// Copyright (C) 2016 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html /* ********************************************************************** * Copyright (C) 2005-2013, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** */ #include "unicode/utypes.h" #if !UCONFIG_NO_CONVERSION #include "csrucode.h" #include "csmatch.h" U_NAMESPACE_BEGIN CharsetRecog_Unicode::~CharsetRecog_Unicode() { // nothing to do } CharsetRecog_UTF_16_BE::~CharsetRecog_UTF_16_BE() { // nothing to do } const char *CharsetRecog_UTF_16_BE::getName() const { return "UTF-16BE"; } // UTF-16 confidence calculation. Very simple minded, but better than nothing. // Any 8 bit non-control characters bump the confidence up. These have a zero high byte, // and are very likely to be UTF-16, although they could also be part of a UTF-32 code. // NULs are a contra-indication, they will appear commonly if the actual encoding is UTF-32. // NULs should be rare in actual text. static int32_t adjustConfidence(UChar codeUnit, int32_t confidence) { if (codeUnit == 0) { confidence -= 10; } else if ((codeUnit >= 0x20 && codeUnit <= 0xff) || codeUnit == 0x0a) { confidence += 10; } if (confidence < 0) { confidence = 0; } else if (confidence > 100) { confidence = 100; } return confidence; } UBool CharsetRecog_UTF_16_BE::match(InputText* textIn, CharsetMatch *results) const { const uint8_t *input = textIn->fRawInput; int32_t confidence = 10; int32_t length = textIn->fRawLength; int32_t bytesToCheck = (length > 30) ? 30 : length; for (int32_t charIndex=0; charIndex<bytesToCheck-1; charIndex+=2) { UChar codeUnit = (input[charIndex] << 8) | input[charIndex + 1]; if (charIndex == 0 && codeUnit == 0xFEFF) { confidence = 100; break; } confidence = adjustConfidence(codeUnit, confidence); if (confidence == 0 || confidence == 100) { break; } } if (bytesToCheck < 4 && confidence < 100) { confidence = 0; } results->set(textIn, this, confidence); return (confidence > 0); } CharsetRecog_UTF_16_LE::~CharsetRecog_UTF_16_LE() { // nothing to do } const char *CharsetRecog_UTF_16_LE::getName() const { return "UTF-16LE"; } UBool CharsetRecog_UTF_16_LE::match(InputText* textIn, CharsetMatch *results) const { const uint8_t *input = textIn->fRawInput; int32_t confidence = 10; int32_t length = textIn->fRawLength; int32_t bytesToCheck = (length > 30) ? 30 : length; for (int32_t charIndex=0; charIndex<bytesToCheck-1; charIndex+=2) { UChar codeUnit = input[charIndex] | (input[charIndex + 1] << 8); if (charIndex == 0 && codeUnit == 0xFEFF) { confidence = 100; // UTF-16 BOM if (length >= 4 && input[2] == 0 && input[3] == 0) { confidence = 0; // UTF-32 BOM } break; } confidence = adjustConfidence(codeUnit, confidence); if (confidence == 0 || confidence == 100) { break; } } if (bytesToCheck < 4 && confidence < 100) { confidence = 0; } results->set(textIn, this, confidence); return (confidence > 0); } CharsetRecog_UTF_32::~CharsetRecog_UTF_32() { // nothing to do } UBool CharsetRecog_UTF_32::match(InputText* textIn, CharsetMatch *results) const { const uint8_t *input = textIn->fRawInput; int32_t limit = (textIn->fRawLength / 4) * 4; int32_t numValid = 0; int32_t numInvalid = 0; bool hasBOM = FALSE; int32_t confidence = 0; if (limit > 0 && getChar(input, 0) == 0x0000FEFFUL) { hasBOM = TRUE; } for(int32_t i = 0; i < limit; i += 4) { int32_t ch = getChar(input, i); if (ch < 0 || ch >= 0x10FFFF || (ch >= 0xD800 && ch <= 0xDFFF)) { numInvalid += 1; } else { numValid += 1; } } // Cook up some sort of confidence score, based on presense of a BOM // and the existence of valid and/or invalid multi-byte sequences. if (hasBOM && numInvalid==0) { confidence = 100; } else if (hasBOM && numValid > numInvalid*10) { confidence = 80; } else if (numValid > 3 && numInvalid == 0) { confidence = 100; } else if (numValid > 0 && numInvalid == 0) { confidence = 80; } else if (numValid > numInvalid*10) { // Probably corruput UTF-32BE data. Valid sequences aren't likely by chance. confidence = 25; } results->set(textIn, this, confidence); return (confidence > 0); } CharsetRecog_UTF_32_BE::~CharsetRecog_UTF_32_BE() { // nothing to do } const char *CharsetRecog_UTF_32_BE::getName() const { return "UTF-32BE"; } int32_t CharsetRecog_UTF_32_BE::getChar(const uint8_t *input, int32_t index) const { return input[index + 0] << 24 | input[index + 1] << 16 | input[index + 2] << 8 | input[index + 3]; } CharsetRecog_UTF_32_LE::~CharsetRecog_UTF_32_LE() { // nothing to do } const char *CharsetRecog_UTF_32_LE::getName() const { return "UTF-32LE"; } int32_t CharsetRecog_UTF_32_LE::getChar(const uint8_t *input, int32_t index) const { return input[index + 3] << 24 | input[index + 2] << 16 | input[index + 1] << 8 | input[index + 0]; } U_NAMESPACE_END #endif