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[bpt/emacs.git] / src / coding.h

/* Header for coding system handler.
   Copyright (C) 1995, 1997 Electrotechnical Laboratory, JAPAN.
   Licensed to the Free Software Foundation.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#ifndef _CODING_H
#define _CODING_H

#ifndef _CCL_H
#include "../src/ccl.h"
#endif

/*** EMACS' INTERNAL FORMAT (emacs-mule) section ***/

/* All code (1-byte) of Emacs' internal format is classified into one
   of the followings.  See also `charset.h'.  */
enum emacs_code_class_type
  {
    EMACS_control_code,		/* Control codes in the range
				   0x00..0x1F and 0x7F except for the
				   following two codes.  */
    EMACS_linefeed_code,	/* 0x0A (linefeed) to denote
				   end-of-line.  */
    EMACS_carriage_return_code,	/* 0x0D (carriage-return) to be used
				   in selective display mode.  */
    EMACS_ascii_code,		/* ASCII characters.  */
    EMACS_leading_code_composition, /* Leading code of a composite
				       character.  */
    EMACS_leading_code_2,	/* Base leading code of official
				   TYPE9N character.  */
    EMACS_leading_code_3,	/* Base leading code of private TYPE9N
				   or official TYPE9Nx9N character.  */
    EMACS_leading_code_4,	/* Base leading code of private
				   TYPE9Nx9N character.  */
    EMACS_invalid_code		/* Invalid code, i.e. a base leading
				   code not yet assigned to any
				   charset, or a code of the range
				   0xA0..0xFF.  */
  };

extern enum emacs_code_class_type emacs_code_class[256];

/*** ISO2022 section ***/

/* Macros to define code of control characters for ISO2022's functions.  */
			/* code */	/* function */
#define ISO_CODE_LF	0x0A		/* line-feed */
#define ISO_CODE_CR	0x0D		/* carriage-return */
#define ISO_CODE_SO	0x0E		/* shift-out */
#define ISO_CODE_SI	0x0F		/* shift-in */
#define ISO_CODE_SS2_7	0x19		/* single-shift-2 for 7-bit code */
#define ISO_CODE_ESC	0x1B		/* escape */
#define ISO_CODE_SS2	0x8E		/* single-shift-2 */
#define ISO_CODE_SS3	0x8F		/* single-shift-3 */
#define ISO_CODE_CSI	0x9B		/* control-sequence-introduce */

/* All code (1-byte) of ISO2022 is classified into one of the
   followings.  */
enum iso_code_class_type
  {
    ISO_control_code,		/* Control codes in the range
				   0x00..0x1F, 0x7F, and 0x80..0x9F,
				   except for the following seven
				   codes.  */
    ISO_carriage_return,	/* ISO_CODE_CR (0x0D) */
    ISO_shift_out,		/* ISO_CODE_SO (0x0E) */
    ISO_shift_in,		/* ISO_CODE_SI (0x0F) */
    ISO_single_shift_2_7,	/* ISO_CODE_SS2_7 (0x19) */
    ISO_escape,			/* ISO_CODE_SO (0x1B) */
    ISO_single_shift_2,		/* ISO_CODE_SS2 (0x8E) */
    ISO_single_shift_3,		/* ISO_CODE_SS3 (0x8F) */
    ISO_control_sequence_introducer, /* ISO_CODE_CSI (0x9B) */
    ISO_0x20_or_0x7F,		/* Codes of the values 0x20 or 0x7F.  */
    ISO_graphic_plane_0,	/* Graphic codes in the range 0x21..0x7E.  */
    ISO_0xA0_or_0xFF,		/* Codes of the values 0xA0 or 0xFF.  */
    ISO_graphic_plane_1		/* Graphic codes in the range 0xA1..0xFE.  */
  };

/** The macros CODING_FLAG_ISO_XXX defines a flag bit of the `flags'
  element in the structure `coding_system'.  This information is used
  while encoding a text to ISO2022.  **/

/* If set, produce short-form designation sequence (e.g. ESC $ A)
   instead of long-form sequence (e.g. ESC $ ( A).  */
#define CODING_FLAG_ISO_SHORT_FORM	0x0001

/* If set, reset graphic planes and registers at end-of-line to the
   initial state.  */
#define CODING_FLAG_ISO_RESET_AT_EOL	0x0002

/* If set, reset graphic planes and registers before any control
   characters to the initial state.  */
#define CODING_FLAG_ISO_RESET_AT_CNTL	0x0004

/* If set, encode by 7-bit environment.  */
#define CODING_FLAG_ISO_SEVEN_BITS	0x0008

/* If set, use locking-shift function.  */
#define CODING_FLAG_ISO_LOCKING_SHIFT	0x0010

/* If set, use single-shift function.  Overwrite
   CODING_FLAG_ISO_LOCKING_SHIFT.  */
#define CODING_FLAG_ISO_SINGLE_SHIFT	0x0020

/* If set, designate JISX0201-Roman instead of ASCII.  */
#define CODING_FLAG_ISO_USE_ROMAN	0x0040

/* If set, designate JISX0208-1978 instead of JISX0208-1983.  */
#define CODING_FLAG_ISO_USE_OLDJIS	0x0080

/* If set, do not produce ISO6429's direction specifying sequence.  */
#define CODING_FLAG_ISO_NO_DIRECTION	0x0100

/* If set, assume designation states are reset at beginning of line on
   output.  */
#define CODING_FLAG_ISO_INIT_AT_BOL	0x0200

/* If set, designation sequence should be placed at beginning of line
   on output.  */
#define CODING_FLAG_ISO_DESIGNATE_AT_BOL 0x0400

/* If set, do not encode unexpected charactes on output.  */
#define CODING_FLAG_ISO_SAFE		0x0800

/* A character to be produced on output if encoding of the original
   character is prohibited by CODING_FLAG_ISO_SAFE.  */
#define CODING_INHIBIT_CHARACTER_SUBSTITUTION  077 /* `?' */

/* Structure of the field `spec.iso2022' in the structure `coding_system'.  */
struct iso2022_spec
{
  /* The current graphic register invoked to each graphic plane.  */
  int current_invocation[2];

  /* The current charset designated to each graphic register.  */
  int current_designation[4];

  /* A charset initially designated to each graphic register.  */
  int initial_designation[4];

  /* A graphic register to which each charset should be designated.  */
  unsigned char requested_designation[MAX_CHARSET + 1];

  /* Table of expected character sets for this coding system.  If the
     Nth element is 0, the charset of ID N is not an expected
     character set.  Such a character set is not encoded when
     CODING_ISO_FLAG_SAFE is set.  */
  unsigned char expected_charsets[MAX_CHARSET + 1];

  /* Set to 1 temporarily only when graphic register 2 or 3 is invoked
     by single-shift while encoding.  */
  int single_shifting;

  /* Set to 1 temporarily only when processing at beginning of line.  */
  int bol;
};

/* Macros to access each field in the structure `spec.iso2022'.  */
#define CODING_SPEC_ISO_INVOCATION(coding, plane) \
  coding->spec.iso2022.current_invocation[plane]
#define CODING_SPEC_ISO_DESIGNATION(coding, reg) \
  coding->spec.iso2022.current_designation[reg]
#define CODING_SPEC_ISO_INITIAL_DESIGNATION(coding, reg) \
  coding->spec.iso2022.initial_designation[reg]
#define CODING_SPEC_ISO_REQUESTED_DESIGNATION(coding, charset) \
  coding->spec.iso2022.requested_designation[charset]
#define CODING_SPEC_ISO_EXPECTED_CHARSETS(coding) \
  coding->spec.iso2022.expected_charsets
#define CODING_SPEC_ISO_SINGLE_SHIFTING(coding) \
  coding->spec.iso2022.single_shifting
#define CODING_SPEC_ISO_BOL(coding) \
  coding->spec.iso2022.bol

/* A value which may appear in
   coding->spec.iso2022.requested_designation indicating that the
   corresponding charset does not request any graphic register to be
   designated.  */
#define CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION 4

/* Return a charset which is currently designated to the graphic plane
   PLANE in the coding-system CODING.  */
#define CODING_SPEC_ISO_PLANE_CHARSET(coding, plane)	\
  ((CODING_SPEC_ISO_INVOCATION (coding, plane) < 0)	\
   ? -1							\
   : CODING_SPEC_ISO_DESIGNATION (coding,		\
				  CODING_SPEC_ISO_INVOCATION (coding, plane)))

/*** BIG5 section ***/

/* Macros to denote each type of BIG5 coding system.  */
#define CODING_FLAG_BIG5_HKU	0x00 /* BIG5-HKU is one of variants of
					BIG5 developed by Hong Kong
					University.  */
#define CODING_FLAG_BIG5_ETEN	0x01 /* BIG5_ETen is one of variants
					of BIG5 developed by the
					company ETen in Taiwan.  */

/*** GENERAL section ***/

/* Types of coding system.  */
enum coding_type
  {
    coding_type_no_conversion,	/* A coding system which requires no
				   conversion for reading and writing
				   including end-of-line format.  */
    coding_type_emacs_mule,	/* A coding system used in Emacs'
				   buffer and string.  Requires no
				   conversion for reading and writing
				   except for end-of-line format.  */
    coding_type_undecided,	/* A coding system which requires
				   automatic detection of a real
				   coding system.  */
    coding_type_sjis,		/* SJIS coding system for Japanese.  */
    coding_type_iso2022,	/* Any coding system of ISO2022
				   variants.  */
    coding_type_big5,		/* BIG5 coding system for Chinese.  */
    coding_type_ccl		/* The coding system of which decoder
				   and encoder are written in CCL.  */
  };

/* Formats of end-of-line.  */
#define CODING_EOL_LF	0	/* Line-feed only, same as Emacs'
				   internal format.  */
#define CODING_EOL_CRLF	1	/* Sequence of carriage-return and
				   line-feed.  */
#define CODING_EOL_CR	2	/* Carriage-return only.  */
#define CODING_EOL_UNDECIDED 3	/* This value is used to denote the
				   eol-type is not yet decided.  */

/* Character composition status while encoding/decoding.  */
#define COMPOSING_NO		 0 /* not composing */
#define COMPOSING_WITH_RULE_HEAD 1 /* 1st char of with-rule composing follow */
#define COMPOSING_NO_RULE_HEAD	 2 /* 1st char of no-rule composing follow */
#define COMPOSING_WITH_RULE_TAIL 3 /* Nth char of with-rule composing follow */
#define COMPOSING_NO_RULE_TAIL	 4 /* Nth char of no-rule composing follow */
#define COMPOSING_WITH_RULE_RULE 5 /* composition rule follow */

/* 1 iff composing.  */
#define COMPOSING_P(composing) (composing)
/* 1 iff 1st char of composing element follows.  */
#define COMPOSING_HEAD_P(composing) \
  ((composing) && (composing) <= COMPOSING_NO_RULE_HEAD)
/* 1 iff composing with embeded composition rule.  */
#define COMPOSING_WITH_RULE_P(composing) ((composing) & 1)

struct coding_system
{
  /* Type of the coding system.  */
  enum coding_type type;

  /* If the coding system requires specific code to be attached at the
     tail of converted text, this value should be set to `1'.  */
  int require_flushing;

  /* Flag bits of the coding system.  The meaning of each bit depends
     on the type of the coding system.  */
  unsigned int flags;

  /* Type of end-of-line format (LF, CRLF, or CR) of the coding system.  */
  int eol_type;

  /* Non-zero means that the current source text is the last block of the
     whole text to be converted.  */
  int last_block;

  /* Non-zero means that characters are being composed currently while
     decoding or encoding.  See macros COMPOSING_XXXX above for the
     meaing of each non-zero value.  */
  int composing;

  /* 0 (left-to-right) or 1 (right-to-left): the direction of the text
     being processed currently.  */
  int direction;

  /* Non-zero means that the current source text is in a buffer which
     enables selective display.  */
  int selective;

  /* Detailed information specific to each type of coding system.  */
  union spec
    {
      struct iso2022_spec iso2022;
      struct ccl_spec ccl;	/* Defined in ccl.h.  */
    } spec;

  /* Backward pointer to the Lisp symbol of the coding system.  */
  Lisp_Object symbol;

  /* Lisp function (symbol) to be called after decoding to do
     additional conversion. */
  Lisp_Object post_read_conversion;

  /* Lisp function (symbol) to be called before encoding to do
     additional conversion. */
  Lisp_Object pre_write_conversion;

  /* Character unification tables to look up, or nil.  */
  Lisp_Object character_unification_table_for_decode;
  Lisp_Object character_unification_table_for_encode;

  /* Carryover yielded by decoding/encoding incomplete source.  No
     coding-system yields more than 7-byte of carryover.  This does
     not include a text which is not processed because of short of
     output buffer.  */
  char carryover[8];

  /* Actual data length in the above array.  */
  int carryover_size;
};

/* Return 1 if coding system CODING never requires any code conversion.  */
#define CODING_REQUIRE_NO_CONVERSION(coding)		\
  (((coding)->type == coding_type_no_conversion		\
    || (coding)->type == coding_type_emacs_mule)	\
   && (coding)->eol_type == CODING_EOL_LF)

/* Return 1 if coding system CODING may not require code conversion.  */
#define CODING_MAY_REQUIRE_NO_CONVERSION(coding)	\
  (((coding)->type == coding_type_no_conversion		\
    || (coding)->type == coding_type_emacs_mule		\
    || (coding)->type == coding_type_undecided)		\
   && ((coding)->eol_type == CODING_EOL_LF		\
       || (coding)->eol_type == CODING_EOL_UNDECIDED))

/* Index for each coding category in `coding_category_table' */
#define CODING_CATEGORY_IDX_EMACS_MULE	0
#define CODING_CATEGORY_IDX_SJIS	1
#define CODING_CATEGORY_IDX_ISO_7	2
#define CODING_CATEGORY_IDX_ISO_8_1	3
#define CODING_CATEGORY_IDX_ISO_8_2	4
#define CODING_CATEGORY_IDX_ISO_7_ELSE	5
#define CODING_CATEGORY_IDX_ISO_8_ELSE	6
#define CODING_CATEGORY_IDX_BIG5	7
#define CODING_CATEGORY_IDX_BINARY	8
#define CODING_CATEGORY_IDX_MAX		9

/* Definitions of flag bits returned by the function
   detect_coding_mask ().  */
#define CODING_CATEGORY_MASK_EMACS_MULE	(1 << CODING_CATEGORY_IDX_EMACS_MULE)
#define CODING_CATEGORY_MASK_SJIS	(1 << CODING_CATEGORY_IDX_SJIS)
#define CODING_CATEGORY_MASK_ISO_7	(1 << CODING_CATEGORY_IDX_ISO_7)
#define CODING_CATEGORY_MASK_ISO_8_1	(1 << CODING_CATEGORY_IDX_ISO_8_1)
#define CODING_CATEGORY_MASK_ISO_8_2	(1 << CODING_CATEGORY_IDX_ISO_8_2)
#define CODING_CATEGORY_MASK_ISO_7_ELSE	(1 << CODING_CATEGORY_IDX_ISO_7_ELSE)
#define CODING_CATEGORY_MASK_ISO_8_ELSE	(1 << CODING_CATEGORY_IDX_ISO_8_ELSE)
#define CODING_CATEGORY_MASK_BIG5	(1 << CODING_CATEGORY_IDX_BIG5)
#define CODING_CATEGORY_MASK_BINARY	(1 << CODING_CATEGORY_IDX_BINARY)

/* This value is returned if detect_coding_mask () find nothing other
   than ASCII characters.  */
#define CODING_CATEGORY_MASK_ANY  	\
  (  CODING_CATEGORY_MASK_EMACS_MULE	\
   | CODING_CATEGORY_MASK_SJIS	  	\
   | CODING_CATEGORY_MASK_ISO_7	  	\
   | CODING_CATEGORY_MASK_ISO_8_1 	\
   | CODING_CATEGORY_MASK_ISO_8_2 	\
   | CODING_CATEGORY_MASK_ISO_7_ELSE	\
   | CODING_CATEGORY_MASK_ISO_8_ELSE	\
   | CODING_CATEGORY_MASK_BIG5)

/* Macros to decode or encode a character of JISX0208 in SJIS.  S1 and
   S2 are the 1st and 2nd position-codes of JISX0208 in SJIS coding
   system.  C1 and C2 are the 1st and 2nd position codes of Emacs'
   internal format.  */

#define DECODE_SJIS(s1, s2, c1, c2)		  	\
  do {						  	\
    if (s2 >= 0x9F)				  	\
      c1 = s1 * 2 - (s1 >= 0xE0 ? 0x160 : 0xE0),  	\
      c2 = s2 - 0x7E;				  	\
    else					  	\
      c1 = s1 * 2 - ((s1 >= 0xE0) ? 0x161 : 0xE1),	\
      c2 = s2 - ((s2 >= 0x7F) ? 0x20 : 0x1F);	  	\
  } while (0)

#define ENCODE_SJIS(c1, c2, s1, s2)			\
  do {							\
    if (c1 & 1)						\
      s1 = c1 / 2 + ((c1 < 0x5F) ? 0x71 : 0xB1),	\
      s2 = c2 + ((c2 >= 0x60) ? 0x20 : 0x1F);		\
    else						\
      s1 = c1 / 2 + ((c1 < 0x5F) ? 0x70 : 0xB0),	\
      s2 = c2 + 0x7E;					\
  } while (0)

/* Extern declarations.  */
extern int decode_coding (), encode_coding ();
extern int decoding_buffer_size (), encoding_buffer_size ();
extern int conversion_buffer_size;
extern char *conversion_buffer, *get_conversion_buffer ();
extern Lisp_Object Fcheck_coding_system ();
extern Lisp_Object Qcoding_system, Qeol_type, Qcoding_category_index;
extern Lisp_Object Qemacs_mule;
extern Lisp_Object Qbuffer_file_coding_system;
extern Lisp_Object Vcoding_category_list;

/* Mnemonic character to indicate each type of end-of-line.  */
extern int eol_mnemonic_unix, eol_mnemonic_dos, eol_mnemonic_mac;
/* Mnemonic character to indicate type of end-of-line is not yet decided.  */
extern int eol_mnemonic_undecided;

/* Table of coding-systems currently assigned to each coding-category.  */
extern Lisp_Object coding_category_table[CODING_CATEGORY_IDX_MAX];
/* Table of names of symbol for each coding-category.  */
extern char *coding_category_name[CODING_CATEGORY_IDX_MAX];

#ifdef emacs
extern Lisp_Object Qfile_coding_system;
extern Lisp_Object Qcall_process, Qcall_process_region, Qprocess_argument;
extern Lisp_Object Qstart_process, Qopen_network_stream;

/* Coding-system for reading files and receiving data from process.  */
extern Lisp_Object Vcoding_system_for_read;
/* Coding-system for writing files and sending data to process.  */
extern Lisp_Object Vcoding_system_for_write;
/* Coding-system actually used in the latest I/O.  */
extern Lisp_Object Vlast_coding_system_used;

/* Coding-system to be used for encoding terminal output.  This
   structure contains information of a coding-system specified by the
   function `set-terminal-coding-system'.  */
extern struct coding_system terminal_coding;

/* Coding system to be used to encode text for terminal display when
   terminal coding system is nil.  */
extern struct coding_system safe_terminal_coding;

/* Coding-system of what is sent from terminal keyboard.  This
   structure contains information of a coding-system specified by the
   function `set-keyboard-coding-system'.  */
extern struct coding_system keyboard_coding;

/* Default coding systems used for process I/O.  */
extern Lisp_Object Vdefault_process_coding_system;

#endif

#endif /* _CODING_H */