xref: /freebsd/lib/libc/locale/euc.5 (revision d8a0fe102c0cfdfcd5b818f850eff09d8536c9bc)
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4.\" This code is derived from software contributed to Berkeley by
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31.\"	@(#)euc.4	8.1 (Berkeley) 6/4/93
32.\" $FreeBSD$
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
67implements a system of 4 multibyte codesets.
68A multibyte character in the first codeset consists of
69.Ar len1
70bytes starting with a byte in the range of 0x00 to 0x7f.
71To allow use of
72.Tn ASCII ,
73.Ar len1
74is always 1.
75A multibyte character in the second codeset consists of
76.Ar len2
77bytes starting with a byte in the range of 0x80-0xff excluding 0x8e and 0x8f.
78A multibyte character in the third codeset consists of
79.Ar len3
80bytes starting with the byte 0x8e.
81A multibyte character in the fourth codeset consists of
82.Ar len4
83bytes starting with the byte 0x8f.
84.Pp
85The
86.Vt wchar_t
87encoding of
88.Nm EUC
89multibyte characters is dependent on the
90.Ar len
91and
92.Ar mask
93arguments.
94First, the bytes are moved into a
95.Vt wchar_t
96as follows:
97.Bd -literal
98byte0 << ((\fIlen\fPN-1) * 8) | byte1 << ((\fIlen\fPN-2) * 8) | ... | byte\fIlen\fPN-1
99.Ed
100.Pp
101The result is then ANDed with
102.Ar ~mask
103and ORed with
104.Ar maskN .
105Codesets 2 and 3 are special in that the leading byte (0x8e or 0x8f) is
106first removed and the
107.Ar lenN
108argument is reduced by 1.
109.Pp
110For example, the
111.Li ja_JP.eucJP
112locale has the following
113.Va VARIABLE
114line:
115.Bd -literal
116VARIABLE	1 0x0000 2 0x8080 2 0x0080 3 0x8000 0x8080
117.Ed
118.Pp
119Codeset 1 consists of the values 0x0000 - 0x007f.
120.Pp
121Codeset 2 consists of the values who have the bits 0x8080 set.
122.Pp
123Codeset 3 consists of the values 0x0080 - 0x00ff.
124.Pp
125Codeset 4 consists of the values 0x8000 - 0xff7f excluding the values
126which have the 0x0080 bit set.
127.Pp
128Notice that the global
129.Ar mask
130is set to 0x8080, this implies that from those 2 bits the codeset can
131be determined.
132.Sh SEE ALSO
133.Xr mklocale 1 ,
134.Xr setlocale 3
135