locale/FreeBSD/euc.5

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   4 .\" This code is derived from software contributed to Berkeley by
   5 .\" Paul Borman at Krystal Technologies.
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  31 .\"     @(#)euc.4       8.1 (Berkeley) 6/4/93
  32 .\" $FreeBSD: src/lib/libc/locale/euc.5,v 1.13 2007/01/09 00:28:00 imp Exp $
  33 .\"
  34 .Dd November 8, 2003
  35 .Dt EUC 5
  36 .Os
  37 .Sh NAME
  38 .Nm euc
  39 .Nd EUC encoding of wide characters
  40 .Sh SYNOPSIS
  41 .Nm ENCODING
  42 .Qq EUC
  43 .Pp
  44 .Nm VARIABLE
  45 .Ar len1
  46 .Ar mask1
  47 .Ar len2
  48 .Ar mask2
  49 .Ar len3
  50 .Ar mask3
  51 .Ar len4
  52 .Ar mask4
  53 .Ar mask
  54 .Sh DESCRIPTION
  55 .\"The
  56 .\".Nm EUC
  57 .\"encoding is provided for compatibility with
  58 .\".Ux
  59 .\"based systems.
  60 .\"See
  61 .\".Xr mklocale 1
  62 .\"for a complete description of the
  63 .\".Ev LC_CTYPE
  64 .\"source file format.
  65 .\".Pp
  66 .Nm EUC
  67 implements a system of 4 multibyte codesets.
  68 A multibyte character in the first codeset consists of
  69 .Ar len1
  70 bytes starting with a byte in the range of 0x00 to 0x7f.
  71 To allow use of
  72 .Tn ASCII ,
  73 .Ar len1
  74 is always 1.
  75 A multibyte character in the second codeset consists of
  76 .Ar len2
  77 bytes starting with a byte in the range of 0x80-0xff excluding 0x8e and 0x8f.
  78 A multibyte character in the third codeset consists of
  79 .Ar len3
  80 bytes starting with the byte 0x8e.
  81 A multibyte character in the fourth codeset consists of
  82 .Ar len4
  83 bytes starting with the byte 0x8f.
  84 .Pp
  85 The
  86 .Vt wchar_t
  87 encoding of
  88 .Nm EUC
  89 multibyte characters is dependent on the
  90 .Ar len
  91 and
  92 .Ar mask
  93 arguments.
  94 First, the bytes are moved into a
  95 .Vt wchar_t
  96 as follows:
  97 .Bd -literal
  98 byte0 << ((\fIlen\fPN-1) * 8) | byte1 << ((\fIlen\fPN-2) * 8) | ... | byte\fIlen\fPN-1
  99 .Ed
 100 .Pp
 101 The result is then ANDed with
 102 .Ar ~mask
 103 and ORed with
 104 .Ar maskN .
 105 Codesets 2 and 3 are special in that the leading byte (0x8e or 0x8f) is
 106 first removed and the
 107 .Ar lenN
 108 argument is reduced by 1.
 109 .Pp
 110 For example, the
 111 .Li ja_JP.eucJP
 112 locale has the following
 113 .Va VARIABLE
 114 line:
 115 .Bd -literal
 116 VARIABLE        1 0x0000 2 0x8080 2 0x0080 3 0x8000 0x8080
 117 .Ed
 118 .Pp
 119 Codeset 1 consists of the values 0x0000 - 0x007f.
 120 .Pp
 121 Codeset 2 consists of the values who have the bits 0x8080 set.
 122 .Pp
 123 Codeset 3 consists of the values 0x0080 - 0x00ff.
 124 .Pp
 125 Codeset 4 consists of the values 0x8000 - 0xff7f excluding the values
 126 which have the 0x0080 bit set.
 127 .Pp
 128 Notice that the global
 129 .Ar mask
 130 is set to 0x8080, this implies that from those 2 bits the codeset can
 131 be determined.
 132 .Sh SEE ALSO
 133 .Xr mklocale 1 ,
 134 .Xr setlocale 3