/* -----------------------------------------------------------------------------
	GSFramework
	Copyright 2001-2013 Emmanuel Julien. All Rights Reserved.
----------------------------------------------------------------------------- */


		#include "filesystem/io_handle_segment.h"

		using namespace GS::IO;


//------------------------------------------------------------------------------
size_t				HandleSegment::GetSize()
{	return size;	}
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
size_t				HandleSegment::Tell()
{	return cursor;	}
size_t				HandleSegment::Seek(ptrdiff_t offset, Base::SeekRef ref)
{
	switch (ref)
	{
		case Base::SeekStart:
			cursor = offset;
			break;
		case Base::SeekCurrent:
			cursor += offset;
			break;
		case Base::SeekEnd:
			cursor = size - offset;
			break;
	}

	if	(cursor > size)
	{
		cursor = 0;
		return (size_t)-1;
	}
	return 0;
}
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/*
	IO segment must always restore the original handle position and act as
	transparently as possible.
*/
size_t				HandleSegment::Read(void *b, size_t s)
{
	size_t o = 0;

	size_t t = handle->Tell();

	if	(!handle->Seek(offset + cursor, Base::SeekStart))
	{
		if	(s > (size - cursor))
			s = size - cursor;
		o = handle->Read(b, s);
		cursor += o;
	}
	handle->Seek(t, Base::SeekStart);

	return o;
}
size_t				HandleSegment::Write(const void *b, size_t s)
{
	size_t o = 0;

	size_t t = handle->Tell();
	if	(!handle->Seek(offset + cursor, Base::SeekStart))
	{
		o = handle->Write(b, s);
		cursor += o;
	}
	handle->Seek(t, Base::SeekStart);

	return o;
}
//------------------------------------------------------------------------------