From 590e378f3a26d3cb10ea97c4443b2fb6d2461d14 Mon Sep 17 00:00:00 2001
From: Christian Semmler <mail@csemmler.com>
Date: Tue, 26 Dec 2023 15:25:35 -0500
Subject: [PATCH] Match MxDSBuffer::CalcBytesRemaining

---
 LEGO1/mxdsbuffer.cpp    | 41 ++++++++++++++++++++---------------------
 LEGO1/mxstreamchunk.cpp |  6 ++++++
 LEGO1/mxstreamchunk.h   |  4 +---
 3 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/LEGO1/mxdsbuffer.cpp b/LEGO1/mxdsbuffer.cpp
index d3e6ad0c..b3e028d8 100644
--- a/LEGO1/mxdsbuffer.cpp
+++ b/LEGO1/mxdsbuffer.cpp
@@ -451,32 +451,31 @@ void MxDSBuffer::AddRef(MxDSChunk* p_chunk)
 MxResult MxDSBuffer::CalcBytesRemaining(MxU8* p_data)
 {
 	MxResult result = FAILURE;
-	MxU8* ptr;
-	MxU32 bytesRead;
-	if (m_mode == MxDSBufferType_Allocate) {
-		if (m_bytesRemaining != 0) {
 
-			if (m_writeOffset == m_bytesRemaining) {
-				bytesRead = (*(MxU32*) p_data) + 8;
-				ptr = p_data;
-			}
-			else {
-				ptr = &p_data[MxStreamChunk::ReturnE() + 8];
-				bytesRead = (*(MxU32*) p_data) - MxStreamChunk::ReturnE();
-			}
+	if (m_mode == MxDSBufferType_Allocate && m_bytesRemaining != 0) {
+		MxU32 bytesRead;
+		MxU8* ptr;
 
-			if (bytesRead <= m_bytesRemaining) {
-				memcpy(m_pBuffer + (m_writeOffset - m_bytesRemaining), ptr, bytesRead);
-				if (m_writeOffset == m_bytesRemaining) {
-					MxU8* buffer = m_pBuffer;
-					buffer[1] = *MxStreamChunk::ReturnPlus18Ptr((MxU32*) buffer) + MxStreamChunk::ReturnE();
-				}
+		if (m_writeOffset == m_bytesRemaining) {
+			bytesRead = *(MxU32*) (p_data + 4) + 8;
+			ptr = p_data;
+		}
+		else {
+			ptr = &p_data[MxStreamChunk::ReturnE() + 8];
+			bytesRead = (*(MxU32*) (p_data + 4)) - MxStreamChunk::ReturnE();
+		}
 
-				result = SUCCESS;
-				m_bytesRemaining = m_bytesRemaining - bytesRead;
-			}
+		if (bytesRead <= m_bytesRemaining) {
+			memcpy(m_pBuffer + m_writeOffset - m_bytesRemaining, ptr, bytesRead);
+
+			if (m_writeOffset == m_bytesRemaining)
+				*(MxU32*) (m_pBuffer + 4) = *MxStreamChunk::IntoPlus18(m_pBuffer) + MxStreamChunk::ReturnE();
+
+			m_bytesRemaining -= bytesRead;
+			result = SUCCESS;
 		}
 	}
+
 	return result;
 }
 
diff --git a/LEGO1/mxstreamchunk.cpp b/LEGO1/mxstreamchunk.cpp
index 389d3abf..0143c06b 100644
--- a/LEGO1/mxstreamchunk.cpp
+++ b/LEGO1/mxstreamchunk.cpp
@@ -79,3 +79,9 @@ MxU16* MxStreamChunk::IntoFlags(MxU8* p_buffer)
 {
 	return (MxU16*) (p_buffer + 8);
 }
+
+// FUNCTION: LEGO1 0x100c31b0
+MxU32* MxStreamChunk::IntoPlus18(MxU8* p_buffer)
+{
+	return (MxU32*) (p_buffer + 18);
+}
diff --git a/LEGO1/mxstreamchunk.h b/LEGO1/mxstreamchunk.h
index 60ceb095..bad7c9cc 100644
--- a/LEGO1/mxstreamchunk.h
+++ b/LEGO1/mxstreamchunk.h
@@ -35,6 +35,7 @@ class MxStreamChunk : public MxDSChunk {
 	void SetBuffer(MxDSBuffer* p_buffer);
 
 	static MxU16* IntoFlags(MxU8* p_buffer);
+	static MxU32* IntoPlus18(MxU8* p_buffer);
 
 	// FUNCTION: LEGO1 0x100c3190
 	static MxU32* ReturnPlus10Ptr(MxU32* p_chunk) { return p_chunk + 10; }
@@ -42,9 +43,6 @@ class MxStreamChunk : public MxDSChunk {
 	// FUNCTION: LEGO1 0x100c31a0
 	static MxU32* ReturnPlus14Ptr(MxU32* p_chunk) { return p_chunk + 14; }
 
-	// FUNCTION: LEGO1 0x100c31b0
-	static MxU32* ReturnPlus18Ptr(MxU32* p_chunk) { return p_chunk + 18; }
-
 private:
 	MxDSBuffer* m_buffer; // 0x1c
 };