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/* Coding system handler (conversion, detection, etc).
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   Copyright (C) 2001-2015 Free Software Foundation, Inc.
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   Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
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     2005, 2006, 2007, 2008, 2009, 2010, 2011
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     National Institute of Advanced Industrial Science and Technology (AIST)
     Registration Number H14PRO021
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   Copyright (C) 2003
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     National Institute of Advanced Industrial Science and Technology (AIST)
     Registration Number H13PRO009
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This file is part of GNU Emacs.

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GNU Emacs is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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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.
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You should have received a copy of the GNU General Public License
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along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
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/*** TABLE OF CONTENTS ***

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  0. General comments
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  1. Preamble
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  2. Emacs' internal format (emacs-utf-8) handlers
  3. UTF-8 handlers
  4. UTF-16 handlers
  5. Charset-base coding systems handlers
  6. emacs-mule (old Emacs' internal format) handlers
  7. ISO2022 handlers
  8. Shift-JIS and BIG5 handlers
  9. CCL handlers
  10. C library functions
  11. Emacs Lisp library functions
  12. Postamble
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*/

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/*** 0. General comments ***
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CODING SYSTEM
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  A coding system is an object for an encoding mechanism that contains
  information about how to convert byte sequences to character
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  sequences and vice versa.  When we say "decode", it means converting
  a byte sequence of a specific coding system into a character
  sequence that is represented by Emacs' internal coding system
  `emacs-utf-8', and when we say "encode", it means converting a
  character sequence of emacs-utf-8 to a byte sequence of a specific
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  coding system.
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  In Emacs Lisp, a coding system is represented by a Lisp symbol.  On
  the C level, a coding system is represented by a vector of attributes
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  stored in the hash table Vcharset_hash_table.  The conversion from
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  coding system symbol to attributes vector is done by looking up
  Vcharset_hash_table by the symbol.
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  Coding systems are classified into the following types depending on
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  the encoding mechanism.  Here's a brief description of the types.
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  o UTF-8

  o UTF-16

  o Charset-base coding system

  A coding system defined by one or more (coded) character sets.
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  Decoding and encoding are done by a code converter defined for each
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  character set.

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  o Old Emacs internal format (emacs-mule)
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  The coding system adopted by old versions of Emacs (20 and 21).
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  o ISO2022-base coding system
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  The most famous coding system for multiple character sets.  X's
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  Compound Text, various EUCs (Extended Unix Code), and coding systems
  used in the Internet communication such as ISO-2022-JP are all
  variants of ISO2022.
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  o SJIS (or Shift-JIS or MS-Kanji-Code)
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  A coding system to encode character sets: ASCII, JISX0201, and
  JISX0208.  Widely used for PC's in Japan.  Details are described in
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  section 8.
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  o BIG5
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  A coding system to encode character sets: ASCII and Big5.  Widely
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  used for Chinese (mainly in Taiwan and Hong Kong).  Details are
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  described in section 8.  In this file, when we write "big5" (all
  lowercase), we mean the coding system, and when we write "Big5"
  (capitalized), we mean the character set.
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  o CCL
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  If a user wants to decode/encode text encoded in a coding system
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  not listed above, he can supply a decoder and an encoder for it in
  CCL (Code Conversion Language) programs.  Emacs executes the CCL
  program while decoding/encoding.
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  o Raw-text
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  A coding system for text containing raw eight-bit data.  Emacs
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  treats each byte of source text as a character (except for
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  end-of-line conversion).
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  o No-conversion

  Like raw text, but don't do end-of-line conversion.
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END-OF-LINE FORMAT
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  How text end-of-line is encoded depends on operating system.  For
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  instance, Unix's format is just one byte of LF (line-feed) code,
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  whereas DOS's format is two-byte sequence of `carriage-return' and
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  `line-feed' codes.  MacOS's format is usually one byte of
  `carriage-return'.
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  Since text character encoding and end-of-line encoding are
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  independent, any coding system described above can take any format
  of end-of-line (except for no-conversion).
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STRUCT CODING_SYSTEM

  Before using a coding system for code conversion (i.e. decoding and
  encoding), we setup a structure of type `struct coding_system'.
  This structure keeps various information about a specific code
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  conversion (e.g. the location of source and destination data).
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*/

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/* COMMON MACROS */


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/*** GENERAL NOTES on `detect_coding_XXX ()' functions ***

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  These functions check if a byte sequence specified as a source in
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  CODING conforms to the format of XXX, and update the members of
  DETECT_INFO.
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  Return true if the byte sequence conforms to XXX.
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  Below is the template of these functions.  */

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#if 0
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static bool
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detect_coding_XXX (struct coding_system *coding,
		   struct coding_detection_info *detect_info)
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{
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  const unsigned char *src = coding->source;
  const unsigned char *src_end = coding->source + coding->src_bytes;
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  bool multibytep = coding->src_multibyte;
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  ptrdiff_t consumed_chars = 0;
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  int found = 0;
  ...;

  while (1)
    {
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      /* Get one byte from the source.  If the source is exhausted, jump
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	 to no_more_source:.  */
      ONE_MORE_BYTE (c);
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      if (! __C_conforms_to_XXX___ (c))
	break;
      if (! __C_strongly_suggests_XXX__ (c))
	found = CATEGORY_MASK_XXX;
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    }
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  /* The byte sequence is invalid for XXX.  */
  detect_info->rejected |= CATEGORY_MASK_XXX;
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  return 0;
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 no_more_source:
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  /* The source exhausted successfully.  */
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  detect_info->found |= found;
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  return 1;
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}
#endif

/*** GENERAL NOTES on `decode_coding_XXX ()' functions ***

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  These functions decode a byte sequence specified as a source by
  CODING.  The resulting multibyte text goes to a place pointed to by
  CODING->charbuf, the length of which should not exceed
  CODING->charbuf_size;
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  These functions set the information of original and decoded texts in
  CODING->consumed, CODING->consumed_char, and CODING->charbuf_used.
  They also set CODING->result to one of CODING_RESULT_XXX indicating
  how the decoding is finished.
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  Below is the template of these functions.  */
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#if 0
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static void
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decode_coding_XXXX (struct coding_system *coding)
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{
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  const unsigned char *src = coding->source + coding->consumed;
  const unsigned char *src_end = coding->source + coding->src_bytes;
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  /* SRC_BASE remembers the start position in source in each loop.
     The loop will be exited when there's not enough source code, or
     when there's no room in CHARBUF for a decoded character.  */
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  const unsigned char *src_base;
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  /* A buffer to produce decoded characters.  */
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  int *charbuf = coding->charbuf + coding->charbuf_used;
  int *charbuf_end = coding->charbuf + coding->charbuf_size;
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  bool multibytep = coding->src_multibyte;
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  while (1)
    {
      src_base = src;
      if (charbuf < charbuf_end)
	/* No more room to produce a decoded character.  */
	break;
      ONE_MORE_BYTE (c);
      /* Decode it. */
    }

 no_more_source:
  if (src_base < src_end
      && coding->mode & CODING_MODE_LAST_BLOCK)
    /* If the source ends by partial bytes to construct a character,
       treat them as eight-bit raw data.  */
    while (src_base < src_end && charbuf < charbuf_end)
      *charbuf++ = *src_base++;
  /* Remember how many bytes and characters we consumed.  If the
     source is multibyte, the bytes and chars are not identical.  */
  coding->consumed = coding->consumed_char = src_base - coding->source;
  /* Remember how many characters we produced.  */
  coding->charbuf_used = charbuf - coding->charbuf;
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}
#endif

/*** GENERAL NOTES on `encode_coding_XXX ()' functions ***

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  These functions encode SRC_BYTES length text at SOURCE of Emacs'
  internal multibyte format by CODING.  The resulting byte sequence
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  goes to a place pointed to by DESTINATION, the length of which
  should not exceed DST_BYTES.
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  These functions set the information of original and encoded texts in
  the members produced, produced_char, consumed, and consumed_char of
  the structure *CODING.  They also set the member result to one of
  CODING_RESULT_XXX indicating how the encoding finished.
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  DST_BYTES zero means that source area and destination area are
  overlapped, which means that we can produce a encoded text until it
  reaches at the head of not-yet-encoded source text.
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  Below is a template of these functions.  */
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#if 0
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static void
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encode_coding_XXX (struct coding_system *coding)
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{
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  bool multibytep = coding->dst_multibyte;
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  int *charbuf = coding->charbuf;
  int *charbuf_end = charbuf->charbuf + coding->charbuf_used;
  unsigned char *dst = coding->destination + coding->produced;
  unsigned char *dst_end = coding->destination + coding->dst_bytes;
  unsigned char *adjusted_dst_end = dst_end - _MAX_BYTES_PRODUCED_IN_LOOP_;
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  ptrdiff_t produced_chars = 0;
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  for (; charbuf < charbuf_end && dst < adjusted_dst_end; charbuf++)
    {
      int c = *charbuf;
      /* Encode C into DST, and increment DST.  */
    }
 label_no_more_destination:
  /* How many chars and bytes we produced.  */
  coding->produced_char += produced_chars;
  coding->produced = dst - coding->destination;
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}
#endif


/*** 1. Preamble ***/

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#include <config.h>
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#include <stdio.h>

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#ifdef HAVE_WCHAR_H
#include <wchar.h>
#endif /* HAVE_WCHAR_H */

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#include "lisp.h"
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#include "character.h"
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#include "buffer.h"
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#include "charset.h"
#include "ccl.h"
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#include "composite.h"
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#include "coding.h"
#include "window.h"
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#include "frame.h"
#include "termhooks.h"
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Lisp_Object Vcoding_system_hash_table;
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/* Format of end-of-line decided by system.  This is Qunix on
   Unix and Mac, Qdos on DOS/Windows.
   This has an effect only for external encoding (i.e. for output to
   file and process), not for in-buffer or Lisp string encoding.  */
static Lisp_Object system_eol_type;

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#ifdef emacs

/* Coding-systems are handed between Emacs Lisp programs and C internal
   routines by the following three variables.  */
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/* Coding system to be used to encode text for terminal display when
   terminal coding system is nil.  */
struct coding_system safe_terminal_coding;

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#endif /* emacs */

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/* Two special coding systems.  */
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static Lisp_Object Vsjis_coding_system;
static Lisp_Object Vbig5_coding_system;
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/* ISO2022 section */

#define CODING_ISO_INITIAL(coding, reg)			\
  (XINT (AREF (AREF (CODING_ID_ATTRS ((coding)->id),	\
		     coding_attr_iso_initial),		\
	       reg)))


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#define CODING_ISO_REQUEST(coding, charset_id)		\
  (((charset_id) <= (coding)->max_charset_id		\
    ? ((coding)->safe_charsets[charset_id] != 255	\
       ? (coding)->safe_charsets[charset_id]		\
       : -1)						\
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    : -1))


#define CODING_ISO_FLAGS(coding)	\
  ((coding)->spec.iso_2022.flags)
#define CODING_ISO_DESIGNATION(coding, reg)	\
  ((coding)->spec.iso_2022.current_designation[reg])
#define CODING_ISO_INVOCATION(coding, plane)	\
  ((coding)->spec.iso_2022.current_invocation[plane])
#define CODING_ISO_SINGLE_SHIFTING(coding)	\
  ((coding)->spec.iso_2022.single_shifting)
#define CODING_ISO_BOL(coding)	\
  ((coding)->spec.iso_2022.bol)
#define CODING_ISO_INVOKED_CHARSET(coding, plane)	\
  CODING_ISO_DESIGNATION ((coding), CODING_ISO_INVOCATION ((coding), (plane)))
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#define CODING_ISO_CMP_STATUS(coding)	\
  (&(coding)->spec.iso_2022.cmp_status)
#define CODING_ISO_EXTSEGMENT_LEN(coding)	\
  ((coding)->spec.iso_2022.ctext_extended_segment_len)
#define CODING_ISO_EMBEDDED_UTF_8(coding)	\
  ((coding)->spec.iso_2022.embedded_utf_8)
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/* Control characters of ISO2022.  */
			/* code */	/* function */
#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-introducer */

/* All code (1-byte) of ISO2022 is classified into one of the
   followings.  */
enum iso_code_class_type
  {
    ISO_control_0,		/* Control codes in the range
				   0x00..0x1F and 0x7F, except for the
				   following 5 codes.  */
    ISO_shift_out,		/* ISO_CODE_SO (0x0E) */
    ISO_shift_in,		/* ISO_CODE_SI (0x0F) */
    ISO_single_shift_2_7,	/* ISO_CODE_SS2_7 (0x19) */
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    ISO_escape,			/* ISO_CODE_ESC (0x1B) */
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    ISO_control_1,		/* Control codes in the range
				   0x80..0x9F, except for the
				   following 3 codes.  */
    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.  */
  };
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/** The macros CODING_ISO_FLAG_XXX defines a flag bit of the
    `iso-flags' attribute of an iso2022 coding system.  */
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/* If set, produce long-form designation sequence (e.g. ESC $ ( A)
   instead of the correct short-form sequence (e.g. ESC $ A).  */
#define CODING_ISO_FLAG_LONG_FORM	0x0001
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/* If set, reset graphic planes and registers at end-of-line to the
   initial state.  */
#define CODING_ISO_FLAG_RESET_AT_EOL	0x0002
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/* If set, reset graphic planes and registers before any control
   characters to the initial state.  */
#define CODING_ISO_FLAG_RESET_AT_CNTL	0x0004
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/* If set, encode by 7-bit environment.  */
#define CODING_ISO_FLAG_SEVEN_BITS	0x0008
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/* If set, use locking-shift function.  */
#define CODING_ISO_FLAG_LOCKING_SHIFT	0x0010
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/* If set, use single-shift function.  Overwrite
   CODING_ISO_FLAG_LOCKING_SHIFT.  */
#define CODING_ISO_FLAG_SINGLE_SHIFT	0x0020
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/* If set, use designation escape sequence.  */
#define CODING_ISO_FLAG_DESIGNATION	0x0040
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/* If set, produce revision number sequence.  */
#define CODING_ISO_FLAG_REVISION	0x0080
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/* If set, produce ISO6429's direction specifying sequence.  */
#define CODING_ISO_FLAG_DIRECTION	0x0100
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/* If set, assume designation states are reset at beginning of line on
   output.  */
#define CODING_ISO_FLAG_INIT_AT_BOL	0x0200
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/* If set, designation sequence should be placed at beginning of line
   on output.  */
#define CODING_ISO_FLAG_DESIGNATE_AT_BOL 0x0400
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/* If set, do not encode unsafe characters on output.  */
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#define CODING_ISO_FLAG_SAFE		0x0800
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/* If set, extra latin codes (128..159) are accepted as a valid code
   on input.  */
#define CODING_ISO_FLAG_LATIN_EXTRA	0x1000
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#define CODING_ISO_FLAG_COMPOSITION	0x2000
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/* #define CODING_ISO_FLAG_EUC_TW_SHIFT	0x4000 */
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#define CODING_ISO_FLAG_USE_ROMAN	0x8000
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#define CODING_ISO_FLAG_USE_OLDJIS	0x10000
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#define CODING_ISO_FLAG_LEVEL_4		0x20000

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#define CODING_ISO_FLAG_FULL_SUPPORT	0x100000
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/* A character to be produced on output if encoding of the original
   character is prohibited by CODING_ISO_FLAG_SAFE.  */
#define CODING_INHIBIT_CHARACTER_SUBSTITUTION  '?'
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/* UTF-8 section */
#define CODING_UTF_8_BOM(coding)	\
  ((coding)->spec.utf_8_bom)
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/* UTF-16 section */
#define CODING_UTF_16_BOM(coding)	\
  ((coding)->spec.utf_16.bom)
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#define CODING_UTF_16_ENDIAN(coding)	\
  ((coding)->spec.utf_16.endian)
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#define CODING_UTF_16_SURROGATE(coding)	\
  ((coding)->spec.utf_16.surrogate)
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/* CCL section */
#define CODING_CCL_DECODER(coding)	\
  AREF (CODING_ID_ATTRS ((coding)->id), coding_attr_ccl_decoder)
#define CODING_CCL_ENCODER(coding)	\
  AREF (CODING_ID_ATTRS ((coding)->id), coding_attr_ccl_encoder)
#define CODING_CCL_VALIDS(coding)					   \
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  (SDATA (AREF (CODING_ID_ATTRS ((coding)->id), coding_attr_ccl_valids)))
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/* Index for each coding category in `coding_categories' */
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enum coding_category
  {
    coding_category_iso_7,
    coding_category_iso_7_tight,
    coding_category_iso_8_1,
    coding_category_iso_8_2,
    coding_category_iso_7_else,
    coding_category_iso_8_else,
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    coding_category_utf_8_auto,
    coding_category_utf_8_nosig,
    coding_category_utf_8_sig,
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    coding_category_utf_16_auto,
    coding_category_utf_16_be,
    coding_category_utf_16_le,
    coding_category_utf_16_be_nosig,
    coding_category_utf_16_le_nosig,
    coding_category_charset,
    coding_category_sjis,
    coding_category_big5,
    coding_category_ccl,
    coding_category_emacs_mule,
    /* All above are targets of code detection.  */
    coding_category_raw_text,
    coding_category_undecided,
    coding_category_max
  };

/* Definitions of flag bits used in detect_coding_XXXX.  */
#define CATEGORY_MASK_ISO_7		(1 << coding_category_iso_7)
#define CATEGORY_MASK_ISO_7_TIGHT	(1 << coding_category_iso_7_tight)
#define CATEGORY_MASK_ISO_8_1		(1 << coding_category_iso_8_1)
#define CATEGORY_MASK_ISO_8_2		(1 << coding_category_iso_8_2)
#define CATEGORY_MASK_ISO_7_ELSE	(1 << coding_category_iso_7_else)
#define CATEGORY_MASK_ISO_8_ELSE	(1 << coding_category_iso_8_else)
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#define CATEGORY_MASK_UTF_8_AUTO	(1 << coding_category_utf_8_auto)
#define CATEGORY_MASK_UTF_8_NOSIG	(1 << coding_category_utf_8_nosig)
#define CATEGORY_MASK_UTF_8_SIG		(1 << coding_category_utf_8_sig)
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#define CATEGORY_MASK_UTF_16_AUTO	(1 << coding_category_utf_16_auto)
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#define CATEGORY_MASK_UTF_16_BE		(1 << coding_category_utf_16_be)
#define CATEGORY_MASK_UTF_16_LE		(1 << coding_category_utf_16_le)
#define CATEGORY_MASK_UTF_16_BE_NOSIG	(1 << coding_category_utf_16_be_nosig)
#define CATEGORY_MASK_UTF_16_LE_NOSIG	(1 << coding_category_utf_16_le_nosig)
#define CATEGORY_MASK_CHARSET		(1 << coding_category_charset)
#define CATEGORY_MASK_SJIS		(1 << coding_category_sjis)
#define CATEGORY_MASK_BIG5		(1 << coding_category_big5)
#define CATEGORY_MASK_CCL		(1 << coding_category_ccl)
#define CATEGORY_MASK_EMACS_MULE	(1 << coding_category_emacs_mule)
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#define CATEGORY_MASK_RAW_TEXT		(1 << coding_category_raw_text)
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/* This value is returned if detect_coding_mask () find nothing other
   than ASCII characters.  */
#define CATEGORY_MASK_ANY		\
  (CATEGORY_MASK_ISO_7			\
   | CATEGORY_MASK_ISO_7_TIGHT		\
   | CATEGORY_MASK_ISO_8_1		\
   | CATEGORY_MASK_ISO_8_2		\
   | CATEGORY_MASK_ISO_7_ELSE		\
   | CATEGORY_MASK_ISO_8_ELSE		\
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   | CATEGORY_MASK_UTF_8_AUTO		\
   | CATEGORY_MASK_UTF_8_NOSIG		\
   | CATEGORY_MASK_UTF_8_SIG		\
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   | CATEGORY_MASK_UTF_16_AUTO		\
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   | CATEGORY_MASK_UTF_16_BE		\
   | CATEGORY_MASK_UTF_16_LE		\
   | CATEGORY_MASK_UTF_16_BE_NOSIG	\
   | CATEGORY_MASK_UTF_16_LE_NOSIG	\
   | CATEGORY_MASK_CHARSET		\
   | CATEGORY_MASK_SJIS			\
   | CATEGORY_MASK_BIG5			\
   | CATEGORY_MASK_CCL			\
   | CATEGORY_MASK_EMACS_MULE)


#define CATEGORY_MASK_ISO_7BIT \
  (CATEGORY_MASK_ISO_7 | CATEGORY_MASK_ISO_7_TIGHT)

#define CATEGORY_MASK_ISO_8BIT \
  (CATEGORY_MASK_ISO_8_1 | CATEGORY_MASK_ISO_8_2)

#define CATEGORY_MASK_ISO_ELSE \
  (CATEGORY_MASK_ISO_7_ELSE | CATEGORY_MASK_ISO_8_ELSE)

#define CATEGORY_MASK_ISO_ESCAPE	\
  (CATEGORY_MASK_ISO_7			\
   | CATEGORY_MASK_ISO_7_TIGHT		\
   | CATEGORY_MASK_ISO_7_ELSE		\
   | CATEGORY_MASK_ISO_8_ELSE)

#define CATEGORY_MASK_ISO	\
  (  CATEGORY_MASK_ISO_7BIT	\
     | CATEGORY_MASK_ISO_8BIT	\
     | CATEGORY_MASK_ISO_ELSE)

#define CATEGORY_MASK_UTF_16		\
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  (CATEGORY_MASK_UTF_16_AUTO		\
   | CATEGORY_MASK_UTF_16_BE		\
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   | CATEGORY_MASK_UTF_16_LE		\
   | CATEGORY_MASK_UTF_16_BE_NOSIG	\
   | CATEGORY_MASK_UTF_16_LE_NOSIG)

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#define CATEGORY_MASK_UTF_8	\
  (CATEGORY_MASK_UTF_8_AUTO	\
   | CATEGORY_MASK_UTF_8_NOSIG	\
   | CATEGORY_MASK_UTF_8_SIG)
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/* Table of coding categories (Lisp symbols).  This variable is for
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   internal use only.  */
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static Lisp_Object Vcoding_category_table;

/* Table of coding-categories ordered by priority.  */
static enum coding_category coding_priorities[coding_category_max];

/* Nth element is a coding context for the coding system bound to the
   Nth coding category.  */
static struct coding_system coding_categories[coding_category_max];

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/* Encode a flag that can be nil, something else, or t as -1, 0, 1.  */

static int
encode_inhibit_flag (Lisp_Object flag)
{
  return NILP (flag) ? -1 : EQ (flag, Qt);
}

/* True if the value of ENCODED_FLAG says a flag should be treated as set.
   1 means yes, -1 means no, 0 means ask the user variable VAR.  */

static bool
inhibit_flag (int encoded_flag, bool var)
{
  return 0 < encoded_flag + var;
}

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#define CODING_GET_INFO(coding, attrs, charset_list)	\
  do {							\
    (attrs) = CODING_ID_ATTRS ((coding)->id);		\
    (charset_list) = CODING_ATTR_CHARSET_LIST (attrs);	\
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  } while (0)
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static void
CHECK_NATNUM_CAR (Lisp_Object x)
{
  Lisp_Object tmp = XCAR (x);
  CHECK_NATNUM (tmp);
  XSETCAR (x, tmp);
}

static void
CHECK_NATNUM_CDR (Lisp_Object x)
{
  Lisp_Object tmp = XCDR (x);
  CHECK_NATNUM (tmp);
  XSETCDR (x, tmp);
}

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/* True if CODING's destination can be grown.  */

static bool
growable_destination (struct coding_system *coding)
{
  return STRINGP (coding->dst_object) || BUFFERP (coding->dst_object);
}

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/* Safely get one byte from the source text pointed by SRC which ends
   at SRC_END, and set C to that byte.  If there are not enough bytes
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   in the source, it jumps to 'no_more_source'.  If MULTIBYTEP,
   and a multibyte character is found at SRC, set C to the
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   negative value of the character code.  The caller should declare
   and set these variables appropriately in advance:
	src, src_end, multibytep */
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#define ONE_MORE_BYTE(c)				\
  do {							\
    if (src == src_end)					\
      {							\
	if (src_base < src)				\
	  record_conversion_result			\
	    (coding, CODING_RESULT_INSUFFICIENT_SRC);	\
	goto no_more_source;				\
      }							\
    c = *src++;						\
    if (multibytep && (c & 0x80))			\
      {							\
	if ((c & 0xFE) == 0xC0)				\
	  c = ((c & 1) << 6) | *src++;			\
	else						\
	  {						\
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	    src--;					\
	    c = - string_char (src, &src, NULL);	\
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	    record_conversion_result			\
	      (coding, CODING_RESULT_INVALID_SRC);	\
	  }						\
      }							\
    consumed_chars++;					\
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  } while (0)

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/* Safely get two bytes from the source text pointed by SRC which ends
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   at SRC_END, and set C1 and C2 to those bytes while skipping the
   heading multibyte characters.  If there are not enough bytes in the
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   source, it jumps to 'no_more_source'.  If MULTIBYTEP and
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   a multibyte character is found for C2, set C2 to the negative value
   of the character code.  The caller should declare and set these
   variables appropriately in advance:
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	src, src_end, multibytep
   It is intended that this macro is used in detect_coding_utf_16.  */

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#define TWO_MORE_BYTES(c1, c2)				\
  do {							\
    do {						\
      if (src == src_end)				\
	goto no_more_source;				\
      c1 = *src++;					\
      if (multibytep && (c1 & 0x80))			\
	{						\
	  if ((c1 & 0xFE) == 0xC0)			\
	    c1 = ((c1 & 1) << 6) | *src++;		\
	  else						\
	    {						\
	      src += BYTES_BY_CHAR_HEAD (c1) - 1;	\
	      c1 = -1;					\
	    }						\
	}						\
    } while (c1 < 0);					\
    if (src == src_end)					\
      goto no_more_source;				\
    c2 = *src++;					\
    if (multibytep && (c2 & 0x80))			\
      {							\
	if ((c2 & 0xFE) == 0xC0)			\
	  c2 = ((c2 & 1) << 6) | *src++;		\
	else						\
	  c2 = -1;					\
      }							\
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  } while (0)

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/* Store a byte C in the place pointed by DST and increment DST to the
   next free point, and increment PRODUCED_CHARS.  The caller should
   assure that C is 0..127, and declare and set the variable `dst'
   appropriately in advance.
*/
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#define EMIT_ONE_ASCII_BYTE(c)	\
  do {				\
    produced_chars++;		\
    *dst++ = (c);		\
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  } while (0)
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/* Like EMIT_ONE_ASCII_BYTE but store two bytes; C1 and C2.  */
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#define EMIT_TWO_ASCII_BYTES(c1, c2)	\
  do {					\
    produced_chars += 2;		\
    *dst++ = (c1), *dst++ = (c2);	\
  } while (0)
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/* Store a byte C in the place pointed by DST and increment DST to the
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   next free point, and increment PRODUCED_CHARS.  If MULTIBYTEP,
   store in an appropriate multibyte form.  The caller should
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   declare and set the variables `dst' and `multibytep' appropriately
   in advance.  */

#define EMIT_ONE_BYTE(c)		\
  do {					\
    produced_chars++;			\
    if (multibytep)			\
      {					\
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	unsigned ch = (c);		\
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	if (ch >= 0x80)			\
	  ch = BYTE8_TO_CHAR (ch);	\
	CHAR_STRING_ADVANCE (ch, dst);	\
      }					\
    else				\
      *dst++ = (c);			\
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  } while (0)


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/* Like EMIT_ONE_BYTE, but emit two bytes; C1 and C2.  */
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#define EMIT_TWO_BYTES(c1, c2)		\
  do {					\
    produced_chars += 2;		\
    if (multibytep)			\
      {					\
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	unsigned ch;			\
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					\
	ch = (c1);			\
	if (ch >= 0x80)			\
	  ch = BYTE8_TO_CHAR (ch);	\
	CHAR_STRING_ADVANCE (ch, dst);	\
	ch = (c2);			\
	if (ch >= 0x80)			\
	  ch = BYTE8_TO_CHAR (ch);	\
	CHAR_STRING_ADVANCE (ch, dst);	\
      }					\
    else				\
      {					\
	*dst++ = (c1);			\
	*dst++ = (c2);			\
      }					\
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  } while (0)


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#define EMIT_THREE_BYTES(c1, c2, c3)	\
  do {					\
    EMIT_ONE_BYTE (c1);			\
    EMIT_TWO_BYTES (c2, c3);		\
  } while (0)
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#define EMIT_FOUR_BYTES(c1, c2, c3, c4)		\
  do {						\
    EMIT_TWO_BYTES (c1, c2);			\
    EMIT_TWO_BYTES (c3, c4);			\
  } while (0)
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static void
record_conversion_result (struct coding_system *coding,
			  enum coding_result_code result)
{
  coding->result = result;
  switch (result)
    {
    case CODING_RESULT_INSUFFICIENT_SRC:
      Vlast_code_conversion_error = Qinsufficient_source;
      break;
    case CODING_RESULT_INVALID_SRC:
      Vlast_code_conversion_error = Qinvalid_source;
      break;
    case CODING_RESULT_INTERRUPT:
      Vlast_code_conversion_error = Qinterrupted;
      break;
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    case CODING_RESULT_INSUFFICIENT_DST:
      /* Don't record this error in Vlast_code_conversion_error
	 because it happens just temporarily and is resolved when the
	 whole conversion is finished.  */
      break;
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    case CODING_RESULT_SUCCESS:
      break;
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    default:
      Vlast_code_conversion_error = intern ("Unknown error");
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    }
}

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/* These wrapper macros are used to preserve validity of pointers into
   buffer text across calls to decode_char, encode_char, etc, which
   could cause relocation of buffers if it loads a charset map,
   because loading a charset map allocates large structures.  */

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#define CODING_DECODE_CHAR(coding, src, src_base, src_end, charset, code, c) \
  do {									     \
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    ptrdiff_t offset;							     \
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									     \
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    charset_map_loaded = 0;						     \
    c = DECODE_CHAR (charset, code);					     \
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    if (charset_map_loaded						     \
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	&& (offset = coding_change_source (coding)))			     \
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      {									     \
	src += offset;							     \
	src_base += offset;						     \
	src_end += offset;						     \
      }									     \
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  } while (0)

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#define CODING_ENCODE_CHAR(coding, dst, dst_end, charset, c, code)	\
  do {									\
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    ptrdiff_t offset;							\
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									\
    charset_map_loaded = 0;						\
    code = ENCODE_CHAR (charset, c);					\
    if (charset_map_loaded						\
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	&& (offset = coding_change_destination (coding)))		\
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      {									\
	dst += offset;							\
	dst_end += offset;						\
      }									\
  } while (0)

#define CODING_CHAR_CHARSET(coding, dst, dst_end, c, charset_list, code_return, charset) \
  do {									\
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    ptrdiff_t offset;							\
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									\
    charset_map_loaded = 0;						\
    charset = char_charset (c, charset_list, code_return);		\
    if (charset_map_loaded						\
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	&& (offset = coding_change_destination (coding)))		\
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      {									\
	dst += offset;							\
	dst_end += offset;						\
      }									\
  } while (0)

#define CODING_CHAR_CHARSET_P(coding, dst, dst_end, c, charset, result)	\
  do {									\
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    ptrdiff_t offset;							\
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									\
    charset_map_loaded = 0;						\
    result = CHAR_CHARSET_P (c, charset);				\
    if (charset_map_loaded						\
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	&& (offset = coding_change_destination (coding)))		\
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      {									\
	dst += offset;							\
	dst_end += offset;						\
      }									\
  } while (0)

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/* If there are at least BYTES length of room at dst, allocate memory
   for coding->destination and update dst and dst_end.  We don't have
   to take care of coding->source which will be relocated.  It is
   handled by calling coding_set_source in encode_coding.  */

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#define ASSURE_DESTINATION(bytes)				\
  do {								\
    if (dst + (bytes) >= dst_end)				\
      {								\
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	ptrdiff_t more_bytes = charbuf_end - charbuf + (bytes);	\
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								\
	dst = alloc_destination (coding, more_bytes, dst);	\
	dst_end = coding->destination + coding->dst_bytes;	\
      }								\
  } while (0)
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/* Store multibyte form of the character C in P, and advance P to the
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   end of the multibyte form.  This used to be like CHAR_STRING_ADVANCE
   without ever calling MAYBE_UNIFY_CHAR, but nowadays we don't call
   MAYBE_UNIFY_CHAR in CHAR_STRING_ADVANCE.  */
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#define CHAR_STRING_ADVANCE_NO_UNIFY(c, p)  CHAR_STRING_ADVANCE(c, p)
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/* Return the character code of character whose multibyte form is at
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   P, and advance P to the end of the multibyte form.  This used to be
   like STRING_CHAR_ADVANCE without ever calling MAYBE_UNIFY_CHAR, but
   nowadays STRING_CHAR_ADVANCE doesn't call MAYBE_UNIFY_CHAR.  */
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#define STRING_CHAR_ADVANCE_NO_UNIFY(p) STRING_CHAR_ADVANCE(p)
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/* Set coding->source from coding->src_object.  */
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static void
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coding_set_source (struct coding_system *coding)
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{
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  if (BUFFERP (coding->src_object))
    {
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      struct buffer *buf = XBUFFER (coding->src_object);
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      if (coding->src_pos < 0)
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	coding->source = BUF_GAP_END_ADDR (buf) + coding->src_pos_byte;
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      else
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	coding->source = BUF_BYTE_ADDRESS (buf, coding->src_pos_byte);
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    }
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  else if (STRINGP (coding->src_object))
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    {
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      coding->source = SDATA (coding->src_object) + coding->src_pos_byte;
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    }
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  else
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    {
      /* Otherwise, the source is C string and is never relocated
	 automatically.  Thus we don't have to update anything.  */
    }
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}
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/* Set coding->source from coding->src_object, and return how many
   bytes coding->source was changed.  */
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static ptrdiff_t
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coding_change_source (struct coding_system *coding)
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{
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  const unsigned char *orig = coding->source;
  coding_set_source (coding);
  return coding->source - orig;
}

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/* Set coding->destination from coding->dst_object.  */

static void
coding_set_destination (struct coding_system *coding)
{
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  if (BUFFERP (coding->dst_object))
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    {
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      if (BUFFERP (coding->src_object) && coding->src_pos < 0)
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	{
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	  coding->destination = BEG_ADDR + coding->dst_pos_byte - BEG_BYTE;
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	  coding->dst_bytes = (GAP_END_ADDR
			       - (coding->src_bytes - coding->consumed)
			       - coding->destination);
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	}
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      else
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	{
	  /* We are sure that coding->dst_pos_byte is before the gap
	     of the buffer. */
	  coding->destination = (BUF_BEG_ADDR (XBUFFER (coding->dst_object))
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				 + coding->dst_pos_byte - BEG_BYTE);
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	  coding->dst_bytes = (BUF_GAP_END_ADDR (XBUFFER (coding->dst_object))
			       - coding->destination);
	}
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    }
  else
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    {
      /* Otherwise, the destination is C string and is never relocated
	 automatically.  Thus we don't have to update anything.  */
    }
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}


/* Set coding->destination from coding->dst_object, and return how
   many bytes coding->destination was changed.  */

static ptrdiff_t
coding_change_destination (struct coding_system *coding)
{
  const unsigned char *orig = coding->destination;
  coding_set_destination (coding);
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  return coding->destination - orig;
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}


static void
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coding_alloc_by_realloc (struct coding_system *coding, ptrdiff_t bytes)
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{
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  if (STRING_BYTES_BOUND - coding->dst_bytes < bytes)
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    string_overflow ();
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  coding->destination = xrealloc (coding->destination,
				  coding->dst_bytes + bytes);
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  coding->dst_bytes += bytes;
}

static void
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coding_alloc_by_making_gap (struct coding_system *coding,
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			    ptrdiff_t gap_head_used, ptrdiff_t bytes)
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{
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  if (EQ (coding->src_object, coding->dst_object))
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    {
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      /* The gap may contain the produced data at the head and not-yet
	 consumed data at the tail.  To preserve those data, we at
	 first make the gap size to zero, then increase the gap
	 size.  */
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      ptrdiff_t add = GAP_SIZE;
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      GPT += gap_head_used, GPT_BYTE += gap_head_used;
      GAP_SIZE = 0; ZV += add; Z += add; ZV_BYTE += add; Z_BYTE += add;
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      make_gap (bytes);
      GAP_SIZE += add; ZV -= add; Z -= add; ZV_BYTE -= add; Z_BYTE -= add;
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      GPT -= gap_head_used, GPT_BYTE -= gap_head_used;
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    }
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  else
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    make_gap_1 (XBUFFER (coding->dst_object), bytes);
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}
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static unsigned char *
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alloc_destination (struct coding_system *coding, ptrdiff_t nbytes,
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		   unsigned char *dst)
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{
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  ptrdiff_t offset = dst - coding->destination;
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  if (BUFFERP (coding->dst_object))
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    {
      struct buffer *buf = XBUFFER (coding->dst_object);

      coding_alloc_by_making_gap (coding, dst - BUF_GPT_ADDR (buf), nbytes);
    }
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  else
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    coding_alloc_by_realloc (coding, nbytes);
  coding_set_destination (coding);
  dst = coding->destination + offset;
  return dst;
}
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