From 764ea3fd2189d73fe41bd0ad4c16490581c1f3b8 Mon Sep 17 00:00:00 2001
From: Stephen Birarda <commit@birarda.com>
Date: Mon, 4 Feb 2013 18:46:24 -0800
Subject: [PATCH] make diffLastWriteNextOutput check for NULL endOfLastWrite

---
 Source/Audio.cpp           | 10 ++--------
 Source/AudioRingBuffer.cpp | 16 ++++++++++------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/Source/Audio.cpp b/Source/Audio.cpp
index 86d153d6fd..374a2d4cb8 100644
--- a/Source/Audio.cpp
+++ b/Source/Audio.cpp
@@ -418,20 +418,14 @@ void Audio::render(int screenWidth, int screenHeight)
         }
         glEnd();
         
-        // show the next audio buffer and end of last write position
-        int scaleLength = currentX - startX;
-        
-        float nextOutputSampleOffset = data->ringBuffer->nextOutput - data->ringBuffer->buffer;
-        
+        // show the next audio buffer and end of last write position        
         float remainingBuffer = 0;
         timeval currentTime;
         gettimeofday(&currentTime, NULL);
         float timeLeftInCurrentBuffer = diffclock(currentTime, data->lastCallback)/(1000.0*(float)BUFFER_LENGTH_SAMPLES/(float)SAMPLE_RATE) * frameWidth;
         //float timeLeftInCurrentBuffer = diffclock(currentTime, data->lastCallback)/23.22 * frameWidth;
         
-        if (data->ringBuffer->endOfLastWrite != NULL) {
-            remainingBuffer = (data->ringBuffer->diffLastWriteNextOutput())/BUFFER_LENGTH_SAMPLES*frameWidth;
-        }
+        remainingBuffer = data->ringBuffer->diffLastWriteNextOutput() / BUFFER_LENGTH_SAMPLES * frameWidth;
         
         glColor3f(1, 0, 0);
         glBegin(GL_QUADS);
diff --git a/Source/AudioRingBuffer.cpp b/Source/AudioRingBuffer.cpp
index 215d2c5ad5..3a34ef7454 100644
--- a/Source/AudioRingBuffer.cpp
+++ b/Source/AudioRingBuffer.cpp
@@ -23,13 +23,17 @@ AudioRingBuffer::~AudioRingBuffer() {
 
 short AudioRingBuffer::diffLastWriteNextOutput()
 {
-    short sampleDifference = endOfLastWrite - nextOutput;
-    
-    if (sampleDifference < 0) {
-        sampleDifference += ringBufferLengthSamples;
+    if (endOfLastWrite == NULL) {
+        return 0;
+    } else {
+        short sampleDifference = endOfLastWrite - nextOutput;
+        
+        if (sampleDifference < 0) {
+            sampleDifference += ringBufferLengthSamples;
+        }
+        
+        return sampleDifference;
     }
-    
-    return sampleDifference;
 }
 
 short AudioRingBuffer::bufferOverlap(int16_t *pointer, short addedDistance)