moved ConstrainedDataStream into its own file

moved the ConstrainedDataStream into its own source file and changed
BSAFile to use it though the exposed factory function. This is in
preperation foreimplementing it based on feedback from profiling that
(at least on windows) the C++ iostreams library is quite slow.

components/CMakeLists.txt

@@ -48,7 +48,7 @@ add_component_dir (misc
 
 add_component_dir (files
     linuxpath windowspath macospath fixedpath multidircollection collections fileops configurationmanager
-    filelibrary ogreplugin
+    filelibrary ogreplugin constrainedfiledatastream
     )
 
 add_component_dir (compiler

components/bsa/bsa_file.cpp

@@ -23,94 +23,15 @@
 
 #include "bsa_file.hpp"
 
-#include <stdexcept>
+//#include <stdexcept>
-#include <cstdlib>
+//#include <cstdlib>
-#include <cassert>
+//#include <cassert>
 
-#include <OgreDataStream.h>
+#include "../files/constrainedfiledatastream.hpp"
 
 using namespace std;
 using namespace Bsa;
 
-class ConstrainedDataStream : public Ogre::DataStream {
-    std::ifstream mStream;
-    const size_t mStart;
-    size_t mPos;
-    bool mIsEOF;
-
-public:
-    ConstrainedDataStream(const Ogre::String &fname, size_t start, size_t length)
-      : mStream(fname.c_str(), std::ios_base::binary), mStart(start), mPos(0), mIsEOF(false)
-    {
-        mSize = length;
-        if(!mStream.seekg(mStart, std::ios_base::beg))
-            throw std::runtime_error("Error seeking to start of BSA entry");
-    }
-
-    ConstrainedDataStream(const Ogre::String &name, const Ogre::String &fname,
-                          size_t start, size_t length)
-      : Ogre::DataStream(name), mStream(fname.c_str(), std::ios_base::binary),
-        mStart(start), mPos(0), mIsEOF(false)
-    {
-        mSize = length;
-        if(!mStream.seekg(mStart, std::ios_base::beg))
-            throw std::runtime_error("Error seeking to start of BSA entry");
-    }
-
-
-    virtual size_t read(void *buf, size_t count)
-    {
-        mStream.clear();
-
-        if(count > mSize-mPos)
-        {
-            count = mSize-mPos;
-            mIsEOF = true;
-        }
-        mStream.read(reinterpret_cast<char*>(buf), count);
-
-        count = mStream.gcount();
-        mPos += count;
-        return count;
-    }
-
-    virtual void skip(long count)
-    {
-        if((count >= 0 && (size_t)count <= mSize-mPos) ||
-           (count < 0 && (size_t)-count <= mPos))
-        {
-            mStream.clear();
-            if(mStream.seekg(count, std::ios_base::cur))
-            {
-                mPos += count;
-                mIsEOF = false;
-            }
-        }
-    }
-
-    virtual void seek(size_t pos)
-    {
-        if(pos < mSize)
-        {
-            mStream.clear();
-            if(mStream.seekg(pos+mStart, std::ios_base::beg))
-            {
-                mPos = pos;
-                mIsEOF = false;
-            }
-        }
-    }
-
-    virtual size_t tell() const
-    { return mPos; }
-
-    virtual bool eof() const
-    { return mIsEOF; }
-
-    virtual void close()
-    { mStream.close(); }
-};
-
 
 /// Error handling
 void BSAFile::fail(const string &msg)
@@ -253,5 +174,5 @@ Ogre::DataStreamPtr BSAFile::getFile(const char *file)
         fail("File not found: " + string(file));
 
     const FileStruct &fs = files[i];
-    return Ogre::DataStreamPtr(new ConstrainedDataStream(filename, fs.offset, fs.fileSize));
+	return openConstrainedFileDataStream (filename.c_str (), fs.offset, fs.fileSize);
 }

components/files/constrainedfiledatastream.cpp

@@ -0,0 +1,112 @@
+/*
+  OpenMW - The completely unofficial reimplementation of Morrowind
+  Copyright (C) 2008-2010  Nicolay Korslund
+  Email: < korslund@gmail.com >
+  WWW: http://openmw.sourceforge.net/
+
+  This file (bsa_file.cpp) is part of the OpenMW package.
+
+  OpenMW is distributed as free software: you can redistribute it
+  and/or modify it under the terms of the GNU General Public License
+  version 3, as published by the Free Software Foundation.
+
+  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
+  version 3 along with this program. If not, see
+  http://www.gnu.org/licenses/ .
+
+ */
+
+#include "constrainedfiledatastream.hpp"
+
+#include <stdexcept>
+
+class ConstrainedDataStream : public Ogre::DataStream {
+    std::ifstream mStream;
+    const size_t mStart;
+    size_t mPos;
+    bool mIsEOF;
+
+public:
+    ConstrainedDataStream(const Ogre::String &fname, size_t start, size_t length)
+      : mStream(fname.c_str(), std::ios_base::binary), mStart(start), mPos(0), mIsEOF(false)
+    {
+        mSize = length;
+        if(!mStream.seekg(mStart, std::ios_base::beg))
+            throw std::runtime_error("Error seeking to start of BSA entry");
+    }
+
+    ConstrainedDataStream(const Ogre::String &name, const Ogre::String &fname,
+                          size_t start, size_t length)
+      : Ogre::DataStream(name), mStream(fname.c_str(), std::ios_base::binary),
+        mStart(start), mPos(0), mIsEOF(false)
+    {
+        mSize = length;
+        if(!mStream.seekg(mStart, std::ios_base::beg))
+            throw std::runtime_error("Error seeking to start of BSA entry");
+    }
+
+
+    virtual size_t read(void *buf, size_t count)
+    {
+        mStream.clear();
+
+        if(count > mSize-mPos)
+        {
+            count = mSize-mPos;
+            mIsEOF = true;
+        }
+        mStream.read(reinterpret_cast<char*>(buf), count);
+
+        count = mStream.gcount();
+        mPos += count;
+        return count;
+    }
+
+    virtual void skip(long count)
+    {
+        if((count >= 0 && (size_t)count <= mSize-mPos) ||
+           (count < 0 && (size_t)-count <= mPos))
+        {
+            mStream.clear();
+            if(mStream.seekg(count, std::ios_base::cur))
+            {
+                mPos += count;
+                mIsEOF = false;
+            }
+        }
+    }
+
+    virtual void seek(size_t pos)
+    {
+        if(pos < mSize)
+        {
+            mStream.clear();
+            if(mStream.seekg(pos+mStart, std::ios_base::beg))
+            {
+                mPos = pos;
+                mIsEOF = false;
+            }
+        }
+    }
+
+    virtual size_t tell() const
+    { return mPos; }
+
+    virtual bool eof() const
+    { return mIsEOF; }
+
+    virtual void close()
+    { mStream.close(); }
+};
+
+Ogre::DataStreamPtr openConstrainedFileDataStream (char const * filename, size_t offset, size_t length)
+{
+	assert (length != 0xFFFFFFFF); // reserved for future use...
+
+	return Ogre::DataStreamPtr(new ConstrainedDataStream(filename, offset, length));
+}

components/files/constrainedfiledatastream.hpp

@@ -0,0 +1,8 @@
+#ifndef COMPONENTS_FILES_CONSTRAINEDFILEDATASTREAM_HPP
+#define COMPONENTS_FILES_CONSTRAINEDFILEDATASTREAM_HPP
+
+#include <OgreDataStream.h>
+
+Ogre::DataStreamPtr openConstrainedFileDataStream (char const * filename, size_t offset = 0, size_t length = 0xFFFFFFFF);
+
+#endif // COMPONENTS_FILES_CONSTRAINEDFILEDATASTREAM_HPP