Fixed support for double-sided SSD files

These didn't work with the 1770 FDC, and file import
and export also weren't working

CHANGES.md

@@ -8,6 +8,9 @@ Contributors: Chris Needham, Mauro Varischetti, Bill Carr, Daniel Beardsmore
 
 * Added support for FSD format disk images. This currently only works
   with the 8271 and not the 1770 disk controller.
+* Fixed support for double-sided SSD disk images (where side 1 tracks
+  follow side 0, as opposed to DSD images, where tracks from side 0 and 1 are
+  interleaved). This only works for 80-track double-sided SSDs, not 40-track.
 * Added icons for disk and tape image file types. The installer now allows
   you to create file associations for these, and saved state files.
 * BeebEm saved state files now use the .uefstate file extension, to distinguish

Src/BeebEm.vcxproj

@@ -193,6 +193,7 @@
     <ClCompile Include="disc1770.cpp" />
     <ClCompile Include="disc8271.cpp" />
     <ClCompile Include="DiscEdit.cpp" />
+    <ClCompile Include="DiscInfo.cpp" />
     <ClCompile Include="Econet.cpp" />
     <ClCompile Include="ExportFileDialog.cpp" />
     <ClCompile Include="FileDialog.cpp" />
@@ -345,6 +346,7 @@
     <ClInclude Include="disc1770.h" />
     <ClInclude Include="disc8271.h" />
     <ClInclude Include="DiscEdit.h" />
+    <ClInclude Include="DiscInfo.h" />
     <ClInclude Include="DiscType.h" />
     <ClInclude Include="Econet.h" />
     <ClInclude Include="ExportFileDialog.h" />

Src/BeebEm.vcxproj.filters

@@ -105,6 +105,9 @@
     <ClCompile Include="DiscEdit.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="DiscInfo.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="Econet.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -353,6 +356,9 @@
     <ClInclude Include="DiscEdit.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="DiscInfo.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="DiscType.h">
       <Filter>Header Files</Filter>
     </ClInclude>

Src/DiscEdit.cpp

@@ -33,7 +33,9 @@ Boston, MA  02110-1301, USA.
 #include <string>
 
 #include "DiscEdit.h"
+#include "DiscInfo.h"
 #include "FileDialog.h"
+#include "FileUtils.h"
 
 static int DFS_LENGTH_TO_SECTORS(int Length)
 {
@@ -102,18 +104,28 @@ bool dfs_get_catalogue(const char *szDiscFile,
 
 	FILE* fd = fopen(szDiscFile, "rb");
 
-	if (fd == NULL)
+	if (fd == nullptr)
 	{
 		success = false;
 	}
 	else
 	{
+		bool DoubleSidedSSD = IsDoubleSidedSSD(szDiscFile, fd);
+
 		int catOffset = 0;
 
 		if (numSides == 2 && side == 1)
 		{
-			// Tracks are interleaved in a double sided disc image
-			catOffset = DFS_SECTORS_PER_TRACK * DFS_SECTOR_SIZE;
+			if (DoubleSidedSSD)
+			{
+				// Tracks are not interleaved, so side 2 appears after side 1
+				catOffset = 80 * DFS_SECTORS_PER_TRACK * DFS_SECTOR_SIZE;
+			}
+			else
+			{
+				// Tracks are interleaved in a double sided disc image
+				catOffset = DFS_SECTORS_PER_TRACK * DFS_SECTOR_SIZE;
+			}
 		}
 
 		if (fseek(fd, catOffset, SEEK_SET) != 0)
@@ -187,7 +199,7 @@ bool dfs_export_file(const char *szDiscFile,
 
 	FILE *discfd = fopen(szDiscFile, "rb");
 
-	if (discfd == NULL)
+	if (discfd == nullptr)
 	{
 		sprintf(szErrStr, "Failed to open disc file:\n  %s", szDiscFile);
 		return false;
@@ -202,6 +214,8 @@ bool dfs_export_file(const char *szDiscFile,
 	}
 	else
 	{
+		bool DoubleSidedSSD = IsDoubleSidedSSD(szDiscFile, discfd);
+
 		// Export the data
 		int sector = attr->startSector;
 		int len = attr->length;
@@ -217,10 +231,18 @@ bool dfs_export_file(const char *szDiscFile,
 			}
 			else
 			{
-				track = sector / DFS_SECTORS_PER_TRACK;
-				offset = (track * 2 + side) * DFS_SECTORS_PER_TRACK;
-				offset += (sector % DFS_SECTORS_PER_TRACK);
-				offset *= DFS_SECTOR_SIZE;
+				if (DoubleSidedSSD)
+				{
+					offset = 80 * DFS_SECTORS_PER_TRACK * DFS_SECTOR_SIZE;
+					offset += sector * DFS_SECTOR_SIZE;
+				}
+				else
+				{
+					track = sector / DFS_SECTORS_PER_TRACK;
+					offset = (track * 2 + side) * DFS_SECTORS_PER_TRACK;
+					offset += (sector % DFS_SECTORS_PER_TRACK);
+					offset *= DFS_SECTOR_SIZE;
+				}
 			}
 
 			// Read next sector

Src/DiscInfo.cpp

@@ -0,0 +1,43 @@
+/****************************************************************
+BeebEm - BBC Micro and Master 128 Emulator
+Copyright (C) 2009  Mike Wyatt
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public 
+License along with this program; if not, write to the Free 
+Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+Boston, MA  02110-1301, USA.
+****************************************************************/
+
+#include <stdio.h>
+
+#include "DiscInfo.h"
+#include "DiscEdit.h"
+#include "FileUtils.h"
+
+DiscInfoType DiscInfo[2];
+
+bool IsDoubleSidedSSD(const char *FileName, FILE *pFile)
+{
+	if (!HasFileExt(FileName, ".ssd"))
+	{
+		return false;
+	}
+
+	fseek(pFile, 0, SEEK_END);
+
+	long Size = ftell(pFile);
+
+	fseek(pFile, 0, SEEK_SET);
+
+	return Size > 80 * DFS_SECTORS_PER_TRACK * DFS_SECTOR_SIZE;
+}

Src/DiscInfo.h

@@ -0,0 +1,38 @@
+/****************************************************************
+BeebEm - BBC Micro and Master 128 Emulator
+Copyright (C) 2009  Mike Wyatt
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public 
+License along with this program; if not, write to the Free 
+Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+Boston, MA  02110-1301, USA.
+****************************************************************/
+
+#ifndef DISCINFO_HEADER
+#define DISCINFO_HEADER
+
+#include "DiscType.h"
+
+struct DiscInfoType
+{
+    bool Loaded; // Set to true when a disc image has been loaded
+    char FileName[256]; // Filename of disc currently in drive 0 and 1
+    DiscType Type; // Current disc type
+    bool DoubleSidedSSD; // Non-interleaved double sided disk image
+};
+
+extern DiscInfoType DiscInfo[2];
+
+bool IsDoubleSidedSSD(const char *FileName, FILE *pFile);
+
+#endif

Src/FileUtils.cpp

@@ -56,3 +56,12 @@ std::string AppendPath(const std::string& BasePath, const std::string& Path)
 
 	return PathName;
 }
+
+bool HasFileExt(const char* FileName, const char* Ext)
+{
+	const size_t ExtLen = strlen(Ext);
+	const size_t FileNameLen = strlen(FileName);
+
+	return FileNameLen >= ExtLen &&
+	       _stricmp(FileName + FileNameLen - ExtLen, Ext) == 0;
+}

Src/FileUtils.h

@@ -28,4 +28,6 @@ bool FolderExists(const char* PathName);
 
 std::string AppendPath(const std::string& BasePath, const std::string& Path);
 
+bool HasFileExt(const char* FileName, const char* Ext);
+
 #endif

Src/beebwin.cpp

@@ -56,6 +56,7 @@ using std::max;
 #include "6502core.h"
 #include "disc8271.h"
 #include "disc1770.h"
+#include "DiscInfo.h"
 #include "SysVia.h"
 #include "uservia.h"
 #include "video.h"
@@ -119,11 +120,7 @@ LEDColour DiscLedColour = LEDColour::Red;
 
 // FDC Board extension DLL variables
 HMODULE hFDCBoard;
-
 EDCB ExtBoard={0,0,NULL};
-bool DiscLoaded[2] = { false, false }; // Set to true when a disc image has been loaded
-char CDiscName[2][256]; // Filename of disc current in drive 0 and 1
-DiscType CDiscType[2]; // Current disc types
 char FDCDLL[256]={0};
 
 const char *WindowTitle = "BeebEm - BBC Model B / Master 128 Emulator";
@@ -586,11 +583,18 @@ void BeebWin::ResetBeebSystem(Model NewModelType, bool LoadRoms)
 	Reset1770();
 	AtoDInit();
 	SetRomMenu();
-	FreeDiscImage(0);
-	// Keep the disc images loaded
-	FreeDiscImage(1);
-	Close1770Disc(0);
-	Close1770Disc(1);
+
+	char szDiscName[2][MAX_PATH];
+	strcpy(szDiscName[0], DiscInfo[0].FileName);
+	strcpy(szDiscName[1], DiscInfo[1].FileName);
+
+	DiscType Type[2];
+	Type[0] = DiscInfo[0].Type;
+	Type[1] = DiscInfo[1].Type;
+
+	EjectDiscImage(0);
+	EjectDiscImage(1);
+
 	if (SCSIDriveEnabled) SCSIReset();
 	if (SCSIDriveEnabled) SASIReset();
 	if (IDEDriveEnabled)  IDEReset();
@@ -602,20 +606,54 @@ void BeebWin::ResetBeebSystem(Model NewModelType, bool LoadRoms)
 		LoadFDC(NULL, false);
 	}
 
-	if (MachineType != Model::Master128 && NativeFDC) {
+	// Keep the disc images loaded
+
+	if (MachineType != Model::Master128 && NativeFDC)
+	{
 		// 8271 disc
-		if (DiscLoaded[0] && CDiscType[0] == DiscType::SSD) LoadSimpleDiscImage(CDiscName[0], 0, 0, 80);
-		if (DiscLoaded[0] && CDiscType[0] == DiscType::DSD) LoadSimpleDSDiscImage(CDiscName[0], 0, 80);
-		if (DiscLoaded[0] && CDiscType[0] == DiscType::FSD) LoadFSDDiscImage(CDiscName[0], 0);
-		if (DiscLoaded[1] && CDiscType[1] == DiscType::SSD) LoadSimpleDiscImage(CDiscName[1], 1, 0, 80);
-		if (DiscLoaded[1] && CDiscType[1] == DiscType::DSD) LoadSimpleDSDiscImage(CDiscName[1], 1, 80);
-		if (DiscLoaded[1] && CDiscType[1] == DiscType::FSD) LoadFSDDiscImage(CDiscName[1], 1);
+		if (szDiscName[0][0] != '\0')
+		{
+			if (Type[0] == DiscType::SSD || Type[0] == DiscType::DSD)
+			{
+				Load8271DiscImage(szDiscName[0], 0, 80, Type[0]);
+			}
+			else if (Type[0] == DiscType::FSD)
+			{
+				LoadFSDDiscImage(szDiscName[0], 0);
+			}
+		}
+
+		if (szDiscName[1][0] != '\0')
+		{
+			if (Type[1] == DiscType::SSD || Type[1] == DiscType::DSD)
+			{
+				Load8271DiscImage(szDiscName[1], 1, 80, Type[1]);
+			}
+			else if (Type[1] == DiscType::FSD)
+			{
+				LoadFSDDiscImage(szDiscName[1], 1);
+			}
+		}
 	}
 
-	if ((MachineType != Model::Master128 && !NativeFDC) || (MachineType == Model::Master128)) {
+	if ((MachineType != Model::Master128 && !NativeFDC) || (MachineType == Model::Master128))
+	{
 		// 1770 Disc
-		if (DiscLoaded[0]) Load1770DiscImage(CDiscName[0], 0, CDiscType[0]);
-		if (DiscLoaded[1]) Load1770DiscImage(CDiscName[1], 1, CDiscType[1]);
+		if (szDiscName[0][0] != '\0')
+		{
+			if (Type[0] != DiscType::FSD)
+			{
+				Load1770DiscImage(szDiscName[0], 0, Type[0]);
+			}
+		}
+
+		if (szDiscName[1][0] != '\0')
+		{
+			if (Type[1] != DiscType::FSD)
+			{
+				Load1770DiscImage(szDiscName[1], 1, Type[1]);
+			}
+		}
 	}
 }
 
@@ -4723,7 +4761,7 @@ void BeebWin::HandleCommandLineFile(int Drive, const char *CmdLineFile)
 			{
 				if (NativeFDC)
 				{
-					LoadSimpleDSDiscImage(FileName, Drive, 80);
+					Load8271DiscImage(FileName, Drive, 80, DiscType::DSD);
 				}
 				else
 				{
@@ -4734,7 +4772,7 @@ void BeebWin::HandleCommandLineFile(int Drive, const char *CmdLineFile)
 			{
 				if (NativeFDC)
 				{
-					LoadSimpleDiscImage(FileName, Drive, 0, 80);
+					Load8271DiscImage(FileName, Drive, 80, DiscType::SSD);
 				}
 				else
 				{
@@ -4756,7 +4794,7 @@ void BeebWin::HandleCommandLineFile(int Drive, const char *CmdLineFile)
 			{
 				if (NativeFDC)
 				{
-					LoadSimpleDiscImage(FileName, Drive, 0, 80); // Treat like an ssd
+					Load8271DiscImage(FileName, Drive, 80, DiscType::SSD); // Treat like an ssd
 				}
 				else
 				{
@@ -4778,7 +4816,7 @@ void BeebWin::HandleCommandLineFile(int Drive, const char *CmdLineFile)
 		}
 		else // Model::Master128
 		{
-			if (Type == FileType::DSD)
+			if (Type == FileType::FSD)
 			{
 				Load1770DiscImage(FileName, Drive, DiscType::DSD);
 			}

Src/beebwin.h

@@ -338,14 +338,15 @@ class BeebWin {
 	void SetRealTimeTarget(double RealTimeTarget);
 	void TranslateKeyMapping(void);
 	bool ReadDisc(int Drive, bool bCheckForPrefs);
-	void Load1770DiscImage(const char *FileName, int Drive, DiscType Type);
+	bool Load1770DiscImage(const char *FileName, int Drive, DiscType Type);
+	bool Load8271DiscImage(const char *FileName, int Drive, int Tracks, DiscType Type);
 	void LoadTape(void);
 	void InitJoystick(void);
 	void ResetJoystick(void);
 	void RestoreState(void);
 	void SaveState(void);
 	void NewDiscImage(int Drive);
-	void CreateDiscImage(const char *FileName, int DriveNum, int Heads, int Tracks);
+	void CreateDFSDiscImage(const char *FileName, int Drive, int Heads, int Tracks);
 	void EjectDiscImage(int Drive);
 	void ExportDiscFiles(int menuId);
 	void ImportDiscFiles(int menuId);