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scsuutf8.cpp

/******************************************************************************
 *
 * SCSUUTF8 -   SWFilter decendant to convert a SCSU character to UTF-8
 *
 */


/* This class is based on:
 * http://czyborra.com/scsu/scsu.c written by Roman Czyborra@dds.nl
 * on Andrea's balcony in North Amsterdam on 1998-08-04
 * Thanks to Richard Verhoeven <rcb5@win.tue.nl> for his suggestion
 * to correct the haphazard "if" after UQU to "else if" on 1998-10-01
 * 
 * This is a deflator to UTF-8 output for input compressed in SCSU,
 * the (Reuters) Standard Compression Scheme for Unicode as described
 * in http://www.unicode.org/unicode/reports/tr6.html
 */

#include <stdlib.h>
#include <stdio.h>
#include <swmodule.h>

#include <scsuutf8.h>

SCSUUTF8::SCSUUTF8() {
}


unsigned char* SCSUUTF8::UTF8Output(unsigned long uchar, unsigned char* text)
{
  /* join UTF-16 surrogates without any pairing sanity checks */

  static int d;
  
  if (uchar >= 0xd800 && uchar <= 0xdbff) { d = uchar & 0x3f; return text;  }
  if (uchar >= 0xdc00 && uchar <= 0xdfff) { uchar = uchar + 0x2400 + d * 0x400; }
  
  /* output one character as UTF-8 multibyte sequence */
  
  if (uchar < 0x80) {
    *text++ = c;
  }
  else if (uchar < 0x800) { 
    *text++ = 0xc0 | uchar >> 6; 
    *text++ = 0x80 | uchar & 0x3f;
  }
  else if (uchar < 0x10000) {
    *text++ = 0xe0 | uchar >> 12; 
    *text++ = 0x80 | uchar >> 6 & 0x3f;
    *text++ = 0x80 | uchar & 0x3f;
  }
  else if (uchar < 0x200000) {
    *text++ = 0xf0 | uchar >> 18;
    *text++ = 0x80 | uchar >> 12 & 0x3f; 
    *text++ = 0x80 | uchar >> 6 & 0x3f; 
    *text++ = 0x80 | uchar & 0x3f;
  }  
  
  return text;
}

char SCSUUTF8::ProcessText(char *text, int len, const SWKey *key, const SWModule *module)
{
  unsigned char *to, *from;
  unsigned long buflen = len * FILTERPAD;
  char active = 0, mode = 0;

  static unsigned short start[8] = {0x0000,0x0080,0x0100,0x0300,0x2000,0x2080,0x2100,0x3000};
  static unsigned short slide[8] = {0x0080,0x00C0,0x0400,0x0600,0x0900,0x3040,0x30A0,0xFF00};
  static unsigned short win[256]   = {
    0x0000, 0x0080, 0x0100, 0x0180, 0x0200, 0x0280, 0x0300, 0x0380,
    0x0400, 0x0480, 0x0500, 0x0580, 0x0600, 0x0680, 0x0700, 0x0780,
    0x0800, 0x0880, 0x0900, 0x0980, 0x0A00, 0x0A80, 0x0B00, 0x0B80,
    0x0C00, 0x0C80, 0x0D00, 0x0D80, 0x0E00, 0x0E80, 0x0F00, 0x0F80,
    0x1000, 0x1080, 0x1100, 0x1180, 0x1200, 0x1280, 0x1300, 0x1380,
    0x1400, 0x1480, 0x1500, 0x1580, 0x1600, 0x1680, 0x1700, 0x1780,
    0x1800, 0x1880, 0x1900, 0x1980, 0x1A00, 0x1A80, 0x1B00, 0x1B80,
    0x1C00, 0x1C80, 0x1D00, 0x1D80, 0x1E00, 0x1E80, 0x1F00, 0x1F80,
    0x2000, 0x2080, 0x2100, 0x2180, 0x2200, 0x2280, 0x2300, 0x2380,
    0x2400, 0x2480, 0x2500, 0x2580, 0x2600, 0x2680, 0x2700, 0x2780,
    0x2800, 0x2880, 0x2900, 0x2980, 0x2A00, 0x2A80, 0x2B00, 0x2B80,
    0x2C00, 0x2C80, 0x2D00, 0x2D80, 0x2E00, 0x2E80, 0x2F00, 0x2F80,
    0x3000, 0x3080, 0x3100, 0x3180, 0x3200, 0x3280, 0x3300, 0x3800,
    0xE000, 0xE080, 0xE100, 0xE180, 0xE200, 0xE280, 0xE300, 0xE380,
    0xE400, 0xE480, 0xE500, 0xE580, 0xE600, 0xE680, 0xE700, 0xE780,
    0xE800, 0xE880, 0xE900, 0xE980, 0xEA00, 0xEA80, 0xEB00, 0xEB80,
    0xEC00, 0xEC80, 0xED00, 0xED80, 0xEE00, 0xEE80, 0xEF00, 0xEF80,
    0xF000, 0xF080, 0xF100, 0xF180, 0xF200, 0xF280, 0xF300, 0xF380,
    0xF400, 0xF480, 0xF500, 0xF580, 0xF600, 0xF680, 0xF700, 0xF780,
    0xF800, 0xF880, 0xF900, 0xF980, 0xFA00, 0xFA80, 0xFB00, 0xFB80,
    0xFC00, 0xFC80, 0xFD00, 0xFD80, 0xFE00, 0xFE80, 0xFF00, 0xFF80,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
    0x0000, 0x00C0, 0x0250, 0x0370, 0x0530, 0x3040, 0x30A0, 0xFF60
  };

  if (!len)
        return 0;

  memmove(&text[buflen - len], text, len);
  from = (unsigned char*)&text[buflen - len];
  to = (unsigned char *)text;

  // -------------------------------

  for (int i = 0; i < len;) {


      if (i >= len) break;
      c = from[i++];

      if (c >= 0x80)
        {
          to = UTF8Output (c - 0x80 + slide[active], to);
        }
      else if (c >= 0x20 && c <= 0x7F)
        {
          to = UTF8Output (c, to);
        }
      else if (c == 0x0 || c == 0x9 || c == 0xA || c == 0xC || c == 0xD)
        {
          to = UTF8Output (c, to);
        }
      else if (c >= 0x1 && c <= 0x8) /* SQn */
        {
          if (i >= len) break;
          /* single quote */ d = from[i++];

          to = UTF8Output (d < 0x80 ? d + start [c - 0x1] :
                  d - 0x80 + slide [c - 0x1], to);
        }
      else if (c >= 0x10 && c <= 0x17) /* SCn */
        {
          /* change window */ active = c - 0x10;
        }
      else if (c >= 0x18 && c <= 0x1F) /* SDn */
        {
          /* define window */ active = c - 0x18;
          if (i >= len) break;
          slide [active] = win [from[i++]];
        }
      else if (c == 0xB) /* SDX */
        {
          if (i >= len) break;
          c = from[i++];

          if (i >= len) break;
          d = from[i++];

          slide [active = c>>5] = 0x10000 + (((c & 0x1F) << 8 | d) << 7);
        }
      else if (c == 0xE) /* SQU */
        {
          if (i >= len) break;
          /* SQU */ c = from[i++];

          if (i >= len) break;
          to = UTF8Output (c << 8 | from[i++], to);
        }
      else if (c == 0xF) /* SCU */
        {
          /* change to Unicode mode */ mode = 1;

          while (mode)
            {
              if (i >= len) break;
              c = from[i++];

              if (c <= 0xDF || c >= 0xF3)
                {
                  if (i >= len) break;
                  to = UTF8Output (c << 8 | from[i++], to);
                }
              else if (c == 0xF0) /* UQU */
                {
                  if (i >= len) break;
                  c = from[i++];

                  if (i >= len) break;
                  to = UTF8Output (c << 8 | from[i++], to);
                }
              else if (c >= 0xE0 && c <= 0xE7) /* UCn */
                {
                  active = c - 0xE0; mode = 0;
                }
              else if (c >= 0xE8 && c <= 0xEF) /* UDn */
                {
                  if (i >= len) break;
                  slide [active=c-0xE8] = win [from[i++]]; mode = 0;
                }
              else if (c == 0xF1) /* UDX */
                {
                  if (i >= len) break;
                  c = from[i++];

                  if (i >= len) break;
                  d = from[i++];

                  slide [active = c>>5] =
                    0x10000 + (((c & 0x1F) << 8 | d) << 7); mode = 0;
                }
            }
        }


  }

  *to++ = 0;
  *to = 0;
  return 0;
}

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