1 files changed, 109 insertions, 0 deletions

diff --git a/src/substream.cpp b/src/substream.cpp
new file mode 100644
index 0000000..ddb31b4
--- /dev/null
+++ b/src/substream.cpp
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2007-2008 Xagasoft, All rights reserved.
+ *
+ * This file is part of the libbu++ library and is released under the
+ * terms of the license contained in the file LICENSE.
+ */
+
+#include "bu/substream.h"
+
+Bu::SubStream::SubStream( Bu::Stream &rNext, long iSize ) :
+        Bu::Filter( rNext ),
+        iStart( 0 ),
+        iPos( 0 ),
+        iSize( iSize )
+{
+        iStart = rNext.tell();
+}
+
+Bu::SubStream::~SubStream()
+{
+}
+
+size_t Bu::SubStream::read( void *pBuf, size_t nBytes )
+{
+        if( (long)nBytes > iSize-iPos )
+                nBytes = iSize-iPos;
+        nBytes = rNext.read( pBuf, nBytes );
+        iPos += nBytes;
+        return nBytes;
+}
+
+size_t Bu::SubStream::write( const void *pBuf, size_t nBytes )
+{
+        if( (long)nBytes > iSize-iPos )
+                nBytes = iSize-iPos;
+        nBytes = rNext.write( pBuf, nBytes );
+        iPos += nBytes;
+        return nBytes;
+}
+
+void Bu::SubStream::start()
+{
+        // doesn't mean anything...
+}
+
+size_t Bu::SubStream::stop()
+{
+        // doesn't mean anything...
+        return 0;
+}
+
+void Bu::SubStream::close()
+{
+        // don't do anything?  maybe...
+}
+
+long Bu::SubStream::tell()
+{
+        return iPos;
+}
+
+void Bu::SubStream::seek( long offset )
+{
+        if( iPos+offset < 0 )
+                offset = -iPos;
+        else if( iPos+offset > iSize )
+                offset = iSize-iPos;
+        rNext.seek( offset );
+        iPos += offset;
+}
+
+void Bu::SubStream::setPos( long pos )
+{
+        if( pos < 0 )
+                pos = 0;
+        else if( pos > iSize )
+                pos = iSize;
+        iPos = pos;
+        pos += iStart;
+        rNext.setPos( pos );
+}
+
+void Bu::SubStream::setPosEnd( long pos )
+{
+        if( iSize-pos < 0 )
+                pos = 0;
+        else if( iSize-pos > iSize )
+                pos = iSize;
+        else
+                pos = iSize-pos;
+        iPos = pos;
+        rNext.setPos( iStart+pos );
+}
+
+bool Bu::SubStream::isEos()
+{
+        return rNext.isEos() || iPos == iSize;
+}
+
+bool Bu::SubStream::canRead()
+{
+        return rNext.canRead() && (iPos < iSize);
+}
+
+bool Bu::SubStream::canWrite()
+{
+        return rNext.canWrite() && (iPos < iSize);
+}
+