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 #include "core/fxcrt/fx_safe_types.h" 11 CJBig2_HuffmanDecoder(CJBig2_BitStream * pStream)12CJBig2_HuffmanDecoder::CJBig2_HuffmanDecoder(CJBig2_BitStream* pStream) 13 : m_pStream(pStream) {} 14 ~CJBig2_HuffmanDecoder()15CJBig2_HuffmanDecoder::~CJBig2_HuffmanDecoder() {} 16 DecodeAValue(const CJBig2_HuffmanTable * pTable,int * nResult)17int CJBig2_HuffmanDecoder::DecodeAValue(const CJBig2_HuffmanTable* pTable, 18 int* nResult) { 19 FX_SAFE_INT32 nSafeVal = 0; 20 int nBits = 0; 21 while (1) { 22 uint32_t nTmp; 23 if (m_pStream->read1Bit(&nTmp) == -1) 24 break; 25 26 nSafeVal <<= 1; 27 if (!nSafeVal.IsValid()) 28 break; 29 30 nSafeVal |= nTmp; 31 ++nBits; 32 const int32_t nVal = nSafeVal.ValueOrDie(); 33 for (uint32_t i = 0; i < pTable->Size(); ++i) { 34 const JBig2HuffmanCode& code = pTable->GetCODES()[i]; 35 if (code.codelen != nBits || code.code != nVal) 36 continue; 37 38 if (pTable->IsHTOOB() && i == pTable->Size() - 1) 39 return JBIG2_OOB; 40 41 if (m_pStream->readNBits(pTable->GetRANGELEN()[i], &nTmp) == -1) 42 return -1; 43 44 uint32_t offset = pTable->IsHTOOB() ? 3 : 2; 45 if (i == pTable->Size() - offset) 46 *nResult = pTable->GetRANGELOW()[i] - nTmp; 47 else 48 *nResult = pTable->GetRANGELOW()[i] + nTmp; 49 return 0; 50 } 51 } 52 return -1; 53 } 54