount == 0 {
 			c.m.Unlock()
 			time.Sleep(10 * time.Millisecond)
@@ -271,6 +264,7 @@ func (c *Context) loop() {
 		c.pingCount--
 		c.m.Unlock()
 		c.frames++
+		clock.Inc()
 		bytesPerFrame := c.sampleRate * bytesPerSample * channelNum / FPS
 		l := (c.frames * int64(bytesPerFrame)) - c.writtenBytes
 		l &= mask
diff --git a/internal/clock/clock.go b/internal/clock/clock.go
new file mode 100644
index 000000000..eee86ed52
--- /dev/null
+++ b/internal/clock/clock.go
@@ -0,0 +1,46 @@
+// Copyright 2017 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package clock
+
+import (
+	"github.com/hajimehoshi/ebiten/internal/sync"
+)
+
+var (
+	m     sync.Mutex
+	valid bool
+	frame int64
+)
+
+func IsValid() bool {
+	m.Lock()
+	v := valid
+	m.Unlock()
+	return v
+}
+
+func Inc() {
+	m.Lock()
+	valid = true
+	frame++
+	m.Unlock()
+}
+
+func Frame() int64 {
+	m.Lock()
+	n := frame
+	m.Unlock()
+	return n
+}
diff --git a/internal/loop/run.go b/internal/loop/run.go
index 43e43518f..06f1d31ed 100644
--- a/internal/loop/run.go
+++ b/internal/loop/run.go
@@ -19,6 +19,7 @@ import (
 	"time"
 
 	"github.com/hajimehoshi/ebiten/audio"
+	"github.com/hajimehoshi/ebiten/internal/clock"
 	"github.com/hajimehoshi/ebiten/internal/sync"
 	"github.com/hajimehoshi/ebiten/internal/ui"
 )
@@ -36,7 +37,7 @@ type runContext struct {
 	framesForFPS   int64
 	lastUpdated    int64
 	lastFPSUpdated int64
-	lastAudioFrame int64
+	lastClockFrame int64
 	m              sync.RWMutex
 }
 
@@ -132,13 +133,13 @@ func (c *runContext) updateCount(now int64) int {
 		return 0
 	}
 
-	if audio.CurrentContext() != nil && c.lastAudioFrame != audio.CurrentContext().Frame() {
+	if clock.IsValid() && c.lastClockFrame != clock.Frame() {
 		sync = true
-		f := audio.CurrentContext().Frame()
+		f := clock.Frame()
 		if c.frames < f {
 			count = int(f - c.frames)
 		}
-		c.lastAudioFrame = f
+		c.lastClockFrame = f
 	} else {
 		count = int(t * int64(c.fps) / int64(time.Second))
 	}