locale/FreeBSD/euc.5

   1 .\" Copyright (c) 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" This code is derived from software contributed to Berkeley by
   5 .\" Paul Borman at Krystal Technologies.
   6 .\"
   7 .\" Redistribution and use in source and binary forms, with or without
   8 .\" modification, are permitted provided that the following conditions
   9 .\" are met:
  10 .\" 1. Redistributions of source code must retain the above copyright
  11 .\"    notice, this list of conditions and the following disclaimer.
  12 .\" 2. Redistributions in binary form must reproduce the above copyright
  13 .\"    notice, this list of conditions and the following disclaimer in the
  14 .\"    documentation and/or other materials provided with the distribution.
  15 .\" 3. All advertising materials mentioning features or use of this software
  16 .\"    must display the following acknowledgement:
  17 .\"     This product includes software developed by the University of
  18 .\"     California, Berkeley and its contributors.
  19 .\" 4. Neither the name of the University nor the names of its contributors
  20 .\"    may be used to endorse or promote products derived from this software
  21 .\"    without specific prior written permission.
  22 .\"
  23 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33 .\" SUCH DAMAGE.
  34 .\"
  35 .\"     @(#)euc.4       8.1 (Berkeley) 6/4/93
  36 .\" $FreeBSD: src/lib/libc/locale/euc.5,v 1.12 2004/07/05 06:36:36 ru Exp $
  37 .\"
  38 .Dd November 8, 2003
  39 .Dt EUC 5
  40 .Os
  41 .Sh NAME
  42 .Nm euc
  43 .Nd EUC encoding of wide characters
  44 .Sh SYNOPSIS
  45 .Nm ENCODING
  46 .Qq EUC
  47 .Pp
  48 .Nm VARIABLE
  49 .Ar len1
  50 .Ar mask1
  51 .Ar len2
  52 .Ar mask2
  53 .Ar len3
  54 .Ar mask3
  55 .Ar len4
  56 .Ar mask4
  57 .Ar mask
  58 .Sh DESCRIPTION
  59 .\"The
  60 .\".Nm EUC
  61 .\"encoding is provided for compatibility with
  62 .\".Ux
  63 .\"based systems.
  64 .\"See
  65 .\".Xr mklocale 1
  66 .\"for a complete description of the
  67 .\".Ev LC_CTYPE
  68 .\"source file format.
  69 .\".Pp
  70 .Nm EUC
  71 implements a system of 4 multibyte codesets.
  72 A multibyte character in the first codeset consists of
  73 .Ar len1
  74 bytes starting with a byte in the range of 0x00 to 0x7f.
  75 To allow use of
  76 .Tn ASCII ,
  77 .Ar len1
  78 is always 1.
  79 A multibyte character in the second codeset consists of
  80 .Ar len2
  81 bytes starting with a byte in the range of 0x80-0xff excluding 0x8e and 0x8f.
  82 A multibyte character in the third codeset consists of
  83 .Ar len3
  84 bytes starting with the byte 0x8e.
  85 A multibyte character in the fourth codeset consists of
  86 .Ar len4
  87 bytes starting with the byte 0x8f.
  88 .Pp
  89 The
  90 .Vt wchar_t
  91 encoding of
  92 .Nm EUC
  93 multibyte characters is dependent on the
  94 .Ar len
  95 and
  96 .Ar mask
  97 arguments.
  98 First, the bytes are moved into a
  99 .Vt wchar_t
 100 as follows:
 101 .Bd -literal
 102 byte0 << ((\fIlen\fPN-1) * 8) | byte1 << ((\fIlen\fPN-2) * 8) | ... | byte\fIlen\fPN-1
 103 .Ed
 104 .Pp
 105 The result is then ANDed with
 106 .Ar ~mask
 107 and ORed with
 108 .Ar maskN .
 109 Codesets 2 and 3 are special in that the leading byte (0x8e or 0x8f) is
 110 first removed and the
 111 .Ar lenN
 112 argument is reduced by 1.
 113 .Pp
 114 For example, the
 115 .Li ja_JP.eucJP
 116 locale has the following
 117 .Va VARIABLE
 118 line:
 119 .Bd -literal
 120 VARIABLE        1 0x0000 2 0x8080 2 0x0080 3 0x8000 0x8080
 121 .Ed
 122 .Pp
 123 Codeset 1 consists of the values 0x0000 - 0x007f.
 124 .Pp
 125 Codeset 2 consists of the values who have the bits 0x8080 set.
 126 .Pp
 127 Codeset 3 consists of the values 0x0080 - 0x00ff.
 128 .Pp
 129 Codeset 4 consists of the values 0x8000 - 0xff7f excluding the values
 130 which have the 0x0080 bit set.
 131 .Pp
 132 Notice that the global
 133 .Ar mask
 134 is set to 0x8080, this implies that from those 2 bits the codeset can
 135 be determined.
 136 .Sh SEE ALSO
 137 .Xr mklocale 1 ,
 138 .Xr setlocale 3