Check in the pristine copy of ICU 4.6...

icu46/source/i18n/csrmbcs.cpp

+/*
+ **********************************************************************
+ *   Copyright (C) 2005-2008, International Business Machines
+ *   Corporation and others.  All Rights Reserved.
+ **********************************************************************
+ */
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_CONVERSION
+
+#include "csrmbcs.h"
+
+#include <math.h>
+
+U_NAMESPACE_BEGIN
+
+#define ARRAY_SIZE(array) (sizeof array / sizeof array[0])
+
+#define min(x,y) (((x)<(y))?(x):(y))
+
+static const uint16_t commonChars_sjis [] = {
+// TODO:  This set of data comes from the character frequency-
+//        of-occurence analysis tool.  The data needs to be moved
+//        into a resource and loaded from there.
+0x8140, 0x8141, 0x8142, 0x8145, 0x815b, 0x8169, 0x816a, 0x8175, 0x8176, 0x82a0,
+0x82a2, 0x82a4, 0x82a9, 0x82aa, 0x82ab, 0x82ad, 0x82af, 0x82b1, 0x82b3, 0x82b5,
+0x82b7, 0x82bd, 0x82be, 0x82c1, 0x82c4, 0x82c5, 0x82c6, 0x82c8, 0x82c9, 0x82cc,
+0x82cd, 0x82dc, 0x82e0, 0x82e7, 0x82e8, 0x82e9, 0x82ea, 0x82f0, 0x82f1, 0x8341,
+0x8343, 0x834e, 0x834f, 0x8358, 0x835e, 0x8362, 0x8367, 0x8375, 0x8376, 0x8389,
+0x838a, 0x838b, 0x838d, 0x8393, 0x8e96, 0x93fa, 0x95aa};
+
+static const uint16_t commonChars_euc_jp[] = {
+// TODO:  This set of data comes from the character frequency-
+//        of-occurence analysis tool.  The data needs to be moved
+//        into a resource and loaded from there.
+0xa1a1, 0xa1a2, 0xa1a3, 0xa1a6, 0xa1bc, 0xa1ca, 0xa1cb, 0xa1d6, 0xa1d7, 0xa4a2,
+0xa4a4, 0xa4a6, 0xa4a8, 0xa4aa, 0xa4ab, 0xa4ac, 0xa4ad, 0xa4af, 0xa4b1, 0xa4b3,
+0xa4b5, 0xa4b7, 0xa4b9, 0xa4bb, 0xa4bd, 0xa4bf, 0xa4c0, 0xa4c1, 0xa4c3, 0xa4c4,
+0xa4c6, 0xa4c7, 0xa4c8, 0xa4c9, 0xa4ca, 0xa4cb, 0xa4ce, 0xa4cf, 0xa4d0, 0xa4de,
+0xa4df, 0xa4e1, 0xa4e2, 0xa4e4, 0xa4e8, 0xa4e9, 0xa4ea, 0xa4eb, 0xa4ec, 0xa4ef,
+0xa4f2, 0xa4f3, 0xa5a2, 0xa5a3, 0xa5a4, 0xa5a6, 0xa5a7, 0xa5aa, 0xa5ad, 0xa5af,
+0xa5b0, 0xa5b3, 0xa5b5, 0xa5b7, 0xa5b8, 0xa5b9, 0xa5bf, 0xa5c3, 0xa5c6, 0xa5c7,
+0xa5c8, 0xa5c9, 0xa5cb, 0xa5d0, 0xa5d5, 0xa5d6, 0xa5d7, 0xa5de, 0xa5e0, 0xa5e1,
+0xa5e5, 0xa5e9, 0xa5ea, 0xa5eb, 0xa5ec, 0xa5ed, 0xa5f3, 0xb8a9, 0xb9d4, 0xbaee,
+0xbbc8, 0xbef0, 0xbfb7, 0xc4ea, 0xc6fc, 0xc7bd, 0xcab8, 0xcaf3, 0xcbdc, 0xcdd1};
+
+static const uint16_t commonChars_euc_kr[] = {
+// TODO:  This set of data comes from the character frequency-
+//        of-occurence analysis tool.  The data needs to be moved
+//        into a resource and loaded from there.
+0xb0a1, 0xb0b3, 0xb0c5, 0xb0cd, 0xb0d4, 0xb0e6, 0xb0ed, 0xb0f8, 0xb0fa, 0xb0fc,
+0xb1b8, 0xb1b9, 0xb1c7, 0xb1d7, 0xb1e2, 0xb3aa, 0xb3bb, 0xb4c2, 0xb4cf, 0xb4d9,
+0xb4eb, 0xb5a5, 0xb5b5, 0xb5bf, 0xb5c7, 0xb5e9, 0xb6f3, 0xb7af, 0xb7c2, 0xb7ce,
+0xb8a6, 0xb8ae, 0xb8b6, 0xb8b8, 0xb8bb, 0xb8e9, 0xb9ab, 0xb9ae, 0xb9cc, 0xb9ce,
+0xb9fd, 0xbab8, 0xbace, 0xbad0, 0xbaf1, 0xbbe7, 0xbbf3, 0xbbfd, 0xbcad, 0xbcba,
+0xbcd2, 0xbcf6, 0xbdba, 0xbdc0, 0xbdc3, 0xbdc5, 0xbec6, 0xbec8, 0xbedf, 0xbeee,
+0xbef8, 0xbefa, 0xbfa1, 0xbfa9, 0xbfc0, 0xbfe4, 0xbfeb, 0xbfec, 0xbff8, 0xc0a7,
+0xc0af, 0xc0b8, 0xc0ba, 0xc0bb, 0xc0bd, 0xc0c7, 0xc0cc, 0xc0ce, 0xc0cf, 0xc0d6,
+0xc0da, 0xc0e5, 0xc0fb, 0xc0fc, 0xc1a4, 0xc1a6, 0xc1b6, 0xc1d6, 0xc1df, 0xc1f6,
+0xc1f8, 0xc4a1, 0xc5cd, 0xc6ae, 0xc7cf, 0xc7d1, 0xc7d2, 0xc7d8, 0xc7e5, 0xc8ad};
+
+static const uint16_t commonChars_big5[] = {
+// TODO:  This set of data comes from the character frequency-
+//        of-occurence analysis tool.  The data needs to be moved
+//        into a resource and loaded from there.
+0xa140, 0xa141, 0xa142, 0xa143, 0xa147, 0xa149, 0xa175, 0xa176, 0xa440, 0xa446,
+0xa447, 0xa448, 0xa451, 0xa454, 0xa457, 0xa464, 0xa46a, 0xa46c, 0xa477, 0xa4a3,
+0xa4a4, 0xa4a7, 0xa4c1, 0xa4ce, 0xa4d1, 0xa4df, 0xa4e8, 0xa4fd, 0xa540, 0xa548,
+0xa558, 0xa569, 0xa5cd, 0xa5e7, 0xa657, 0xa661, 0xa662, 0xa668, 0xa670, 0xa6a8,
+0xa6b3, 0xa6b9, 0xa6d3, 0xa6db, 0xa6e6, 0xa6f2, 0xa740, 0xa751, 0xa759, 0xa7da,
+0xa8a3, 0xa8a5, 0xa8ad, 0xa8d1, 0xa8d3, 0xa8e4, 0xa8fc, 0xa9c0, 0xa9d2, 0xa9f3,
+0xaa6b, 0xaaba, 0xaabe, 0xaacc, 0xaafc, 0xac47, 0xac4f, 0xacb0, 0xacd2, 0xad59,
+0xaec9, 0xafe0, 0xb0ea, 0xb16f, 0xb2b3, 0xb2c4, 0xb36f, 0xb44c, 0xb44e, 0xb54c,
+0xb5a5, 0xb5bd, 0xb5d0, 0xb5d8, 0xb671, 0xb7ed, 0xb867, 0xb944, 0xbad8, 0xbb44,
+0xbba1, 0xbdd1, 0xc2c4, 0xc3b9, 0xc440, 0xc45f};
+
+static const uint16_t commonChars_gb_18030[] = {
+// TODO:  This set of data comes from the character frequency-
+//        of-occurence analysis tool.  The data needs to be moved
+//        into a resource and loaded from there.
+0xa1a1, 0xa1a2, 0xa1a3, 0xa1a4, 0xa1b0, 0xa1b1, 0xa1f1, 0xa1f3, 0xa3a1, 0xa3ac,
+0xa3ba, 0xb1a8, 0xb1b8, 0xb1be, 0xb2bb, 0xb3c9, 0xb3f6, 0xb4f3, 0xb5bd, 0xb5c4,
+0xb5e3, 0xb6af, 0xb6d4, 0xb6e0, 0xb7a2, 0xb7a8, 0xb7bd, 0xb7d6, 0xb7dd, 0xb8b4,
+0xb8df, 0xb8f6, 0xb9ab, 0xb9c9, 0xb9d8, 0xb9fa, 0xb9fd, 0xbacd, 0xbba7, 0xbbd6,
+0xbbe1, 0xbbfa, 0xbcbc, 0xbcdb, 0xbcfe, 0xbdcc, 0xbecd, 0xbedd, 0xbfb4, 0xbfc6,
+0xbfc9, 0xc0b4, 0xc0ed, 0xc1cb, 0xc2db, 0xc3c7, 0xc4dc, 0xc4ea, 0xc5cc, 0xc6f7,
+0xc7f8, 0xc8ab, 0xc8cb, 0xc8d5, 0xc8e7, 0xc9cf, 0xc9fa, 0xcab1, 0xcab5, 0xcac7,
+0xcad0, 0xcad6, 0xcaf5, 0xcafd, 0xccec, 0xcdf8, 0xceaa, 0xcec4, 0xced2, 0xcee5,
+0xcfb5, 0xcfc2, 0xcfd6, 0xd0c2, 0xd0c5, 0xd0d0, 0xd0d4, 0xd1a7, 0xd2aa, 0xd2b2,
+0xd2b5, 0xd2bb, 0xd2d4, 0xd3c3, 0xd3d0, 0xd3fd, 0xd4c2, 0xd4da, 0xd5e2, 0xd6d0};
+
+static int32_t binarySearch(const uint16_t *array, int32_t len, uint16_t value)
+{
+    int32_t start = 0, end = len-1;
+    int32_t mid = (start+end)/2;
+
+    while(start <= end) {
+        if(array[mid] == value) {
+            return mid;
+        }
+
+        if(array[mid] < value){
+            start = mid+1;
+        } else {
+            end = mid-1;
+        }
+
+        mid = (start+end)/2;
+    }
+
+    return -1;
+}
+
+IteratedChar::IteratedChar() : 
+charValue(0), index(-1), nextIndex(0), error(FALSE), done(FALSE)
+{
+    // nothing else to do.
+}
+
+/*void IteratedChar::reset()
+{
+    charValue = 0;
+    index     = -1;
+    nextIndex = 0;
+    error     = FALSE;
+    done      = FALSE;
+}*/
+
+int32_t IteratedChar::nextByte(InputText *det)
+{
+    if (nextIndex >= det->fRawLength) {
+        done = TRUE;
+
+        return -1;
+    }
+
+    return det->fRawInput[nextIndex++];
+}
+
+CharsetRecog_mbcs::~CharsetRecog_mbcs()
+{
+    // nothing to do.
+}
+
+int32_t CharsetRecog_mbcs::match_mbcs(InputText *det, const uint16_t commonChars[], int32_t commonCharsLen) {
+    int32_t singleByteCharCount = 0;
+    int32_t doubleByteCharCount = 0;
+    int32_t commonCharCount     = 0;
+    int32_t badCharCount        = 0;
+    int32_t totalCharCount      = 0;
+    int32_t confidence          = 0;
+    IteratedChar iter;
+
+    while (nextChar(&iter, det)) {
+        totalCharCount++;
+
+        if (iter.error) {
+            badCharCount++;
+        } else {
+            if (iter.charValue <= 0xFF) {
+                singleByteCharCount++;
+            } else {
+                doubleByteCharCount++;
+
+                if (commonChars != 0) {
+                    if (binarySearch(commonChars, commonCharsLen, iter.charValue) >= 0){
+                        commonCharCount += 1;
+                    }
+                }
+            }
+        }
+
+
+        if (badCharCount >= 2 && badCharCount*5 >= doubleByteCharCount) {
+            // Bail out early if the byte data is not matching the encoding scheme.
+            // break detectBlock;
+            return confidence;
+        }
+    }
+
+    if (doubleByteCharCount <= 10 && badCharCount == 0) {
+        // Not many multi-byte chars.
+        if (doubleByteCharCount == 0 && totalCharCount < 10) {
+            // There weren't any multibyte sequences, and there was a low density of non-ASCII single bytes.
+            // We don't have enough data to have any confidence.
+            // Statistical analysis of single byte non-ASCII charcters would probably help here.
+            confidence = 0;
+        }
+        else {
+            //   ASCII or ISO file?  It's probably not our encoding,
+            //   but is not incompatible with our encoding, so don't give it a zero.
+            confidence = 10;
+        }
+
+        return confidence;
+    }
+
+    //
+    //  No match if there are too many characters that don't fit the encoding scheme.
+    //    (should we have zero tolerance for these?)
+    //
+    if (doubleByteCharCount < 20*badCharCount) {
+        confidence = 0;
+
+        return confidence;
+    }
+
+    if (commonChars == 0) {
+        // We have no statistics on frequently occuring characters.
+        //  Assess confidence purely on having a reasonable number of
+        //  multi-byte characters (the more the better)
+        confidence = 30 + doubleByteCharCount - 20*badCharCount;
+
+        if (confidence > 100) {
+            confidence = 100;
+        }
+    } else {
+        //
+        // Frequency of occurence statistics exist.
+        //
+
+        double maxVal = log10((double)doubleByteCharCount / 4); /*(float)?*/
+        double scaleFactor = 90.0 / maxVal;
+        confidence = (int32_t)(log10((double)commonCharCount+1) * scaleFactor + 10.0);
+
+        confidence = min(confidence, 100);
+    }
+
+    if (confidence < 0) {
+        confidence = 0;
+    }
+
+    return confidence;
+}
+
+CharsetRecog_sjis::~CharsetRecog_sjis()
+{
+    // nothing to do
+}
+
+UBool CharsetRecog_sjis::nextChar(IteratedChar* it, InputText* det) {
+    it->index = it->nextIndex;
+    it->error = FALSE;
+
+    int32_t firstByte = it->charValue = it->nextByte(det);
+
+    if (firstByte < 0) {
+        return FALSE;
+    }
+
+    if (firstByte <= 0x7F || (firstByte > 0xA0 && firstByte <= 0xDF)) {
+        return TRUE;
+    }
+
+    int32_t secondByte = it->nextByte(det);
+    if (secondByte >= 0) {
+        it->charValue = (firstByte << 8) | secondByte;
+    }
+    // else we'll handle the error later.
+
+    if (! ((secondByte >= 0x40 && secondByte <= 0x7F) || (secondByte >= 0x80 && secondByte <= 0xFE))) {
+        // Illegal second byte value.
+        it->error = TRUE;
+    }
+
+    return TRUE;
+}
+
+int32_t CharsetRecog_sjis::match(InputText* det)
+{
+    return match_mbcs(det, commonChars_sjis, ARRAY_SIZE(commonChars_sjis));
+}
+
+const char *CharsetRecog_sjis::getName() const
+{
+    return "Shift_JIS";
+}
+
+const char *CharsetRecog_sjis::getLanguage() const
+{
+    return "ja";
+}
+
+CharsetRecog_euc::~CharsetRecog_euc()
+{
+    // nothing to do
+}
+
+UBool CharsetRecog_euc::nextChar(IteratedChar* it, InputText* det) {
+    int32_t firstByte  = 0;
+    int32_t secondByte = 0;
+    int32_t thirdByte  = 0;
+
+    it->index = it->nextIndex;
+    it->error = FALSE;
+    firstByte = it->charValue = it->nextByte(det);
+
+    if (firstByte < 0) {
+        // Ran off the end of the input data
+        return FALSE;
+    }
+
+    if (firstByte <= 0x8D) {
+        // single byte char
+        return TRUE;
+    }
+
+    secondByte = it->nextByte(det);
+    if (secondByte >= 0) {
+        it->charValue = (it->charValue << 8) | secondByte;
+    }
+    // else we'll handle the error later.
+
+    if (firstByte >= 0xA1 && firstByte <= 0xFE) {
+        // Two byte Char
+        if (secondByte < 0xA1) {
+            it->error = TRUE;
+        }
+
+        return TRUE;
+    }
+
+    if (firstByte == 0x8E) {
+        // Code Set 2.
+        //   In EUC-JP, total char size is 2 bytes, only one byte of actual char value.
+        //   In EUC-TW, total char size is 4 bytes, three bytes contribute to char value.
+        // We don't know which we've got.
+        // Treat it like EUC-JP.  If the data really was EUC-TW, the following two
+        //   bytes will look like a well formed 2 byte char.
+        if (secondByte < 0xA1) {
+            it->error = TRUE;
+        }
+
+        return TRUE;
+    }
+
+    if (firstByte == 0x8F) {
+        // Code set 3.
+        // Three byte total char size, two bytes of actual char value.
+        thirdByte    = it->nextByte(det);
+        it->charValue = (it->charValue << 8) | thirdByte;
+
+        if (thirdByte < 0xa1) {
+            // Bad second byte or ran off the end of the input data with a non-ASCII first byte.
+            it->error = TRUE;
+        }
+    }
+
+    return TRUE;
+
+}
+
+CharsetRecog_euc_jp::~CharsetRecog_euc_jp()
+{
+    // nothing to do
+}
+
+const char *CharsetRecog_euc_jp::getName() const
+{
+    return "EUC-JP";
+}
+
+const char *CharsetRecog_euc_jp::getLanguage() const
+{
+    return "ja";
+}
+
+int32_t CharsetRecog_euc_jp::match(InputText *det)
+{
+    return match_mbcs(det, commonChars_euc_jp, ARRAY_SIZE(commonChars_euc_jp));
+}
+
+CharsetRecog_euc_kr::~CharsetRecog_euc_kr()
+{
+    // nothing to do
+}
+
+const char *CharsetRecog_euc_kr::getName() const
+{
+    return "EUC-KR";
+}
+
+const char *CharsetRecog_euc_kr::getLanguage() const
+{
+    return "ko";
+}
+
+int32_t CharsetRecog_euc_kr::match(InputText *det)
+{
+    return match_mbcs(det, commonChars_euc_kr, ARRAY_SIZE(commonChars_euc_kr));
+}
+
+CharsetRecog_big5::~CharsetRecog_big5()
+{
+    // nothing to do
+}
+
+UBool CharsetRecog_big5::nextChar(IteratedChar* it, InputText* det)
+{
+    int32_t firstByte;
+
+    it->index = it->nextIndex;
+    it->error = FALSE;
+    firstByte = it->charValue = it->nextByte(det);
+
+    if (firstByte < 0) {
+        return FALSE;
+    }
+
+    if (firstByte <= 0x7F || firstByte == 0xFF) {
+        // single byte character.
+        return TRUE;
+    }
+
+    int32_t secondByte = it->nextByte(det);
+    if (secondByte >= 0)  {
+        it->charValue = (it->charValue << 8) | secondByte;
+    }
+    // else we'll handle the error later.
+
+    if (secondByte < 0x40 || secondByte == 0x7F || secondByte == 0xFF) {
+        it->error = TRUE;
+    }
+
+    return TRUE;
+}
+
+const char *CharsetRecog_big5::getName() const
+{
+    return "Big5";
+}
+
+const char *CharsetRecog_big5::getLanguage() const
+{
+    return "zh";
+}
+
+int32_t CharsetRecog_big5::match(InputText *det)
+{
+    return match_mbcs(det, commonChars_big5, ARRAY_SIZE(commonChars_big5));
+}
+
+CharsetRecog_gb_18030::~CharsetRecog_gb_18030()
+{
+    // nothing to do
+}
+
+UBool CharsetRecog_gb_18030::nextChar(IteratedChar* it, InputText* det) {
+    int32_t firstByte  = 0;
+    int32_t secondByte = 0;
+    int32_t thirdByte  = 0;
+    int32_t fourthByte = 0;
+
+    it->index = it->nextIndex;
+    it->error = FALSE;
+    firstByte = it->charValue = it->nextByte(det);
+
+    if (firstByte < 0) {
+        // Ran off the end of the input data
+        return FALSE;
+    }
+
+    if (firstByte <= 0x80) {
+        // single byte char
+        return TRUE;
+    }
+
+    secondByte = it->nextByte(det);
+    if (secondByte >= 0) {
+        it->charValue = (it->charValue << 8) | secondByte;
+    }
+    // else we'll handle the error later.
+
+    if (firstByte >= 0x81 && firstByte <= 0xFE) {
+        // Two byte Char
+        if ((secondByte >= 0x40 && secondByte <= 0x7E) || (secondByte >=80 && secondByte <= 0xFE)) {
+            return TRUE;
+        }
+
+        // Four byte char
+        if (secondByte >= 0x30 && secondByte <= 0x39) {
+            thirdByte = it->nextByte(det);
+
+            if (thirdByte >= 0x81 && thirdByte <= 0xFE) {
+                fourthByte = it->nextByte(det);
+
+                if (fourthByte >= 0x30 && fourthByte <= 0x39) {
+                    it->charValue = (it->charValue << 16) | (thirdByte << 8) | fourthByte;
+
+                    return TRUE;
+                }
+            }
+        }
+
+        // Something wasn't valid, or we ran out of data (-1).
+        it->error = TRUE;
+    }
+
+    return TRUE;
+}
+
+const char *CharsetRecog_gb_18030::getName() const
+{
+    return "GB18030";
+}
+
+const char *CharsetRecog_gb_18030::getLanguage() const
+{
+    return "zh";
+}
+
+int32_t CharsetRecog_gb_18030::match(InputText *det)
+{
+    return match_mbcs(det, commonChars_gb_18030, ARRAY_SIZE(commonChars_gb_18030));
+}
+
+U_NAMESPACE_END
+#endif