NAME¶
mconv_define_coding - Define a coding system.
SYNOPSIS¶
MSymbol mconv_define_coding (const char *
name,
MPlist *
plist, int(*)(
MConverter *)
resetter,
int(*)(const unsigned char *,
int,
MText *,
MConverter *)
decoder, int(*)(
MText *,
int,
int, unsigned char
*,
int,
MConverter *)
encoder, void *
extra_info)
DESCRIPTION¶
Define a coding system. The mconv_define_coding() function defines a new coding
system and makes it accessible via a symbol whose name is name
. plist
specifies parameters of the coding system as below:
- •
- Key is Mtype , value is a symbol
The value specifies the type of the coding system. It must be Mcharset
,
Mutf
, Miso_2022
, or Mnil
.
If the type is Mcharset
, extra_info is ignored.
If the type is Mutf
, extra_info must be a pointer to MCodingInfoUTF
.
If the type is Miso_2022
, extra_info must be a pointer to
MCodingInfoISO2022
.
If the type is Mnil
, the argument resetter
, decoder
, and
encoder must be supplied. extra_info is ignored. Otherwise, they can be NULL
and the m17n library provides proper defaults.
- •
- Key is Mcharsets , value is a plist
The value specifies a list charsets supported by the coding system. The keys of
the plist must be Msymbol
, and the values must be symbols representing
charsets.
- •
- Key is Mflags , value is a plist
If the type is Miso_2022
, the values specifies flags to control the ISO
2022 interpreter. The keys of the plist must e Msymbol
, and values
must be one of the following.
- •
- Mreset_at_eol
If this flag exists, designation and invocation status is reset to the initial
state at the end of line.
- •
- Mreset_at_cntl
If this flag exists, designation and invocation status is reset to the initial
state at a control character.
- •
- Meight_bit
If this flag exists, the graphic plane right is used.
- •
- Mlong_form
If this flag exists, the over-long escape sequences (ESC '$' '('
<final_byte>) are used for designating the CCS JISX0208.1978, GB2312,
and JISX0208.
- •
- Mdesignation_g0
If this flag and Mfull_support exists, designates charsets not listed in the
charset list to the graphic register G0.
- •
- Mdesignation_g1
If this flag and Mfull_support exists, designates charsets not listed in the
charset list to the graphic register G1.
- •
- Mdesignation_ctext
If this flag and Mfull_support exists, designates charsets not listed in the
charset list to a graphic register G0 or G1 based on the criteria of the
Compound Text.
- •
- Mdesignation_ctext_ext
If this flag and Mfull_support exists, designates charsets not listed in the
charset list to a graphic register G0 or G1, or use extended segment for such
charsets based on the criteria of the Compound Text.
- •
- Mlocking_shift
If this flag exists, use locking shift.
- •
- Msingle_shift
If this flag exists, use single shift.
- •
- Msingle_shift_7
If this flag exists, use 7-bit single shift code (0x19).
- •
- Meuc_tw_shift
If this flag exists, use a special shifting according to EUC-TW.
- •
- Miso_6429
This flag is currently ignored.
- •
- Mrevision_number
If this flag exists, use a revision number escape sequence to designate a
charset that has a revision number.
- •
- Mfull_support
If this flag exists, support all charsets registered in the International
Registry.
- •
- Key is Mdesignation , value is a plist
If the type is Miso_2022
, the value specifies how to designate each
supported characters. The keys of the plist must be Minteger
, and the
values must be numbers indicating a graphic registers. The Nth element value
is for the Nth charset of the charset list. The value 0..3 means that it is
assumed that a charset is already designated to the graphic register 0..3. The
negative value G (-4..-1) means that a charset is not designated to any
register at first, and if necessary, is designated to the (G+4) graphic
register.
- •
- Key is Minvocation , value is a plist
If the type is Miso_2022
, the value specifies how to invocate each
graphic registers. The plist length must be one or two. The keys of the plist
must be Minteger
, and the values must be numbers indicating a graphic
register. The value of the first element specifies which graphic register is
invocated to the graphic plane left. If the length is one, no graphic register
is invocated to the graphic plane right. Otherwise, the value of the second
element specifies which graphic register is invocated to the graphic plane
right.
- •
- Key is Mcode_unit , value is an integer
If the type is Mutf
, the value specifies the bit length of a code-unit.
It must be 8, 16, or 32.
- •
- Key is Mbom , value is a symbol
If the type is Mutf and the code-unit bit length is 16 or 32, it specifies
whether or not to use BOM (Byte Order Mark). If the value is Mnil (default),
BOM is not used, else if the value is Mmaybe
, the existence of BOM is
detected at decoding time, else BOM is used.
- •
- Key is Mlittle_endian , value is a symbol
If the type is Mutf and the code-unit bit length is 16 or 32, it specifies
whether or not the encoding is little endian. If the value is Mnil (default),
it is big endian, else it is little endian.
resetter is a pointer to a function that resets a converter for the
coding system to the initial status. The pointed function is called with one
argument, a pointer to a converter object.
decoder is a pointer to a function that decodes a byte sequence according
to the coding system. The pointed function is called with four arguments:
- •
- A pointer to the byte sequence to decode.
- •
- The number of bytes to decode.
- •
- A pointer to an M-text to which the decoded characters are
appended.
- •
- A pointer to a converter object.
decoder must return 0 if it succeeds. Otherwise it must return -1.
encoder is a pointer to a function that encodes an M-text according to
the coding system. The pointed function is called with six arguments:
- •
- A pointer to the M-text to encode.
- •
- The starting position of the encoding.
- •
- The ending position of the encoding.
- •
- A pointer to a memory area where the produced bytes are
stored.
- •
- The size of the memory area.
- •
- A pointer to a converter object.
encoder must return 0 if it succeeds. Otherwise it must return -1.
extra_info is a pointer to a data structure that contains extra
information about the coding system. The type of the data structure depends on
type
.
RETURN VALUE¶
If the operation was successful, mconv_define_coding() returns a symbol whose
name is name
. If an error is detected, it returns Mnil and assigns an
error code to the external variable merror_code
.
ERRORS¶
MERROR_CODING
COPYRIGHT¶
Copyright (C) 2001 Information-technology Promotion Agency (IPA)
Copyright (C) 2001-2011 National Institute of Advanced Industrial Science and
Technology (AIST)
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License
<
http://www.gnu.org/licenses/fdl.html>.