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1 // Copyright 2014 PDFium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com | |
6 | |
7 #include "core/src/fxcodec/jbig2/JBig2_HuffmanDecoder.h" | |
8 | |
9 #include "core/src/fxcodec/jbig2/JBig2_Define.h" | |
10 | |
11 CJBig2_HuffmanDecoder::CJBig2_HuffmanDecoder(CJBig2_BitStream* pStream) | |
12 : m_pStream(pStream) { | |
13 } | |
14 | |
15 CJBig2_HuffmanDecoder::~CJBig2_HuffmanDecoder() {} | |
16 | |
17 int CJBig2_HuffmanDecoder::decodeAValue(CJBig2_HuffmanTable* pTable, | |
18 int* nResult) { | |
19 int nVal = 0; | |
20 int nBits = 0; | |
21 while (1) { | |
22 FX_DWORD nTmp; | |
23 if (m_pStream->read1Bit(&nTmp) == -1) | |
24 break; | |
25 | |
26 nVal = (nVal << 1) | nTmp; | |
27 ++nBits; | |
28 for (FX_DWORD i = 0; i < pTable->Size(); ++i) { | |
29 if (pTable->GetPREFLEN()[i] == nBits && pTable->GetCODES()[i] == nVal) { | |
30 if (pTable->IsHTOOB() && i == pTable->Size() - 1) | |
31 return JBIG2_OOB; | |
32 | |
33 if (m_pStream->readNBits(pTable->GetRANGELEN()[i], &nTmp) == -1) | |
34 return -1; | |
35 | |
36 FX_DWORD offset = pTable->IsHTOOB() ? 3 : 2; | |
37 if (i == pTable->Size() - offset) | |
38 *nResult = pTable->GetRANGELOW()[i] - nTmp; | |
39 else | |
40 *nResult = pTable->GetRANGELOW()[i] + nTmp; | |
41 return 0; | |
42 } | |
43 } | |
44 } | |
45 return -1; | |
46 } | |
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