118 lines
2.1 KiB
C++
118 lines
2.1 KiB
C++
// Copyright (C) 2002-2008 Nikolaus Gebhardt
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// This file is part of the "Irrlicht Engine".
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// For conditions of distribution and use, see copyright notice in irrlicht.h
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#include "CLimitReadFile.h"
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#include "irrString.h"
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namespace irr
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{
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namespace io
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{
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CLimitReadFile::CLimitReadFile(IReadFile* alreadyOpenedFile, long areaSize, const c8* name)
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: Filename(name), AreaSize(areaSize), AreaStart(0), AreaEnd(0), File(alreadyOpenedFile)
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{
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#ifdef _DEBUG
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setDebugName("CLimitReadFile");
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#endif
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if (File)
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File->grab();
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init();
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}
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void CLimitReadFile::init()
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{
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if (!File)
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return;
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AreaStart = File->getPos();
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AreaEnd = AreaStart + AreaSize;
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}
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CLimitReadFile::~CLimitReadFile()
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{
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if (File)
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File->drop();
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}
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//! returns how much was read
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s32 CLimitReadFile::read(void* buffer, u32 sizeToRead)
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{
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const long pos = File->getPos();
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if (pos >= AreaEnd)
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return 0;
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if (pos + (long)sizeToRead >= AreaEnd)
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sizeToRead = AreaEnd - pos;
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return File->read(buffer, sizeToRead);
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}
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//! changes position in file, returns true if successful
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//! if relativeMovement==true, the pos is changed relative to current pos,
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//! otherwise from begin of file
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bool CLimitReadFile::seek(long finalPos, bool relativeMovement)
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{
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const long pos = File->getPos();
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if (relativeMovement)
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{
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if (pos + finalPos > AreaEnd)
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finalPos = AreaEnd - pos;
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}
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else
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{
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finalPos += AreaStart;
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if (finalPos > AreaEnd)
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return false;
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}
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return File->seek(finalPos, relativeMovement);
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}
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//! returns size of file
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long CLimitReadFile::getSize() const
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{
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return AreaSize;
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}
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//! returns where in the file we are.
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long CLimitReadFile::getPos() const
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{
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return File->getPos() - AreaStart;
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}
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//! returns name of file
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const c8* CLimitReadFile::getFileName() const
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{
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return Filename.c_str();
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}
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IReadFile* createLimitReadFile(const c8* fileName, IReadFile* alreadyOpenedFile, long areaSize)
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{
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return new CLimitReadFile(alreadyOpenedFile, areaSize, fileName);
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}
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} // end namespace io
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} // end namespace irr
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