From 161ddbeac095e06c1788fbe114b0ca57fdf8d0e2 Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Sun, 28 Feb 2021 08:56:08 -0800
Subject: [PATCH] Mpeg: Allow full use of the buffer queue.

Track filled size separately so we can be entirely filled.
---
 Core/HW/BufferQueue.cpp |  9 ++++++++-
 Core/HW/BufferQueue.h   | 29 ++++++++++++++++++++---------
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/Core/HW/BufferQueue.cpp b/Core/HW/BufferQueue.cpp
index 9fbffe0c65..19dc2abd00 100644
--- a/Core/HW/BufferQueue.cpp
+++ b/Core/HW/BufferQueue.cpp
@@ -20,7 +20,7 @@
 #include "Core/HW/BufferQueue.h"
 
 void BufferQueue::DoState(PointerWrap &p) {
-	auto s = p.Section("BufferQueue", 0, 1);
+	auto s = p.Section("BufferQueue", 0, 2);
 
 	Do(p, bufQueueSize);
 	Do(p, start);
@@ -31,5 +31,12 @@ void BufferQueue::DoState(PointerWrap &p) {
 
 	if (s >= 1) {
 		Do(p, ptsMarks);
+	} else {
+		ptsMarks.clear();
+	}
+	if (s >= 2) {
+		Do(p, filled);
+	} else {
+		filled = calcQueueSize();
 	}
 }
diff --git a/Core/HW/BufferQueue.h b/Core/HW/BufferQueue.h
index fc0fa1f395..6b950e9071 100644
--- a/Core/HW/BufferQueue.h
+++ b/Core/HW/BufferQueue.h
@@ -38,23 +38,19 @@ struct BufferQueue {
 		if (bufQueue)
 			delete [] bufQueue;
 		bufQueue = new unsigned char[size];
-		start = 0;
-		end = 0;
 		bufQueueSize = size;
+		clear();
 		return true;
 	}
 
 	void clear() {
 		start = 0;
 		end = 0;
+		filled = 0;
 	}
 
 	inline int getQueueSize() {
-		if (end >= start) {
-			return end - start;
-		} else {
-			return bufQueueSize + end - start;
-		}
+		return filled;
 	}
 
 	inline int getRemainSize() {
@@ -63,8 +59,7 @@ struct BufferQueue {
 
 	bool push(const unsigned char *buf, int addsize, s64 pts = 0) {
 		int space = getRemainSize();
-		// We can't fill entirely, or end will equal start and we'll be empty.
-		if (space <= addsize || addsize < 0)
+		if (space < addsize || addsize < 0)
 			return false;
 		savePts(pts);
 		if (end + addsize <= bufQueueSize) {
@@ -81,6 +76,8 @@ struct BufferQueue {
 			memcpy(bufQueue, buf + firstSize, addsize - firstSize);
 			end = addsize - firstSize;
 		}
+		filled += addsize;
+		verifyQueueSize();
 		return true;
 	}
 
@@ -109,6 +106,8 @@ struct BufferQueue {
 			start = bytesgot - firstSize;
 		if (start == bufQueueSize)
 			start = 0;
+		filled -= bytesgot;
+		verifyQueueSize();
 		return bytesgot;
 	}
 
@@ -166,10 +165,22 @@ private:
 		return pts;
 	}
 
+	inline int calcQueueSize() {
+		if (end < start) {
+			return bufQueueSize + end - start;
+		}
+		return end - start;
+	}
+
+	inline void verifyQueueSize() {
+		_assert_(calcQueueSize() == filled || (end == start && filled == bufQueueSize));
+	}
+
 	uint8_t *bufQueue = nullptr;
 	// Model: end may be less than start, indicating the space between end and start is free.
 	// If end equals start, we're empty.
 	int start = 0, end = 0;
+	int filled = 0;
 	int bufQueueSize = 0;
 
 	std::map<u32, s64> ptsMarks;