From 0772341b6afbe0826d5b8efcc566833307747e8a Mon Sep 17 00:00:00 2001
From: Nekokabu <nekokabu@gmail.com>
Date: Sat, 1 Aug 2015 17:48:38 +0900
Subject: [PATCH] Fix DMA Sram access when not word aligned

---
 Source/Project64/N64 System/Mips/Sram.cpp | 135 +++++++++++++++++++++-
 1 file changed, 130 insertions(+), 5 deletions(-)

diff --git a/Source/Project64/N64 System/Mips/Sram.cpp b/Source/Project64/N64 System/Mips/Sram.cpp
index 8e642d778..e23e832f0 100644
--- a/Source/Project64/N64 System/Mips/Sram.cpp	
+++ b/Source/Project64/N64 System/Mips/Sram.cpp	
@@ -53,6 +53,8 @@ bool CSram::LoadSram()
 void CSram::DmaFromSram(BYTE * dest, int StartOffset, int len)
 {
 	DWORD dwRead;
+	DWORD i;
+	BYTE tmp[4];
 
 	if (m_hFile == NULL)
 	{
@@ -61,13 +63,76 @@ void CSram::DmaFromSram(BYTE * dest, int StartOffset, int len)
 			return;
 		}
 	}
-	SetFilePointer(m_hFile,StartOffset,NULL,FILE_BEGIN);	
-	ReadFile(m_hFile,dest,len,&dwRead,NULL);
+	DWORD Offset = StartOffset & 3;
 
+	if (Offset == 0)
+	{
+		SetFilePointer(m_hFile, StartOffset, NULL, FILE_BEGIN);
+		ReadFile(m_hFile, dest, len, &dwRead, NULL);
+	}
+	else
+	{
+		SetFilePointer(m_hFile, StartOffset - Offset, NULL, FILE_BEGIN);
+
+		ReadFile(m_hFile, tmp, 4, &dwRead, NULL);
+		for (i = 0; i < (4 - Offset); i++)
+		{
+			dest[i + Offset] = tmp[i];
+		}
+		for (i = 4 - Offset; i < len - Offset; i += 4)
+		{
+			ReadFile(m_hFile, tmp, 4, &dwRead, NULL);
+			switch (Offset)
+			{
+			case 1:
+				dest[i + 2] = tmp[0];
+				dest[i + 3] = tmp[1];
+				dest[i + 4] = tmp[2];
+				dest[i - 3] = tmp[3];
+				break;
+			case 2:
+				dest[i + 4] = tmp[0];
+				dest[i + 5] = tmp[1];
+				dest[i - 2] = tmp[2];
+				dest[i - 1] = tmp[3];
+				break;
+			case 3:
+				dest[i + 6] = tmp[0];
+				dest[i - 1] = tmp[1];
+				dest[i] = tmp[2];
+				dest[i + 1] = tmp[3];
+				break;
+			default:
+				break;
+			}
+		}
+		ReadFile(m_hFile, tmp, 4, &dwRead, NULL);
+		switch (Offset)
+		{
+		case 1:
+			dest[i - 3] = tmp[3];
+			break;
+		case 2:
+			dest[i - 2] = tmp[2];
+			dest[i - 1] = tmp[3];
+			break;
+		case 3:
+			dest[i - 1] = tmp[1];
+			dest[i] = tmp[2];
+			dest[i + 1] = tmp[3];
+			break;
+		default:
+			break;
+		}
+	}
 }
 
 void CSram::DmaToSram(BYTE * Source, int StartOffset, int len)
 {
+	DWORD dwWritten;
+	DWORD i;
+	BYTE tmp[4];
+
 	if (m_ReadOnly)
 	{
 		return;
@@ -80,8 +145,68 @@ void CSram::DmaToSram(BYTE * Source, int StartOffset, int len)
 			return;
 		}
 	}
-	DWORD dwWritten;
-	SetFilePointer(m_hFile,StartOffset,NULL,FILE_BEGIN);	
-	WriteFile(m_hFile,Source,len,&dwWritten,NULL);
+	DWORD Offset = StartOffset & 3;
+	if (Offset == 0)
+	{
+		SetFilePointer(m_hFile, StartOffset, NULL, FILE_BEGIN);
+		WriteFile(m_hFile, Source, len, &dwWritten, NULL);
+	}
+	else
+	{
+		for (i = 0; i < (4 - Offset); i++)
+		{
+			tmp[i] = Source[i + Offset];
+		}
+		SetFilePointer(m_hFile, StartOffset - Offset, NULL, FILE_BEGIN);
+		WriteFile(m_hFile, tmp, (4 - Offset), &dwWritten, NULL);
+
+		SetFilePointer(m_hFile, Offset, NULL, FILE_CURRENT);
+		for (i = 4 - Offset; i < len - Offset; i += 4)
+		{
+			switch (Offset)
+			{
+			case 1:
+				tmp[0] = Source[i + 2];
+				tmp[1] = Source[i + 3];
+				tmp[2] = Source[i + 4];
+				tmp[3] = Source[i - 3];
+				break;
+			case 2:
+				tmp[0] = Source[i + 4];
+				tmp[1] = Source[i + 5];
+				tmp[2] = Source[i - 2];
+				tmp[3] = Source[i - 1];
+				break;
+			case 3:
+				tmp[0] = Source[i + 6];
+				tmp[1] = Source[i - 1];
+				tmp[2] = Source[i];
+				tmp[3] = Source[i + 1];
+				break;
+			default:
+				break;
+			}
+			WriteFile(m_hFile, tmp, 4, &dwWritten, NULL);
+		}
+		switch (Offset)
+		{
+		case 1:
+			tmp[0] = Source[i - 3];
+			break;
+		case 2:
+			tmp[0] = Source[i - 2];
+			tmp[0] = Source[i - 1];
+			break;
+		case 3:
+			tmp[0] = Source[i - 1];
+			tmp[0] = Source[i];
+			tmp[0] = Source[i + 1];
+			break;
+		default:
+			break;
+		}
+		SetFilePointer(m_hFile, 4 - Offset, NULL, FILE_CURRENT);
+		WriteFile(m_hFile, tmp, Offset, &dwWritten, NULL);
+	}
 	FlushFileBuffers(m_hFile);
 }