From ae41ad5d1ed2c9b41cf5bbb7aa78848a043ee1f8 Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Mon, 2 Aug 2010 20:04:52 -0700
Subject: Use a better method to time the Null and Wave Writer backends This
 better compensates for precision loss when converting milliseconds to the
 sample rate

---
 Alc/wave.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

(limited to 'Alc/wave.c')

diff --git a/Alc/wave.c b/Alc/wave.c
index 1b6a41d1..5f1f399b 100644
--- a/Alc/wave.c
+++ b/Alc/wave.c
@@ -35,6 +35,8 @@ typedef struct {
     ALvoid *buffer;
     ALuint size;
 
+    ALuint startTime;
+
     volatile int killNow;
     ALvoid *thread;
 } wave_data;
@@ -68,32 +70,42 @@ static ALuint WaveProc(ALvoid *ptr)
     ALCdevice *pDevice = (ALCdevice*)ptr;
     wave_data *data = (wave_data*)pDevice->ExtraData;
     ALuint frameSize;
-    ALuint now, last;
+    ALuint now, start;
+    ALuint64 avail, done;
     size_t fs;
-    ALuint avail;
     union {
         short s;
         char b[sizeof(short)];
     } uSB;
+    const ALuint restTime = (ALuint64)pDevice->UpdateSize * 1000 /
+                            pDevice->Frequency / 2;
 
     uSB.s = 1;
     frameSize = aluFrameSizeFromFormat(pDevice->Format);
 
-    last = timeGetTime()<<8;
+    done = 0;
+    start = data->startTime;
     while(!data->killNow && pDevice->Connected)
     {
-        now = timeGetTime()<<8;
+        now = timeGetTime();
 
-        avail = (ALuint64)(now-last) * pDevice->Frequency / (1000<<8);
-        if(avail < pDevice->UpdateSize)
+        avail = (ALuint64)(now-start) * pDevice->Frequency / 1000;
+        if(avail < done)
+        {
+            AL_PRINT("Timer wrapped\n");
+            aluHandleDisconnect(pDevice);
+            break;
+        }
+        if(avail-done < pDevice->UpdateSize)
         {
-            Sleep(1);
+            Sleep(restTime);
             continue;
         }
 
-        while(avail >= pDevice->UpdateSize)
+        while(avail-done >= pDevice->UpdateSize)
         {
             aluMixData(pDevice, data->buffer, pDevice->UpdateSize);
+            done += pDevice->UpdateSize;
 
             if(uSB.b[0] != 1)
             {
@@ -125,9 +137,6 @@ static ALuint WaveProc(ALvoid *ptr)
                 aluHandleDisconnect(pDevice);
                 break;
             }
-
-            avail -= pDevice->UpdateSize;
-            last += (ALuint64)pDevice->UpdateSize * (1000<<8) / pDevice->Frequency;
         }
     }
 
@@ -277,6 +286,7 @@ static ALCboolean wave_reset_playback(ALCdevice *device)
                       device->Frequency;
     SetDefaultWFXChannelOrder(device);
 
+    data->startTime = timeGetTime();
     data->thread = StartThread(WaveProc, device);
     if(data->thread == NULL)
     {
-- 
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