text: /*
   **********************************************************************
   *   Copyright (C) 2005-2012, 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";
  }
  
  UBool CharsetRecog_UTF_16_BE::match(InputText* textIn, CharsetMatch *results) const
  {
      const uint8_t *input = textIn->fRawInput;
      int32_t confidence = 0;
  
      if (input[0] == 0xFE && input[1] == 0xFF) {
          confidence = 100;
      }
  
      // TODO: Do some statastics to check for unsigned UTF-16BE
      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 = 0;
  
      if (input[0] == 0xFF && input[1] == 0xFE && (input[2] != 0x00 || input[3] != 0x00)) {
          confidence = 100;
      }
  
      // TODO: Do some statastics to check for unsigned UTF-16LE
      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 (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
  
  