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37
38 // for S-JIS encoding, obeserve characteristic:
39 // 1, kana character (or hankaku?) often have hight frequency of appereance
40 // 2, kana character often exist in group
41 // 3, certain combination of kana is never used in japanese language
42
43 #include "nsSJISProber.h"
44
Reset(void)45 void nsSJISProber::Reset(void)
46 {
47 mCodingSM->Reset();
48 mState = eDetecting;
49 mContextAnalyser.Reset();
50 mDistributionAnalyser.Reset();
51 }
52
HandleData(const char * aBuf,PRUint32 aLen)53 nsProbingState nsSJISProber::HandleData(const char* aBuf, PRUint32 aLen)
54 {
55 nsSMState codingState;
56
57 for (PRUint32 i = 0; i < aLen; i++)
58 {
59 codingState = mCodingSM->NextState(aBuf[i]);
60 if (codingState == eError)
61 {
62 mState = eNotMe;
63 break;
64 }
65 if (codingState == eItsMe)
66 {
67 mState = eFoundIt;
68 break;
69 }
70 if (codingState == eStart)
71 {
72 PRUint32 charLen = mCodingSM->GetCurrentCharLen();
73 if (i == 0)
74 {
75 mLastChar[1] = aBuf[0];
76 mContextAnalyser.HandleOneChar(mLastChar+2-charLen, charLen);
77 mDistributionAnalyser.HandleOneChar(mLastChar, charLen);
78 }
79 else
80 {
81 mContextAnalyser.HandleOneChar(aBuf+i+1-charLen, charLen);
82 mDistributionAnalyser.HandleOneChar(aBuf+i-1, charLen);
83 }
84 }
85 }
86
87 mLastChar[0] = aBuf[aLen-1];
88
89 if (mState == eDetecting)
90 if (mContextAnalyser.GotEnoughData() && GetConfidence() > SHORTCUT_THRESHOLD)
91 mState = eFoundIt;
92
93 return mState;
94 }
95
GetConfidence(void)96 float nsSJISProber::GetConfidence(void)
97 {
98 float contxtCf = mContextAnalyser.GetConfidence();
99 float distribCf = mDistributionAnalyser.GetConfidence();
100
101 return (contxtCf > distribCf ? contxtCf : distribCf);
102 }
103
104