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/fxcodec/jbig2/JBig2_HuffmanDecoder.h"
8 
9 #include "core/fxcodec/jbig2/JBig2_Define.h"
10 
CJBig2_HuffmanDecoder(CJBig2_BitStream * pStream)11 CJBig2_HuffmanDecoder::CJBig2_HuffmanDecoder(CJBig2_BitStream* pStream)
12     : m_pStream(pStream) {}
13 
~CJBig2_HuffmanDecoder()14 CJBig2_HuffmanDecoder::~CJBig2_HuffmanDecoder() {}
15 
decodeAValue(CJBig2_HuffmanTable * pTable,int * nResult)16 int CJBig2_HuffmanDecoder::decodeAValue(CJBig2_HuffmanTable* pTable,
17                                         int* nResult) {
18   int nVal = 0;
19   int nBits = 0;
20   while (1) {
21     uint32_t nTmp;
22     if (m_pStream->read1Bit(&nTmp) == -1)
23       break;
24 
25     nVal = (nVal << 1) | nTmp;
26     ++nBits;
27     for (uint32_t i = 0; i < pTable->Size(); ++i) {
28       if (pTable->GetPREFLEN()[i] == nBits && pTable->GetCODES()[i] == nVal) {
29         if (pTable->IsHTOOB() && i == pTable->Size() - 1)
30           return JBIG2_OOB;
31 
32         if (m_pStream->readNBits(pTable->GetRANGELEN()[i], &nTmp) == -1)
33           return -1;
34 
35         uint32_t offset = pTable->IsHTOOB() ? 3 : 2;
36         if (i == pTable->Size() - offset)
37           *nResult = pTable->GetRANGELOW()[i] - nTmp;
38         else
39           *nResult = pTable->GetRANGELOW()[i] + nTmp;
40         return 0;
41       }
42     }
43   }
44   return -1;
45 }
46