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0001 /* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
0002 /* ***** BEGIN LICENSE BLOCK *****
0003  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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0023  *
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0036  * ***** END LICENSE BLOCK ***** */
0037 
0038 // for japanese encoding, observe characteristic:
0039 // 1, kana character (or hankaku?) often have hight frequency of appearance
0040 // 2, kana character often exist in group
0041 // 3, certain combination of kana is never used in japanese language
0042 
0043 #pragma GCC visibility push(hidden)
0044 
0045 #include "nsEUCJPProber.h"
0046 
0047 void  nsEUCJPProber::Reset(void)
0048 {
0049   mCodingSM->Reset(); 
0050   mState = eDetecting;
0051   mContextAnalyser.Reset();
0052   mDistributionAnalyser.Reset();
0053 }
0054 
0055 nsProbingState nsEUCJPProber::HandleData(const char* aBuf, PRUint32 aLen)
0056 {
0057   nsSMState codingState;
0058 
0059   for (PRUint32 i = 0; i < aLen; i++)
0060   {
0061     codingState = mCodingSM->NextState(aBuf[i]);
0062     if (codingState == eError)
0063     {
0064       mState = eNotMe;
0065       break;
0066     }
0067     if (codingState == eItsMe)
0068     {
0069       mState = eFoundIt;
0070       break;
0071     }
0072     if (codingState == eStart)
0073     {
0074       PRUint32 charLen = mCodingSM->GetCurrentCharLen();
0075 
0076       if (i == 0)
0077       {
0078         mLastChar[1] = aBuf[0];
0079         mContextAnalyser.HandleOneChar(mLastChar, charLen);
0080         mDistributionAnalyser.HandleOneChar(mLastChar, charLen);
0081       }
0082       else
0083       {
0084         mContextAnalyser.HandleOneChar(aBuf+i-1, charLen);
0085         mDistributionAnalyser.HandleOneChar(aBuf+i-1, charLen);
0086       }
0087     }
0088   }
0089 
0090   mLastChar[0] = aBuf[aLen-1];
0091 
0092   if (mState == eDetecting)
0093     if (mContextAnalyser.GotEnoughData() && GetConfidence() > SHORTCUT_THRESHOLD)
0094       mState = eFoundIt;
0095 
0096   return mState;
0097 }
0098 
0099 float nsEUCJPProber::GetConfidence(void)
0100 {
0101   float contxtCf = mContextAnalyser.GetConfidence();
0102   float distribCf = mDistributionAnalyser.GetConfidence();
0103 
0104   return (contxtCf > distribCf ? contxtCf : distribCf);
0105 }
0106 
0107 #pragma GCC visibility pop
0108