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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