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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
**********************************************************************
* Copyright (C) 2005-2016, International Business Machines
* Corporation and others. All Rights Reserved.
**********************************************************************
*/
#include "unicode/utypes.h"
#if !UCONFIG_NO_CONVERSION
#include "cmemory.h"
#include "cstring.h"
#include "csr2022.h"
#include "csmatch.h"
U_NAMESPACE_BEGIN
/**
* Matching function shared among the 2022 detectors JP, CN and KR
* Counts up the number of legal and unrecognized escape sequences in
* the sample of text, and computes a score based on the total number &
* the proportion that fit the encoding.
*
*
* @param text the byte buffer containing text to analyse
* @param textLen the size of the text in the byte.
* @param escapeSequences the byte escape sequences to test for.
* @return match quality, in the range of 0-100.
*/
int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) const
{
int32_t i, j;
int32_t escN;
int32_t hits = 0;
int32_t misses = 0;
int32_t shifts = 0;
int32_t quality;
i = 0;
while(i < textLen) {
if(text[i] == 0x1B) {
escN = 0;
while(escN < escapeSequences_length) {
const uint8_t *seq = escapeSequences[escN];
int32_t seq_length = (int32_t)uprv_strlen((const char *) seq);
if (textLen-i >= seq_length) {
j = 1;
while(j < seq_length) {
if(seq[j] != text[i+j]) {
goto checkEscapes;
}
j += 1;
}
hits += 1;
i += seq_length-1;
goto scanInput;
}
// else we ran out of string to compare this time.
checkEscapes:
escN += 1;
}
misses += 1;
}
if( text[i]== 0x0e || text[i] == 0x0f){
shifts += 1;
}
scanInput:
i += 1;
}
if (hits == 0) {
return 0;
}
//
// Initial quality is based on relative proportion of recongized vs.
// unrecognized escape sequences.
// All good: quality = 100;
// half or less good: quality = 0;
// linear inbetween.
quality = (100*hits - 100*misses) / (hits + misses);
// Back off quality if there were too few escape sequences seen.
// Include shifts in this computation, so that KR does not get penalized
// for having only a single Escape sequence, but many shifts.
if (hits+shifts < 5) {
quality -= (5-(hits+shifts))*10;
}
if (quality < 0) {
quality = 0;
}
return quality;
}
static const uint8_t escapeSequences_2022JP[][5] = {
{0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992
{0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990
{0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978
{0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80
{0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983
{0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997
{0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII
{0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman
{0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana
{0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman
{0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1
{0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7
};
#if !UCONFIG_ONLY_HTML_CONVERSION
static const uint8_t escapeSequences_2022KR[][5] = {
{0x1b, 0x24, 0x29, 0x43, 0x00}
};
static const uint8_t escapeSequences_2022CN[][5] = {
{0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80
{0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1
{0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2
{0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165
{0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3
{0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4
{0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5
{0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6
{0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7
{0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2
{0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3
};
#endif
CharsetRecog_2022JP::~CharsetRecog_2022JP() {}
const char *CharsetRecog_2022JP::getName() const {
return "ISO-2022-JP";
}
UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const {
int32_t confidence = match_2022(textIn->fInputBytes,
textIn->fInputLen,
escapeSequences_2022JP,
UPRV_LENGTHOF(escapeSequences_2022JP));
results->set(textIn, this, confidence);
return (confidence > 0);
}
#if !UCONFIG_ONLY_HTML_CONVERSION
CharsetRecog_2022KR::~CharsetRecog_2022KR() {}
const char *CharsetRecog_2022KR::getName() const {
return "ISO-2022-KR";
}
UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const {
int32_t confidence = match_2022(textIn->fInputBytes,
textIn->fInputLen,
escapeSequences_2022KR,
UPRV_LENGTHOF(escapeSequences_2022KR));
results->set(textIn, this, confidence);
return (confidence > 0);
}
CharsetRecog_2022CN::~CharsetRecog_2022CN() {}
const char *CharsetRecog_2022CN::getName() const {
return "ISO-2022-CN";
}
UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const {
int32_t confidence = match_2022(textIn->fInputBytes,
textIn->fInputLen,
escapeSequences_2022CN,
UPRV_LENGTHOF(escapeSequences_2022CN));
results->set(textIn, this, confidence);
return (confidence > 0);
}
#endif
CharsetRecog_2022::~CharsetRecog_2022() {
// nothing to do
}
U_NAMESPACE_END
#endif
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