kc3-lang/libxml2/encoding.c

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• Hash : 0ba4d537
  Author :
  Date : 1998-11-01T19:34:31
  

  CharRef handling, comments, formatting, pre UTF-8 handling, Daniel.
  

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• encoding.c

• /*
   * encoding.c : implements the encoding conversion functions needed for XML
   *
   * Related specs: 
   * rfc2044        (UTF-8 and UTF-16) F. Yergeau Alis Technologies
   * [ISO-10646]    UTF-8 and UTF-16 in Annexes
   * [ISO-8859-1]   ISO Latin-1 characters codes.
   * [UNICODE]      The Unicode Consortium, "The Unicode Standard --
   *                Worldwide Character Encoding -- Version 1.0", Addison-
   *                Wesley, Volume 1, 1991, Volume 2, 1992.  UTF-8 is
   *                described in Unicode Technical Report #4.
   * [US-ASCII]     Coded Character Set--7-bit American Standard Code for
   *                Information Interchange, ANSI X3.4-1986.
   *
   * Original code from "Martin J. Duerst" <duerst@w3.org>
   *
   * See Copyright for the status of this software.
   *
   * $Id$
   *
   * Daniel.Veillard@w3.org
   */
  
  #include "encoding.h"
  
  /*
   * From rfc2044: encoding of the Unicode values on UTF-8:
   *
   * UCS-4 range (hex.)           UTF-8 octet sequence (binary)
   * 0000 0000-0000 007F   0xxxxxxx
   * 0000 0080-0000 07FF   110xxxxx 10xxxxxx
   * 0000 0800-0000 FFFF   1110xxxx 10xxxxxx 10xxxxxx 
   *
   * I hope we won't use values > 0xFFFF anytime soon !
   */
  
  /**
   * isolat1ToUTF8:
   * @out:  a pointer ot an array of bytes to store the result
   * @outlen:  the lenght of @out
   * @in:  a pointer ot an array of ISO Latin 1 chars
   * @inlen:  the lenght of @in
   *
   * Take a block of ISO Latin 1 chars in and try to convert it to an UTF-8
   * block of chars out.
   * return values: number of byte written, or -1 by lack of space.
   */
  int
  isolat1ToUTF8(unsigned char* out, int outlen, unsigned char* in, int inlen)
  {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      unsigned char* inend= in+inlen;
      unsigned char c;
  
      while (in < inend) {
          c= *in++;
          if (c < 0x80) {
              if (out >= outend)  return -1;
              *out++ = c;
          }
          else {
              if (out >= outend)  return -1;
              *out++ = 0xC0 | (c >> 6);
              if (out >= outend)  return -1;
              *out++ = 0x80 | (0x3F & c);
          }
      }
      return out-outstart;
  }
  
  /**
   * UTF8Toisolat1:
   * @out:  a pointer ot an array of bytes to store the result
   * @outlen:  the lenght of @out
   * @in:  a pointer ot an array of UTF-8 chars
   * @inlen:  the lenght of @in
   *
   * Take a block of UTF-8 chars in and try to convert it to an ISO Latin 1
   * block of chars out.
   * TODO: need a fallback mechanism ...
   * return values: the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding failed.
   */
  int
  UTF8Toisolat1(unsigned char* out, int outlen, unsigned char* in, int inlen)
  {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      unsigned char* inend= in+inlen;
      unsigned char c;
  
      while (in < inend) {
          c= *in++;
          if (c < 0x80) {
              if (out >= outend)  return -1;
              *out++= c;
          }
          else if (((c & 0xFE) == 0xC2) && in<inend) {
              if (out >= outend)  return -1;
              *out++= ((c & 0x03) << 6) | (*in++ & 0x3F);
          }
          else  return -2;
      }
      return out-outstart;
  }
  
  /**
   * UTF16ToUTF8:
   * @out:  a pointer ot an array of bytes to store the result
   * @outlen:  the lenght of @out
   * @in:  a pointer ot an array of UTF-16 chars (array of unsigned shorts)
   * @inlen:  the lenght of @in
   *
   * Take a block of UTF-16 ushorts in and try to convert it to an UTF-8
   * block of chars out.
   * return values: number of byte written, or -1 by lack of space.
   */
  int
  UTF16ToUTF8(unsigned char* out, int outlen, unsigned short* in, int inlen)
  {
      unsigned char* outstart= out;
      unsigned char* outend= out+outlen;
      unsigned short* inend= in+inlen;
      unsigned int c, d;
      int bits;
  
      while (in < inend) {
          c= *in++;
          if ((c & 0xFC00) == 0xD800) {    /* surrogates */
              if ((in<inend) && (((d=*in++) & 0xFC00) == 0xDC00)) {
                  c &= 0x03FF;
                  c <<= 10;
                  c |= d & 0x03FF;
                  c += 0x10000;
              }
              else  return -1;
          }
  
        /* assertion: c is a single UTF-4 value */
  
          if (out >= outend)  return -1;
          if      (c <    0x80) {  *out++=  c;                bits= -6; }
          else if (c <   0x800) {  *out++= (c >>  6) | 0xC0;  bits=  0; }
          else if (c < 0x10000) {  *out++= (c >> 12) | 0xE0;  bits=  6; }
          else                  {  *out++= (c >> 18) | 0xF0;  bits= 12; }
   
          for ( ; bits < 0; bits-= 6) {
              if (out >= outend)  return -1;
              *out++= (c >> bits) & 0x3F;
          }
      }
      return out-outstart;
  }
  
  /**
   * UTF8ToUTF16:
   * @out:  a pointer ot an array of shorts to store the result
   * @outlen:  the lenght of @out (number of shorts)
   * @in:  a pointer ot an array of UTF-8 chars
   * @inlen:  the lenght of @in
   *
   * Take a block of UTF-8 chars in and try to convert it to an UTF-16
   * block of chars out.
   * TODO: need a fallback mechanism ...
   * return values: the number of byte written, or -1 by lack of space, or -2
   *     if the transcoding failed.
   */
  int
  UTF8ToUTF16(unsigned short* out, int outlen, unsigned char* in, int inlen)
  {
      unsigned short* outstart= out;
      unsigned short* outend= out+outlen;
      unsigned char* inend= in+inlen;
      unsigned int c, d, trailing;
  
      while (in < inend) {
        d= *in++;
        if      (d < 0x80)  { c= d; trailing= 0; }
        else if (d < 0xC0)  return -2;    /* trailing byte in leading position */
        else if (d < 0xE0)  { c= d & 0x1F; trailing= 1; }
        else if (d < 0xF0)  { c= d & 0x0F; trailing= 2; }
        else if (d < 0xF8)  { c= d & 0x07; trailing= 3; }
        else return -2;    /* no chance for this in UTF-16 */
  
        for ( ; trailing; trailing--) {
            if ((in >= inend) || (((d= *in++) & 0xC0) != 0x80))  return -1;
            c <<= 6;
            c |= d & 0x3F;
        }
  
        /* assertion: c is a single UTF-4 value */
          if (c < 0x10000) {
              if (out >= outend)  return -1;
              *out++ = c;
          }
          else if (c < 0x110000) {
              if (out+1 >= outend)  return -1;
              c -= 0x10000;
              *out++ = 0xD800 | (c >> 10);
              *out++ = 0xDC00 | (c & 0x03FF);
          }
          else  return -1;
      }
      return out-outstart;
  }
  
  
  

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