source/jisx0208.cpp

   1 /* $Id$
   2
   3 This file is part of libmspstrings
   4 Copyright © 2006-2007 Mikko Rasa
   5 Distributed under the LGPL
   6 */
   7
   8 #include "jisx0208.h"
   9
  10 #include "jisx0208.table"
  11
  12 using namespace std;
  13
  14 namespace Msp {
  15
  16 void JisX0208::Encoder::encode_char(wchar_t ucs)
  17 {
  18         unsigned short jis=ucs_to_jisx0208(ucs);
  19         if(jis)
  20         {
  21                 char buf[2]={jis>>8, jis};
  22                 append(buf, 2);
  23         }
  24         else
  25                 error("Can't express character in JIS X 0208");
  26 }
  27
  28
  29 void JisX0208::Decoder::decode_char(const string &str, string::const_iterator &i)
  30 {
  31         if(i==str.end())
  32                 return;
  33
  34         if(!high)
  35                 high=*i++;
  36
  37         if(i==str.end())
  38                 return;
  39
  40         wchar_t ucs=jisx0208_to_ucs(high<<8 | *i++);
  41         high=0;
  42
  43         if(ucs)
  44                 append(ucs);
  45         else
  46                 error("Invalid JIS X 0208 string (undefined character)");
  47 }
  48
  49 void JisX0208::Decoder::sync()
  50 {
  51         if(high)
  52         {
  53                 error("Sync in middle of JIS X 0208 character");
  54                 high=0;
  55         }
  56 }
  57
  58 wchar_t jisx0208_to_ucs(unsigned short jis)
  59 {
  60         if((jis&0xFF)<0x21 || (jis&0xFF)>0x7E || (jis&0xFF00)<0x2100 || (jis&0xFF00)>0x7E00)
  61                 return 0;
  62
  63         return jisx0208_to_ucs_table[((jis>>8)&0xFF)*94 + (jis&0xFF)-0x21*95];
  64 }
  65
  66 unsigned short ucs_to_jisx0208(wchar_t c)
  67 {
  68         if(c&0xFFFF0000) return 0;
  69
  70         unsigned i=0;
  71         for(unsigned bit=0x1000; bit; bit>>=1)
  72         {
  73                 if(i+bit>=ucs_to_jisx0208_table_size)
  74                         continue;
  75                 if(ucs_to_jisx0208_table[i+bit].ucs<=static_cast<unsigned short>(c))
  76                         i+=bit;
  77         }
  78
  79         if(ucs_to_jisx0208_table[i].ucs==static_cast<unsigned short>(c))
  80                 return ucs_to_jisx0208_table[i].jis;
  81         return 0;
  82 }
  83
  84 } // namespace Msp