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88 lines
3.4 KiB
C++
88 lines
3.4 KiB
C++
// Author: Kirill Gavrilov
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// Copyright (c) 2016-2019 OPEN CASCADE SAS
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//
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// This file is part of Open CASCADE Technology software library.
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//
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// This library is free software; you can redistribute it and/or modify it under
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// the terms of the GNU Lesser General Public License version 2.1 as published
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// by the Free Software Foundation, with special exception defined in the file
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// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
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// distribution for complete text of the license and disclaimer of any warranty.
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//
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// Alternatively, this file may be used under the terms of Open CASCADE
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// commercial license or contractual agreement.
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#include <FSD_Base64Decoder.hxx>
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#include <Message.hxx>
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#include <Message_Messenger.hxx>
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// =======================================================================
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// function : Decode
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// purpose :
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// =======================================================================
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Handle(NCollection_Buffer) FSD_Base64Decoder::Decode (const Standard_Byte* theStr,
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const Standard_Size theLen)
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{
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//! Look-up table for decoding base64 stream.
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static const Standard_Byte THE_BASE64_FROM[128] =
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{
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 62, 255, 63,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 0, 255, 255, 255,
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255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 63,
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255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 255, 255, 255, 255, 255
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};
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Handle(NCollection_Buffer) aData = new NCollection_Buffer (NCollection_BaseAllocator::CommonBaseAllocator());
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if (!aData->Allocate (3 * theLen / 4))
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{
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Message::SendFail ("Fail to allocate memory.");
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return Handle(NCollection_Buffer)();
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}
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Standard_Byte* aDataPtr = aData->ChangeData();
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const Standard_Byte* anEnd = theStr + theLen;
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for (const Standard_Byte* aByteIter = theStr; aByteIter < anEnd; aByteIter += 4)
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{
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// get values for each group of four base 64 characters
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const Standard_Byte b4[4] =
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{
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aByteIter + 0 < anEnd && aByteIter[0] <= 'z' ? THE_BASE64_FROM[aByteIter[0]] : Standard_Byte(0xFF),
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aByteIter + 1 < anEnd && aByteIter[1] <= 'z' ? THE_BASE64_FROM[aByteIter[1]] : Standard_Byte(0xFF),
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aByteIter + 2 < anEnd && aByteIter[2] <= 'z' ? THE_BASE64_FROM[aByteIter[2]] : Standard_Byte(0xFF),
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aByteIter + 3 < anEnd && aByteIter[3] <= 'z' ? THE_BASE64_FROM[aByteIter[3]] : Standard_Byte(0xFF)
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};
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// transform into a group of three bytes
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const Standard_Byte b3[3] =
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{
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Standard_Byte(((b4[0] & 0x3F) << 2) + ((b4[1] & 0x30) >> 4)),
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Standard_Byte(((b4[1] & 0x0F) << 4) + ((b4[2] & 0x3C) >> 2)),
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Standard_Byte(((b4[2] & 0x03) << 6) + ((b4[3] & 0x3F) >> 0))
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};
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// add the byte to the return value if it isn't part of an '=' character (indicated by 0xFF)
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if (b4[1] != 0xFF)
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{
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*aDataPtr = b3[0];
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++aDataPtr;
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}
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if (b4[2] != 0xFF)
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{
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*aDataPtr = b3[1];
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++aDataPtr;
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}
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if (b4[3] != 0xFF)
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{
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*aDataPtr = b3[2];
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++aDataPtr;
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}
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}
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return aData;
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}
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