coding.c 124 KB
Newer Older
Karl Heuer's avatar
Karl Heuer committed
1
/* Coding system handler (conversion, detection, and etc).
2 3
   Copyright (C) 1995, 1997 Electrotechnical Laboratory, JAPAN.
   Licensed to the Free Software Foundation.
Karl Heuer's avatar
Karl Heuer committed
4

Karl Heuer's avatar
Karl Heuer committed
5 6 7 8 9 10
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.
Karl Heuer's avatar
Karl Heuer committed
11

Karl Heuer's avatar
Karl Heuer committed
12 13 14 15
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.
Karl Heuer's avatar
Karl Heuer committed
16

Karl Heuer's avatar
Karl Heuer committed
17 18 19 20
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.  */
Karl Heuer's avatar
Karl Heuer committed
21 22 23 24

/*** TABLE OF CONTENTS ***

  1. Preamble
Kenichi Handa's avatar
Kenichi Handa committed
25
  2. Emacs' internal format (emacs-mule) handlers
Karl Heuer's avatar
Karl Heuer committed
26 27 28 29 30 31 32 33 34 35 36 37 38 39
  3. ISO2022 handlers
  4. Shift-JIS and BIG5 handlers
  5. End-of-line handlers
  6. C library functions
  7. Emacs Lisp library functions
  8. Post-amble

*/

/*** GENERAL NOTE on CODING SYSTEM ***

  Coding system is an encoding mechanism of one or more character
  sets.  Here's a list of coding systems which Emacs can handle.  When
  we say "decode", it means converting some other coding system to
Kenichi Handa's avatar
Kenichi Handa committed
40 41 42
  Emacs' internal format (emacs-internal), and when we say "encode",
  it means converting the coding system emacs-mule to some other
  coding system.
Karl Heuer's avatar
Karl Heuer committed
43

Kenichi Handa's avatar
Kenichi Handa committed
44
  0. Emacs' internal format (emacs-mule)
Karl Heuer's avatar
Karl Heuer committed
45 46

  Emacs itself holds a multi-lingual character in a buffer and a string
Richard M. Stallman's avatar
Richard M. Stallman committed
47
  in a special format.  Details are described in section 2.
Karl Heuer's avatar
Karl Heuer committed
48 49 50 51

  1. ISO2022

  The most famous coding system for multiple character sets.  X's
Richard M. Stallman's avatar
Richard M. Stallman committed
52 53 54
  Compound Text, various EUCs (Extended Unix Code), and coding
  systems used in Internet communication such as ISO-2022-JP are
  all variants of ISO2022.  Details are described in section 3.
Karl Heuer's avatar
Karl Heuer committed
55 56 57 58 59

  2. SJIS (or Shift-JIS or MS-Kanji-Code)
   
  A coding system to encode character sets: ASCII, JISX0201, and
  JISX0208.  Widely used for PC's in Japan.  Details are described in
Richard M. Stallman's avatar
Richard M. Stallman committed
60
  section 4.
Karl Heuer's avatar
Karl Heuer committed
61 62 63 64 65

  3. BIG5

  A coding system to encode character sets: ASCII and Big5.  Widely
  used by Chinese (mainly in Taiwan and Hong Kong).  Details are
Richard M. Stallman's avatar
Richard M. Stallman committed
66 67 68
  described in section 4.  In this file, when we write "BIG5"
  (all uppercase), we mean the coding system, and when we write
  "Big5" (capitalized), we mean the character set.
Karl Heuer's avatar
Karl Heuer committed
69

Richard M. Stallman's avatar
Richard M. Stallman committed
70
  4. Other
Karl Heuer's avatar
Karl Heuer committed
71

Richard M. Stallman's avatar
Richard M. Stallman committed
72
  If a user wants to read/write a text encoded in a coding system not
Karl Heuer's avatar
Karl Heuer committed
73 74 75 76
  listed above, he can supply a decoder and an encoder for it in CCL
  (Code Conversion Language) programs.  Emacs executes the CCL program
  while reading/writing.

Richard M. Stallman's avatar
Richard M. Stallman committed
77
  Emacs represents a coding-system by a Lisp symbol that has a property
Karl Heuer's avatar
Karl Heuer committed
78 79
  `coding-system'.  But, before actually using the coding-system, the
  information about it is set in a structure of type `struct
Richard M. Stallman's avatar
Richard M. Stallman committed
80
  coding_system' for rapid processing.  See section 6 for more details.
Karl Heuer's avatar
Karl Heuer committed
81 82 83 84 85 86 87

*/

/*** GENERAL NOTES on END-OF-LINE FORMAT ***

  How end-of-line of a text is encoded depends on a system.  For
  instance, Unix's format is just one byte of `line-feed' code,
Richard M. Stallman's avatar
Richard M. Stallman committed
88
  whereas DOS's format is two-byte sequence of `carriage-return' and
Karl Heuer's avatar
Karl Heuer committed
89 90
  `line-feed' codes.  MacOS's format is one byte of `carriage-return'.

Richard M. Stallman's avatar
Richard M. Stallman committed
91 92
  Since text characters encoding and end-of-line encoding are
  independent, any coding system described above can take
Karl Heuer's avatar
Karl Heuer committed
93
  any format of end-of-line.  So, Emacs has information of format of
Richard M. Stallman's avatar
Richard M. Stallman committed
94
  end-of-line in each coding-system.  See section 6 for more details.
Karl Heuer's avatar
Karl Heuer committed
95 96 97 98 99 100 101 102 103 104 105 106

*/

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

  These functions check if a text between SRC and SRC_END is encoded
  in the coding system category XXX.  Each returns an integer value in
  which appropriate flag bits for the category XXX is set.  The flag
  bits are defined in macros CODING_CATEGORY_MASK_XXX.  Below is the
  template of these functions.  */
#if 0
int
Kenichi Handa's avatar
Kenichi Handa committed
107
detect_coding_emacs_mule (src, src_end)
Karl Heuer's avatar
Karl Heuer committed
108 109 110 111 112 113 114 115 116
     unsigned char *src, *src_end;
{
  ...
}
#endif

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

  These functions decode SRC_BYTES length text at SOURCE encoded in
Kenichi Handa's avatar
Kenichi Handa committed
117
  CODING to Emacs' internal format (emacs-mule).  The resulting text
Richard M. Stallman's avatar
Richard M. Stallman committed
118 119 120 121
  goes to a place pointed to by DESTINATION, the length of which should
  not exceed DST_BYTES.  The number of bytes actually processed is
  returned as *CONSUMED.  The return value is the length of the decoded
  text.  Below is a template of these functions.  */
Karl Heuer's avatar
Karl Heuer committed
122 123 124 125 126 127 128 129 130 131 132 133 134
#if 0
decode_coding_XXX (coding, source, destination, src_bytes, dst_bytes, consumed)
     struct coding_system *coding;
     unsigned char *source, *destination;
     int src_bytes, dst_bytes;
     int *consumed;
{
  ...
}
#endif

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

Kenichi Handa's avatar
Kenichi Handa committed
135 136
  These functions encode SRC_BYTES length text at SOURCE of Emacs'
  internal format (emacs-mule) to CODING.  The resulting text goes to
Richard M. Stallman's avatar
Richard M. Stallman committed
137 138 139 140
  a place pointed to by DESTINATION, the length of which should not
  exceed DST_BYTES.  The number of bytes actually processed is
  returned as *CONSUMED.  The return value is the length of the
  encoded text.  Below is a template of these functions.  */
Karl Heuer's avatar
Karl Heuer committed
141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200
#if 0
encode_coding_XXX (coding, source, destination, src_bytes, dst_bytes, consumed)
     struct coding_system *coding;
     unsigned char *source, *destination;
     int src_bytes, dst_bytes;
     int *consumed;
{
  ...
}
#endif

/*** COMMONLY USED MACROS ***/

/* The following three macros ONE_MORE_BYTE, TWO_MORE_BYTES, and
   THREE_MORE_BYTES safely get one, two, and three bytes from the
   source text respectively.  If there are not enough bytes in the
   source, they jump to `label_end_of_loop'.  The caller should set
   variables `src' and `src_end' to appropriate areas in advance.  */

#define ONE_MORE_BYTE(c1)   	\
  do {			     	\
    if (src < src_end)	     	\
      c1 = *src++;	     	\
    else		     	\
      goto label_end_of_loop;	\
  } while (0)

#define TWO_MORE_BYTES(c1, c2) 	\
  do {			       	\
    if (src + 1 < src_end)     	\
      c1 = *src++, c2 = *src++;	\
    else		       	\
      goto label_end_of_loop;  	\
  } while (0)

#define THREE_MORE_BYTES(c1, c2, c3)	    	\
  do {					    	\
    if (src + 2 < src_end)		    	\
      c1 = *src++, c2 = *src++, c3 = *src++;	\
    else				    	\
      goto label_end_of_loop;		    	\
  } while (0)

/* The following three macros DECODE_CHARACTER_ASCII,
   DECODE_CHARACTER_DIMENSION1, and DECODE_CHARACTER_DIMENSION2 put
   the multi-byte form of a character of each class at the place
   pointed by `dst'.  The caller should set the variable `dst' to
   point to an appropriate area and the variable `coding' to point to
   the coding-system of the currently decoding text in advance.  */

/* Decode one ASCII character C.  */

#define DECODE_CHARACTER_ASCII(c)				\
  do {								\
    if (COMPOSING_P (coding->composing))			\
      *dst++ = 0xA0, *dst++ = (c) | 0x80;			\
    else							\
      *dst++ = (c);						\
  } while (0)

Richard M. Stallman's avatar
Richard M. Stallman committed
201
/* Decode one DIMENSION1 character whose charset is CHARSET and whose
Karl Heuer's avatar
Karl Heuer committed
202 203 204 205 206 207 208 209 210 211 212 213 214 215
   position-code is C.  */

#define DECODE_CHARACTER_DIMENSION1(charset, c)				\
  do {									\
    unsigned char leading_code = CHARSET_LEADING_CODE_BASE (charset);	\
    if (COMPOSING_P (coding->composing))				\
      *dst++ = leading_code + 0x20;					\
    else								\
      *dst++ = leading_code;						\
    if (leading_code = CHARSET_LEADING_CODE_EXT (charset))		\
      *dst++ = leading_code;						\
    *dst++ = (c) | 0x80;						\
  } while (0)

Richard M. Stallman's avatar
Richard M. Stallman committed
216
/* Decode one DIMENSION2 character whose charset is CHARSET and whose
Karl Heuer's avatar
Karl Heuer committed
217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260
   position-codes are C1 and C2.  */

#define DECODE_CHARACTER_DIMENSION2(charset, c1, c2)	\
  do {							\
    DECODE_CHARACTER_DIMENSION1 (charset, c1);		\
    *dst++ = (c2) | 0x80;				\
  } while (0)


/*** 1. Preamble ***/

#include <stdio.h>

#ifdef emacs

#include <config.h>
#include "lisp.h"
#include "buffer.h"
#include "charset.h"
#include "ccl.h"
#include "coding.h"
#include "window.h"

#else  /* not emacs */

#include "mulelib.h"

#endif /* not emacs */

Lisp_Object Qcoding_system, Qeol_type;
Lisp_Object Qbuffer_file_coding_system;
Lisp_Object Qpost_read_conversion, Qpre_write_conversion;

extern Lisp_Object Qinsert_file_contents, Qwrite_region;
Lisp_Object Qcall_process, Qcall_process_region, Qprocess_argument;
Lisp_Object Qstart_process, Qopen_network_stream;
Lisp_Object Qtarget_idx;

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

261 262 263 264
/* Format of end-of-line decided by system.  This is CODING_EOL_LF on
   Unix, CODING_EOL_CRLF on DOS/Windows, and CODING_EOL_CR on Mac.  */
int system_eol_type;

Karl Heuer's avatar
Karl Heuer committed
265 266
#ifdef emacs

267
Lisp_Object Qcoding_system_spec, Qcoding_system_p, Qcoding_system_error;
Karl Heuer's avatar
Karl Heuer committed
268

269 270 271
/* Coding system emacs-mule is for converting only end-of-line format.  */
Lisp_Object Qemacs_mule;

Karl Heuer's avatar
Karl Heuer committed
272 273 274 275 276 277 278 279 280
/* Coding-systems are handed between Emacs Lisp programs and C internal
   routines by the following three variables.  */
/* Coding-system for reading files and receiving data from process.  */
Lisp_Object Vcoding_system_for_read;
/* Coding-system for writing files and sending data to process.  */
Lisp_Object Vcoding_system_for_write;
/* Coding-system actually used in the latest I/O.  */
Lisp_Object Vlast_coding_system_used;

281 282 283
/* Flag to inhibit code conversion of end-of-line format.  */
int inhibit_eol_conversion;

Karl Heuer's avatar
Karl Heuer committed
284 285 286 287 288 289
/* Coding-system of what terminal accept for displaying.  */
struct coding_system terminal_coding;

/* Coding-system of what is sent from terminal keyboard.  */
struct coding_system keyboard_coding;

290 291 292
Lisp_Object Vfile_coding_system_alist;
Lisp_Object Vprocess_coding_system_alist;
Lisp_Object Vnetwork_coding_system_alist;
Karl Heuer's avatar
Karl Heuer committed
293 294 295 296 297 298 299 300 301 302 303 304 305

#endif /* emacs */

Lisp_Object Qcoding_category_index;

/* List of symbols `coding-category-xxx' ordered by priority.  */
Lisp_Object Vcoding_category_list;

/* Table of coding-systems currently assigned to each coding-category.  */
Lisp_Object coding_category_table[CODING_CATEGORY_IDX_MAX];

/* Table of names of symbol for each coding-category.  */
char *coding_category_name[CODING_CATEGORY_IDX_MAX] = {
Kenichi Handa's avatar
Kenichi Handa committed
306
  "coding-category-emacs-mule",
Karl Heuer's avatar
Karl Heuer committed
307 308 309 310
  "coding-category-sjis",
  "coding-category-iso-7",
  "coding-category-iso-8-1",
  "coding-category-iso-8-2",
311 312
  "coding-category-iso-7-else",
  "coding-category-iso-8-else",
Karl Heuer's avatar
Karl Heuer committed
313 314 315 316
  "coding-category-big5",
  "coding-category-binary"
};

317 318 319
/* Flag to tell if we look up unification table on character code
   conversion.  */
Lisp_Object Venable_character_unification;
320 321 322 323
/* Standard unification table to look up on decoding (reading).  */
Lisp_Object Vstandard_character_unification_table_for_decode;
/* Standard unification table to look up on encoding (writing).  */
Lisp_Object Vstandard_character_unification_table_for_encode;
324 325

Lisp_Object Qcharacter_unification_table;
326 327
Lisp_Object Qcharacter_unification_table_for_decode;
Lisp_Object Qcharacter_unification_table_for_encode;
Karl Heuer's avatar
Karl Heuer committed
328 329 330 331

/* Alist of charsets vs revision number.  */
Lisp_Object Vcharset_revision_alist;

332 333 334
/* Default coding systems used for process I/O.  */
Lisp_Object Vdefault_process_coding_system;

Karl Heuer's avatar
Karl Heuer committed
335

Kenichi Handa's avatar
Kenichi Handa committed
336
/*** 2. Emacs internal format (emacs-mule) handlers ***/
Karl Heuer's avatar
Karl Heuer committed
337 338

/* Emacs' internal format for encoding multiple character sets is a
Richard M. Stallman's avatar
Richard M. Stallman committed
339 340 341 342 343 344 345 346 347 348 349 350 351
   kind of multi-byte encoding, i.e. characters are encoded by
   variable-length sequences of one-byte codes.  ASCII characters
   and control characters (e.g. `tab', `newline') are represented by
   one-byte sequences which are their ASCII codes, in the range 0x00
   through 0x7F.  The other characters are represented by a sequence
   of `base leading-code', optional `extended leading-code', and one
   or two `position-code's.  The length of the sequence is determined
   by the base leading-code.  Leading-code takes the range 0x80
   through 0x9F, whereas extended leading-code and position-code take
   the range 0xA0 through 0xFF.  See `charset.h' for more details
   about leading-code and position-code.

   There's one exception to this rule.  Special leading-code
Karl Heuer's avatar
Karl Heuer committed
352 353 354 355
   `leading-code-composition' denotes that the following several
   characters should be composed into one character.  Leading-codes of
   components (except for ASCII) are added 0x20.  An ASCII character
   component is represented by a 2-byte sequence of `0xA0' and
Richard M. Stallman's avatar
Richard M. Stallman committed
356 357
   `ASCII-code + 0x80'.  See also the comments in `charset.h' for the
   details of composite character.  Hence, we can summarize the code
Karl Heuer's avatar
Karl Heuer committed
358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382
   range as follows:

   --- CODE RANGE of Emacs' internal format ---
   (character set)	(range)
   ASCII		0x00 .. 0x7F
   ELSE (1st byte)	0x80 .. 0x9F
	(rest bytes)	0xA0 .. 0xFF
   ---------------------------------------------

  */

enum emacs_code_class_type emacs_code_class[256];

/* Go to the next statement only if *SRC is accessible and the code is
   greater than 0xA0.  */
#define CHECK_CODE_RANGE_A0_FF 	\
  do {			       	\
    if (src >= src_end)	       	\
      goto label_end_of_switch;	\
    else if (*src++ < 0xA0)    	\
      return 0;		       	\
  } while (0)

/* See the above "GENERAL NOTES on `detect_coding_XXX ()' functions".
   Check if a text is encoded in Emacs' internal format.  If it is,
Kenichi Handa's avatar
Kenichi Handa committed
383
   return CODING_CATEGORY_MASK_EMASC_MULE, else return 0.  */
Karl Heuer's avatar
Karl Heuer committed
384 385

int
Kenichi Handa's avatar
Kenichi Handa committed
386
detect_coding_emacs_mule (src, src_end)
Karl Heuer's avatar
Karl Heuer committed
387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441
     unsigned char *src, *src_end;
{
  unsigned char c;
  int composing = 0;

  while (src < src_end)
    {
      c = *src++;

      if (composing)
	{
	  if (c < 0xA0)
	    composing = 0;
	  else
	    c -= 0x20;
	}

      switch (emacs_code_class[c])
	{
	case EMACS_ascii_code:
	case EMACS_linefeed_code:
	  break;

	case EMACS_control_code:
	  if (c == ISO_CODE_ESC || c == ISO_CODE_SI || c == ISO_CODE_SO)
	    return 0;
	  break;

	case EMACS_invalid_code:
	  return 0;

	case EMACS_leading_code_composition: /* c == 0x80 */
	  if (composing)
	    CHECK_CODE_RANGE_A0_FF;
	  else
	    composing = 1;
	  break;

	case EMACS_leading_code_4:
	  CHECK_CODE_RANGE_A0_FF;
	  /* fall down to check it two more times ...  */

	case EMACS_leading_code_3:
	  CHECK_CODE_RANGE_A0_FF;
	  /* fall down to check it one more time ...  */

	case EMACS_leading_code_2:
	  CHECK_CODE_RANGE_A0_FF;
	  break;

	default:
	label_end_of_switch:
	  break;
	}
    }
Kenichi Handa's avatar
Kenichi Handa committed
442
  return CODING_CATEGORY_MASK_EMACS_MULE;
Karl Heuer's avatar
Karl Heuer committed
443 444 445 446 447 448
}


/*** 3. ISO2022 handlers ***/

/* The following note describes the coding system ISO2022 briefly.
Richard M. Stallman's avatar
Richard M. Stallman committed
449 450
   Since the intention of this note is to help in understanding of
   the programs in this file, some parts are NOT ACCURATE or OVERLY
Karl Heuer's avatar
Karl Heuer committed
451 452 453 454
   SIMPLIFIED.  For the thorough understanding, please refer to the
   original document of ISO2022.

   ISO2022 provides many mechanisms to encode several character sets
Richard M. Stallman's avatar
Richard M. Stallman committed
455
   in 7-bit and 8-bit environment.  If one chooses 7-bite environment,
Karl Heuer's avatar
Karl Heuer committed
456
   all text is encoded by codes of less than 128.  This may make the
Richard M. Stallman's avatar
Richard M. Stallman committed
457 458
   encoded text a little bit longer, but the text gets more stability
   to pass through several gateways (some of them strip off the MSB).
Karl Heuer's avatar
Karl Heuer committed
459

Richard M. Stallman's avatar
Richard M. Stallman committed
460
   There are two kinds of character set: control character set and
Karl Heuer's avatar
Karl Heuer committed
461 462
   graphic character set.  The former contains control characters such
   as `newline' and `escape' to provide control functions (control
Richard M. Stallman's avatar
Richard M. Stallman committed
463
   functions are provided also by escape sequences).  The latter
Karl Heuer's avatar
Karl Heuer committed
464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566
   contains graphic characters such as ' A' and '-'.  Emacs recognizes
   two control character sets and many graphic character sets.

   Graphic character sets are classified into one of the following
   four classes, DIMENSION1_CHARS94, DIMENSION1_CHARS96,
   DIMENSION2_CHARS94, DIMENSION2_CHARS96 according to the number of
   bytes (DIMENSION) and the number of characters in one dimension
   (CHARS) of the set.  In addition, each character set is assigned an
   identification tag (called "final character" and denoted as <F>
   here after) which is unique in each class.  <F> of each character
   set is decided by ECMA(*) when it is registered in ISO.  Code range
   of <F> is 0x30..0x7F (0x30..0x3F are for private use only).

   Note (*): ECMA = European Computer Manufacturers Association

   Here are examples of graphic character set [NAME(<F>)]:
	o DIMENSION1_CHARS94 -- ASCII('B'), right-half-of-JISX0201('I'), ...
	o DIMENSION1_CHARS96 -- right-half-of-ISO8859-1('A'), ...
	o DIMENSION2_CHARS94 -- GB2312('A'), JISX0208('B'), ...
	o DIMENSION2_CHARS96 -- none for the moment

   A code area (1byte=8bits) is divided into 4 areas, C0, GL, C1, and GR.
	C0 [0x00..0x1F] -- control character plane 0
	GL [0x20..0x7F] -- graphic character plane 0
	C1 [0x80..0x9F] -- control character plane 1
	GR [0xA0..0xFF] -- graphic character plane 1

   A control character set is directly designated and invoked to C0 or
   C1 by an escape sequence.  The most common case is that ISO646's
   control character set is designated/invoked to C0 and ISO6429's
   control character set is designated/invoked to C1, and usually
   these designations/invocations are omitted in a coded text.  With
   7-bit environment, only C0 can be used, and a control character for
   C1 is encoded by an appropriate escape sequence to fit in the
   environment.  All control characters for C1 are defined the
   corresponding escape sequences.

   A graphic character set is at first designated to one of four
   graphic registers (G0 through G3), then these graphic registers are
   invoked to GL or GR.  These designations and invocations can be
   done independently.  The most common case is that G0 is invoked to
   GL, G1 is invoked to GR, and ASCII is designated to G0, and usually
   these invocations and designations are omitted in a coded text.
   With 7-bit environment, only GL can be used.

   When a graphic character set of CHARS94 is invoked to GL, code 0x20
   and 0x7F of GL area work as control characters SPACE and DEL
   respectively, and code 0xA0 and 0xFF of GR area should not be used.

   There are two ways of invocation: locking-shift and single-shift.
   With locking-shift, the invocation lasts until the next different
   invocation, whereas with single-shift, the invocation works only
   for the following character and doesn't affect locking-shift.
   Invocations are done by the following control characters or escape
   sequences.

   ----------------------------------------------------------------------
   function		control char	escape sequence	description
   ----------------------------------------------------------------------
   SI  (shift-in)		0x0F	none		invoke G0 to GL
   SI  (shift-out)		0x0E	none		invoke G1 to GL
   LS2 (locking-shift-2)	none	ESC 'n'		invoke G2 into GL
   LS3 (locking-shift-3)	none	ESC 'o'		invoke G3 into GL
   SS2 (single-shift-2)		0x8E	ESC 'N'		invoke G2 into GL
   SS3 (single-shift-3)		0x8F	ESC 'O'		invoke G3 into GL
   ----------------------------------------------------------------------
   The first four are for locking-shift.  Control characters for these
   functions are defined by macros ISO_CODE_XXX in `coding.h'.

   Designations are done by the following escape sequences.
   ----------------------------------------------------------------------
   escape sequence	description
   ----------------------------------------------------------------------
   ESC '(' <F>		designate DIMENSION1_CHARS94<F> to G0
   ESC ')' <F>		designate DIMENSION1_CHARS94<F> to G1
   ESC '*' <F>		designate DIMENSION1_CHARS94<F> to G2
   ESC '+' <F>		designate DIMENSION1_CHARS94<F> to G3
   ESC ',' <F>		designate DIMENSION1_CHARS96<F> to G0 (*)
   ESC '-' <F>		designate DIMENSION1_CHARS96<F> to G1
   ESC '.' <F>		designate DIMENSION1_CHARS96<F> to G2
   ESC '/' <F>		designate DIMENSION1_CHARS96<F> to G3
   ESC '$' '(' <F>	designate DIMENSION2_CHARS94<F> to G0 (**)
   ESC '$' ')' <F>	designate DIMENSION2_CHARS94<F> to G1
   ESC '$' '*' <F>	designate DIMENSION2_CHARS94<F> to G2
   ESC '$' '+' <F>	designate DIMENSION2_CHARS94<F> to G3
   ESC '$' ',' <F>	designate DIMENSION2_CHARS96<F> to G0 (*)
   ESC '$' '-' <F>	designate DIMENSION2_CHARS96<F> to G1
   ESC '$' '.' <F>	designate DIMENSION2_CHARS96<F> to G2
   ESC '$' '/' <F>	designate DIMENSION2_CHARS96<F> to G3
   ----------------------------------------------------------------------

   In this list, "DIMENSION1_CHARS94<F>" means a graphic character set
   of dimension 1, chars 94, and final character <F>, and etc.

   Note (*): Although these designations are not allowed in ISO2022,
   Emacs accepts them on decoding, and produces them on encoding
   CHARS96 character set in a coding system which is characterized as
   7-bit environment, non-locking-shift, and non-single-shift.

   Note (**): If <F> is '@', 'A', or 'B', the intermediate character
   '(' can be omitted.  We call this as "short-form" here after.

   Now you may notice that there are a lot of ways for encoding the
Richard M. Stallman's avatar
Richard M. Stallman committed
567
   same multilingual text in ISO2022.  Actually, there exists many
Karl Heuer's avatar
Karl Heuer committed
568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598
   coding systems such as Compound Text (used in X's inter client
   communication, ISO-2022-JP (used in Japanese Internet), ISO-2022-KR
   (used in Korean Internet), EUC (Extended UNIX Code, used in Asian
   localized platforms), and all of these are variants of ISO2022.

   In addition to the above, Emacs handles two more kinds of escape
   sequences: ISO6429's direction specification and Emacs' private
   sequence for specifying character composition.

   ISO6429's direction specification takes the following format:
	o CSI ']'      -- end of the current direction
	o CSI '0' ']'  -- end of the current direction
	o CSI '1' ']'  -- start of left-to-right text
	o CSI '2' ']'  -- start of right-to-left text
   The control character CSI (0x9B: control sequence introducer) is
   abbreviated to the escape sequence ESC '[' in 7-bit environment.
   
   Character composition specification takes the following format:
	o ESC '0' -- start character composition
	o ESC '1' -- end character composition
   Since these are not standard escape sequences of any ISO, the use
   of them for these meaning is restricted to Emacs only.  */

enum iso_code_class_type iso_code_class[256];

/* See the above "GENERAL NOTES on `detect_coding_XXX ()' functions".
   Check if a text is encoded in ISO2022.  If it is, returns an
   integer in which appropriate flag bits any of:
	CODING_CATEGORY_MASK_ISO_7
	CODING_CATEGORY_MASK_ISO_8_1
	CODING_CATEGORY_MASK_ISO_8_2
599 600
	CODING_CATEGORY_MASK_ISO_7_ELSE
	CODING_CATEGORY_MASK_ISO_8_ELSE
Karl Heuer's avatar
Karl Heuer committed
601 602 603 604 605 606 607
   are set.  If a code which should never appear in ISO2022 is found,
   returns 0.  */

int
detect_coding_iso2022 (src, src_end)
     unsigned char *src, *src_end;
{
608 609 610
  int mask = (CODING_CATEGORY_MASK_ISO_7
	      | CODING_CATEGORY_MASK_ISO_8_1
	      | CODING_CATEGORY_MASK_ISO_8_2
611 612 613
	      | CODING_CATEGORY_MASK_ISO_7_ELSE
	      | CODING_CATEGORY_MASK_ISO_8_ELSE
	      );
614 615
  int g1 = 0;			/* 1 iff designating to G1.  */
  int c, i;
Karl Heuer's avatar
Karl Heuer committed
616

617
  while (src < src_end)
Karl Heuer's avatar
Karl Heuer committed
618 619 620 621 622
    {
      c = *src++;
      switch (c)
	{
	case ISO_CODE_ESC:
623
	  if (src >= src_end)
Karl Heuer's avatar
Karl Heuer committed
624 625
	    break;
	  c = *src++;
626
	  if (src < src_end
627 628 629
	      && ((c >= '(' && c <= '/')
		  || c == '$' && ((*src >= '(' && *src <= '/')
				  || (*src >= '@' && *src <= 'B'))))
Karl Heuer's avatar
Karl Heuer committed
630
	    {
631 632
	      /* Valid designation sequence.  */
	      if (c == ')' || (c == '$' && *src == ')'))
633 634
		{
		  g1 = 1;
635 636
		  mask &= ~(CODING_CATEGORY_MASK_ISO_7
			    | CODING_CATEGORY_MASK_ISO_7_ELSE);
637
		}
638 639
	      src++;
	      break;
Karl Heuer's avatar
Karl Heuer committed
640 641
	    }
	  else if (c == 'N' || c == 'O' || c == 'n' || c == 'o')
642 643
	    mask &= (CODING_CATEGORY_MASK_ISO_7_ELSE
		     | CODING_CATEGORY_MASK_ISO_8_ELSE);
Karl Heuer's avatar
Karl Heuer committed
644 645 646
	  break;

	case ISO_CODE_SO:
647
	  if (g1)
648 649
	    mask &= (CODING_CATEGORY_MASK_ISO_7_ELSE
		     | CODING_CATEGORY_MASK_ISO_8_ELSE);
650 651
	  break;
	  
Karl Heuer's avatar
Karl Heuer committed
652 653 654
	case ISO_CODE_CSI:
	case ISO_CODE_SS2:
	case ISO_CODE_SS3:
655 656
	  mask &= ~(CODING_CATEGORY_MASK_ISO_7
		    | CODING_CATEGORY_MASK_ISO_7_ELSE);
Karl Heuer's avatar
Karl Heuer committed
657 658 659 660 661 662 663 664 665
	  break;

	default:
	  if (c < 0x80)
	    break;
	  else if (c < 0xA0)
	    return 0;
	  else
	    {
666
	      unsigned char *src_begin = src;
Karl Heuer's avatar
Karl Heuer committed
667

668 669
	      mask &= ~(CODING_CATEGORY_MASK_ISO_7
			| CODING_CATEGORY_MASK_ISO_7_ELSE);
670
	      while (src < src_end && *src >= 0xA0)
671 672
		src++;
	      if ((src - src_begin - 1) & 1 && src < src_end)
Karl Heuer's avatar
Karl Heuer committed
673 674 675 676 677 678 679 680 681 682
		mask &= ~CODING_CATEGORY_MASK_ISO_8_2;
	    }
	  break;
	}
    }

  return mask;
}

/* Decode a character of which charset is CHARSET and the 1st position
683
   code is C1.  If dimension of CHARSET is 2, the 2nd position code is
Karl Heuer's avatar
Karl Heuer committed
684 685 686 687
   fetched from SRC and set to C2.  If CHARSET is negative, it means
   that we are decoding ill formed text, and what we can do is just to
   read C1 as is.  */

688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716
#define DECODE_ISO_CHARACTER(charset, c1)				\
  do {									\
    int c_alt, charset_alt = (charset);					\
    if (COMPOSING_HEAD_P (coding->composing))				\
      {									\
	*dst++ = LEADING_CODE_COMPOSITION;				\
	if (COMPOSING_WITH_RULE_P (coding->composing))			\
	  /* To tell composition rules are embeded.  */			\
	  *dst++ = 0xFF;						\
	coding->composing += 2;						\
      }									\
    if ((charset) >= 0)							\
      {									\
	if (CHARSET_DIMENSION (charset) == 2)				\
	  ONE_MORE_BYTE (c2);						\
	if (!NILP (unification_table)					\
	    && ((c_alt = unify_char (unification_table,			\
				     -1, (charset), c1, c2)) >= 0))	\
	  SPLIT_CHAR (c_alt, charset_alt, c1, c2);			\
      }									\
    if (charset_alt == CHARSET_ASCII || charset_alt < 0)		\
      DECODE_CHARACTER_ASCII (c1);					\
    else if (CHARSET_DIMENSION (charset_alt) == 1)			\
      DECODE_CHARACTER_DIMENSION1 (charset_alt, c1);			\
    else								\
      DECODE_CHARACTER_DIMENSION2 (charset_alt, c1, c2);		\
    if (COMPOSING_WITH_RULE_P (coding->composing))			\
      /* To tell a composition rule follows.  */			\
      coding->composing = COMPOSING_WITH_RULE_RULE;			\
Karl Heuer's avatar
Karl Heuer committed
717 718 719 720 721
  } while (0)

/* Set designation state into CODING.  */
#define DECODE_DESIGNATION(reg, dimension, chars, final_char)		\
  do {							      		\
722 723 724
    int charset = ISO_CHARSET_TABLE (make_number (dimension),		\
				     make_number (chars),		\
				     make_number (final_char));		\
Karl Heuer's avatar
Karl Heuer committed
725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755
    if (charset >= 0)					      		\
      {					      				\
        if (coding->direction == 1					\
	    && CHARSET_REVERSE_CHARSET (charset) >= 0)      		\
          charset = CHARSET_REVERSE_CHARSET (charset);      		\
        CODING_SPEC_ISO_DESIGNATION (coding, reg) = charset;		\
      }						      			\
  } while (0)

/* See the above "GENERAL NOTES on `decode_coding_XXX ()' functions".  */

int
decode_coding_iso2022 (coding, source, destination,
		       src_bytes, dst_bytes, consumed)
     struct coding_system *coding;
     unsigned char *source, *destination;
     int src_bytes, dst_bytes;
     int *consumed;
{
  unsigned char *src = source;
  unsigned char *src_end = source + src_bytes;
  unsigned char *dst = destination;
  unsigned char *dst_end = destination + dst_bytes;
  /* Since the maximum bytes produced by each loop is 7, we subtract 6
     from DST_END to assure that overflow checking is necessary only
     at the head of loop.  */
  unsigned char *adjusted_dst_end = dst_end - 6;
  int charset;
  /* Charsets invoked to graphic plane 0 and 1 respectively.  */
  int charset0 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 0);
  int charset1 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 1);
756 757
  Lisp_Object unification_table
      = coding->character_unification_table_for_decode;
758 759

  if (!NILP (Venable_character_unification) && NILP (unification_table))
760
    unification_table = Vstandard_character_unification_table_for_decode;
Karl Heuer's avatar
Karl Heuer committed
761 762 763 764 765 766 767 768 769

  while (src < src_end && dst < adjusted_dst_end)
    {
      /* SRC_BASE remembers the start position in source in each loop.
	 The loop will be exited when there's not enough source text
	 to analyze long escape sequence or 2-byte code (within macros
	 ONE_MORE_BYTE or TWO_MORE_BYTES).  In that case, SRC is reset
	 to SRC_BASE before exiting.  */
      unsigned char *src_base = src;
770
      int c1 = *src++, c2;
Karl Heuer's avatar
Karl Heuer committed
771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836

      switch (iso_code_class [c1])
	{
	case ISO_0x20_or_0x7F:
	  if (!coding->composing
	      && (charset0 < 0 || CHARSET_CHARS (charset0) == 94))
	    {
	      /* This is SPACE or DEL.  */
	      *dst++ = c1;
	      break;
	    }
	  /* This is a graphic character, we fall down ...  */

	case ISO_graphic_plane_0:
	  if (coding->composing == COMPOSING_WITH_RULE_RULE)
	    {
	      /* This is a composition rule.  */
	      *dst++ = c1 | 0x80;
	      coding->composing = COMPOSING_WITH_RULE_TAIL;
	    }
	  else
	    DECODE_ISO_CHARACTER (charset0, c1);
	  break;

	case ISO_0xA0_or_0xFF:
	  if (charset1 < 0 || CHARSET_CHARS (charset1) == 94)
	    {
	      /* Invalid code.  */
	      *dst++ = c1;
	      break;
	    }
	  /* This is a graphic character, we fall down ... */

	case ISO_graphic_plane_1:
	  DECODE_ISO_CHARACTER (charset1, c1);
	  break;

	case ISO_control_code:
	  /* All ISO2022 control characters in this class have the
             same representation in Emacs internal format.  */
	  *dst++ = c1;
	  break;

	case ISO_carriage_return:
	  if (coding->eol_type == CODING_EOL_CR)
	    {
	      *dst++ = '\n';
	    }
	  else if (coding->eol_type == CODING_EOL_CRLF)
	    {
	      ONE_MORE_BYTE (c1);
	      if (c1 == ISO_CODE_LF)
		*dst++ = '\n';
	      else
		{
		  src--;
		  *dst++ = c1;
		}
	    }
	  else
	    {
	      *dst++ = c1;
	    }
	  break;

	case ISO_shift_out:
837 838
	  if (CODING_SPEC_ISO_DESIGNATION (coding, 1) < 0)
	    goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874
	  CODING_SPEC_ISO_INVOCATION (coding, 0) = 1;
	  charset0 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 0);
	  break;

	case ISO_shift_in:
	  CODING_SPEC_ISO_INVOCATION (coding, 0) = 0;
	  charset0 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 0);
	  break;

	case ISO_single_shift_2_7:
	case ISO_single_shift_2:
	  /* SS2 is handled as an escape sequence of ESC 'N' */
	  c1 = 'N';
	  goto label_escape_sequence;

	case ISO_single_shift_3:
	  /* SS2 is handled as an escape sequence of ESC 'O' */
	  c1 = 'O';
	  goto label_escape_sequence;

	case ISO_control_sequence_introducer:
	  /* CSI is handled as an escape sequence of ESC '[' ...  */
	  c1 = '[';
	  goto label_escape_sequence;

	case ISO_escape:
	  ONE_MORE_BYTE (c1);
	label_escape_sequence:
	  /* Escape sequences handled by Emacs are invocation,
	     designation, direction specification, and character
	     composition specification.  */
	  switch (c1)
	    {
	    case '&':		/* revision of following character set */
	      ONE_MORE_BYTE (c1);
	      if (!(c1 >= '@' && c1 <= '~'))
875
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
876 877
	      ONE_MORE_BYTE (c1);
	      if (c1 != ISO_CODE_ESC)
878
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899
	      ONE_MORE_BYTE (c1);
	      goto label_escape_sequence;

	    case '$':		/* designation of 2-byte character set */
	      ONE_MORE_BYTE (c1);
	      if (c1 >= '@' && c1 <= 'B')
		{	/* designation of JISX0208.1978, GB2312.1980,
				   or JISX0208.1980 */
		  DECODE_DESIGNATION (0, 2, 94, c1);
		}
	      else if (c1 >= 0x28 && c1 <= 0x2B)
		{	/* designation of DIMENSION2_CHARS94 character set */
		  ONE_MORE_BYTE (c2);
		  DECODE_DESIGNATION (c1 - 0x28, 2, 94, c2);
		}
	      else if (c1 >= 0x2C && c1 <= 0x2F)
		{	/* designation of DIMENSION2_CHARS96 character set */
		  ONE_MORE_BYTE (c2);
		  DECODE_DESIGNATION (c1 - 0x2C, 2, 96, c2);
		}
	      else
900
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
901 902 903
	      break;

	    case 'n':		/* invocation of locking-shift-2 */
904 905
	      if (CODING_SPEC_ISO_DESIGNATION (coding, 2) < 0)
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
906
	      CODING_SPEC_ISO_INVOCATION (coding, 0) = 2;
907
	      charset0 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 0);
Karl Heuer's avatar
Karl Heuer committed
908 909 910
	      break;

	    case 'o':		/* invocation of locking-shift-3 */
911 912
	      if (CODING_SPEC_ISO_DESIGNATION (coding, 3) < 0)
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
913
	      CODING_SPEC_ISO_INVOCATION (coding, 0) = 3;
914
	      charset0 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 0);
Karl Heuer's avatar
Karl Heuer committed
915 916 917
	      break;

	    case 'N':		/* invocation of single-shift-2 */
918 919
	      if (CODING_SPEC_ISO_DESIGNATION (coding, 2) < 0)
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
920 921 922 923 924 925
	      ONE_MORE_BYTE (c1);
	      charset = CODING_SPEC_ISO_DESIGNATION (coding, 2);
	      DECODE_ISO_CHARACTER (charset, c1);
	      break;

	    case 'O':		/* invocation of single-shift-3 */
926 927
	      if (CODING_SPEC_ISO_DESIGNATION (coding, 3) < 0)
		goto label_invalid_escape_sequence;
Karl Heuer's avatar
Karl Heuer committed
928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027
	      ONE_MORE_BYTE (c1);
	      charset = CODING_SPEC_ISO_DESIGNATION (coding, 3);
	      DECODE_ISO_CHARACTER (charset, c1);
	      break;

	    case '0':		/* start composing without embeded rules */
	      coding->composing = COMPOSING_NO_RULE_HEAD;
	      break;

	    case '1':		/* end composing */
	      coding->composing = COMPOSING_NO;
	      break;

	    case '2':		/* start composing with embeded rules */
	      coding->composing = COMPOSING_WITH_RULE_HEAD;
	      break;

	    case '[':		/* specification of direction */
	      /* For the moment, nested direction is not supported.
		 So, the value of `coding->direction' is 0 or 1: 0
		 means left-to-right, 1 means right-to-left.  */
	      ONE_MORE_BYTE (c1);
	      switch (c1)
		{
		case ']':	/* end of the current direction */
		  coding->direction = 0;

		case '0':	/* end of the current direction */
		case '1':	/* start of left-to-right direction */
		  ONE_MORE_BYTE (c1);
		  if (c1 == ']')
		    coding->direction = 0;
		  else
		    goto label_invalid_escape_sequence;
		  break;

		case '2':	/* start of right-to-left direction */
		  ONE_MORE_BYTE (c1);
		  if (c1 == ']')
		    coding->direction= 1;
		  else
		    goto label_invalid_escape_sequence;
		  break;

		default:
		  goto label_invalid_escape_sequence;
		}
	      break;

	    default:
	      if (c1 >= 0x28 && c1 <= 0x2B)
		{	/* designation of DIMENSION1_CHARS94 character set */
		  ONE_MORE_BYTE (c2);
		  DECODE_DESIGNATION (c1 - 0x28, 1, 94, c2);
		}
	      else if (c1 >= 0x2C && c1 <= 0x2F)
		{	/* designation of DIMENSION1_CHARS96 character set */
		  ONE_MORE_BYTE (c2);
		  DECODE_DESIGNATION (c1 - 0x2C, 1, 96, c2);
		}
	      else
		{
		  goto label_invalid_escape_sequence;
		}
	    }
	  /* We must update these variables now.  */
	  charset0 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 0);
	  charset1 = CODING_SPEC_ISO_PLANE_CHARSET (coding, 1);
	  break;

	label_invalid_escape_sequence:
	  {
	    int length = src - src_base;

	    bcopy (src_base, dst, length);
	    dst += length;
	  }
	}
      continue;

    label_end_of_loop:
      coding->carryover_size = src - src_base;
      bcopy (src_base, coding->carryover, coding->carryover_size);
      src = src_base;
      break;
    }

  /* If this is the last block of the text to be decoded, we had
     better just flush out all remaining codes in the text although
     they are not valid characters.  */
  if (coding->last_block)
    {
      bcopy (src, dst, src_end - src);
      dst += (src_end - src);
      src = src_end;
    }
  *consumed = src - source;
  return dst - destination;
}

Richard M. Stallman's avatar
Richard M. Stallman committed
1028
/* ISO2022 encoding stuff.  */
Karl Heuer's avatar
Karl Heuer committed
1029 1030

/*
Richard M. Stallman's avatar
Richard M. Stallman committed
1031
   It is not enough to say just "ISO2022" on encoding, we have to
Karl Heuer's avatar
Karl Heuer committed
1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045
   specify more details.  In Emacs, each coding-system of ISO2022
   variant has the following specifications:
	1. Initial designation to G0 thru G3.
	2. Allows short-form designation?
	3. ASCII should be designated to G0 before control characters?
	4. ASCII should be designated to G0 at end of line?
	5. 7-bit environment or 8-bit environment?
	6. Use locking-shift?
	7. Use Single-shift?
   And the following two are only for Japanese:
	8. Use ASCII in place of JIS0201-1976-Roman?
	9. Use JISX0208-1983 in place of JISX0208-1978?
   These specifications are encoded in `coding->flags' as flag bits
   defined by macros CODING_FLAG_ISO_XXX.  See `coding.h' for more
Richard M. Stallman's avatar
Richard M. Stallman committed
1046
   details.
Karl Heuer's avatar
Karl Heuer committed
1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
*/

/* Produce codes (escape sequence) for designating CHARSET to graphic
   register REG.  If <final-char> of CHARSET is '@', 'A', or 'B' and
   the coding system CODING allows, produce designation sequence of
   short-form.  */

#define ENCODE_DESIGNATION(charset, reg, coding)			\
  do {									\
    unsigned char final_char = CHARSET_ISO_FINAL_CHAR (charset);	\
    char *intermediate_char_94 = "()*+";				\
    char *intermediate_char_96 = ",-./";				\
    Lisp_Object temp							\
      = Fassq (make_number (charset), Vcharset_revision_alist);		\
    if (! NILP (temp))							\
	{								\
	*dst++ = ISO_CODE_ESC;						\
	*dst++ = '&';							\
	*dst++ = XINT (XCONS (temp)->cdr) + '@';			\
      }									\
    *dst++ = ISO_CODE_ESC;				       		\
    if (CHARSET_DIMENSION (charset) == 1)				\
      {									\
	if (CHARSET_CHARS (charset) == 94)				\
	  *dst++ = (unsigned char) (intermediate_char_94[reg]);		\
	else								\
	  *dst++ = (unsigned char) (intermediate_char_96[reg]);		\
      }									\
    else								\
      {									\
	*dst++ = '$';							\
	if (CHARSET_CHARS (charset) == 94)				\
	  {								\
	    if (! (coding->flags & CODING_FLAG_ISO_SHORT_FORM)     	\
		|| reg != 0					       	\
		|| final_char < '@' || final_char > 'B')	       	\
	      *dst++ = (unsigned char) (intermediate_char_94[reg]);	\
	  }								\
	else								\
	  *dst++ = (unsigned char) (intermediate_char_96[reg]);  	\
      }									\
    *dst++ = final_char;				       		\
    CODING_SPEC_ISO_DESIGNATION (coding, reg) = charset;		\
  } while (0)

/* The following two macros produce codes (control character or escape
   sequence) for ISO2022 single-shift functions (single-shift-2 and
   single-shift-3).  */

#define ENCODE_SINGLE_SHIFT_2				\
  do {							\
    if (coding->flags & CODING_FLAG_ISO_SEVEN_BITS)	\
      *dst++ = ISO_CODE_ESC, *dst++ = 'N';		\
    else						\
      *dst++ = ISO_CODE_SS2;				\
    CODING_SPEC_ISO_SINGLE_SHIFTING (coding) = 1;	\
  } while (0)

#define ENCODE_SINGLE_SHIFT_3			   	\
  do {						   	\
    if (coding->flags & CODING_FLAG_ISO_SEVEN_BITS)	\
      *dst++ = ISO_CODE_ESC, *dst++ = 'O';	   	\
    else					   	\
      *dst++ = ISO_CODE_SS3;			   	\
    CODING_SPEC_ISO_SINGLE_SHIFTING (coding) = 1;	\
  } while (0)

/* The following four macros produce codes (control character or
   escape sequence) for ISO2022 locking-shift functions (shift-in,
   shift-out, locking-shift-2, and locking-shift-3).  */

#define ENCODE_SHIFT_IN			  	\
  do {					  	\
    *dst++ = ISO_CODE_SI;		  	\
    CODING_SPEC_ISO_INVOCATION (coding, 0) = 0;	\
  } while (0)

#define ENCODE_SHIFT_OUT		  	\
  do {					  	\
    *dst++ = ISO_CODE_SO;		  	\
    CODING_SPEC_ISO_INVOCATION (coding, 0) = 1;	\
  } while (0)

#define ENCODE_LOCKING_SHIFT_2			\
  do {						\
    *dst++ = ISO_CODE_ESC, *dst++ = 'n';	\
    CODING_SPEC_ISO_INVOCATION (coding, 0) = 2;	\
  } while (0)

#define ENCODE_LOCKING_SHIFT_3		  	\
  do {					  	\
    *dst++ = ISO_CODE_ESC, *dst++ = 'o';  	\
    CODING_SPEC_ISO_INVOCATION (coding, 0) = 3;	\
  } while (0)

Richard M. Stallman's avatar
Richard M. Stallman committed
1142 1143
/* Produce codes for a DIMENSION1 character whose character set is
   CHARSET and whose position-code is C1.  Designation and invocation
Karl Heuer's avatar
Karl Heuer committed
1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175
   sequences are also produced in advance if necessary.  */


#define ENCODE_ISO_CHARACTER_DIMENSION1(charset, c1)			\
  do {									\
    if (CODING_SPEC_ISO_SINGLE_SHIFTING (coding))			\
      {									\
	if (coding->flags & CODING_FLAG_ISO_SEVEN_BITS)			\
	  *dst++ = c1 & 0x7F;						\
	else								\
	  *dst++ = c1 | 0x80;						\
	CODING_SPEC_ISO_SINGLE_SHIFTING (coding) = 0;			\
	break;								\
      }									\
    else if (charset == CODING_SPEC_ISO_PLANE_CHARSET (coding, 0))	\
      {									\
	*dst++ = c1 & 0x7F;						\
	break;								\
      }									\
    else if (charset == CODING_SPEC_ISO_PLANE_CHARSET (coding, 1))	\
      {									\
	*dst++ = c1 | 0x80;						\
	break;								\
      }									\
    else								\
      /* Since CHARSET is not yet invoked to any graphic planes, we	\
	 must invoke it, or, at first, designate it to some graphic	\
	 register.  Then repeat the loop to actually produce the	\
	 character.  */							\
      dst = encode_invocation_designation (charset, coding, dst);	\
  } while (1)

Richard M. Stallman's avatar
Richard M. Stallman committed
1176 1177
/* Produce codes for a DIMENSION2 character whose character set is
   CHARSET and whose position-codes are C1 and C2.  Designation and
Karl Heuer's avatar
Karl Heuer committed
1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208
   invocation codes are also produced in advance if necessary.  */

#define ENCODE_ISO_CHARACTER_DIMENSION2(charset, c1, c2)		\
  do {									\
    if (CODING_SPEC_ISO_SINGLE_SHIFTING (coding))			\
      {									\
	if (coding->flags & CODING_FLAG_ISO_SEVEN_BITS)			\
	  *dst++ = c1 & 0x7F, *dst++ = c2 & 0x7F;			\
	else								\
	  *dst++ = c1 | 0x80, *dst++ = c2 | 0x80;			\
	CODING_SPEC_ISO_SINGLE_SHIFTING (coding) = 0;			\
	break;								\
      }									\
    else if (charset == CODING_SPEC_ISO_PLANE_CHARSET (coding, 0))	\
      {									\
	*dst++ = c1 & 0x7F, *dst++= c2 & 0x7F;				\
	break;								\
      }									\
    else if (charset == CODING_SPEC_ISO_PLANE_CHARSET (coding, 1))	\
      {									\
	*dst++ = c1 | 0x80, *dst++= c2 | 0x80;				\
	break;								\
      }									\
    else								\
      /* Since CHARSET is not yet invoked to any graphic planes, we	\
	 must invoke it, or, at first, designate it to some graphic	\
	 register.  Then repeat the loop to actually produce the	\
	 character.  */							\
      dst = encode_invocation_designation (charset, coding, dst);	\
  } while (1)

1209 1210 1211 1212 1213
#define ENCODE_ISO_CHARACTER(charset, c1, c2)				  \
  do {									  \
    int c_alt, charset_alt;						  \
    if (!NILP (unification_table)					  \
	&& ((c_alt = unify_char (unification_table, -1, charset, c1, c2)) \
1214
	    >= 0))							  \
1215 1216 1217 1218 1219 1220 1221 1222 1223
      SPLIT_CHAR (c_alt, charset_alt, c1, c2);				  \
    else								  \
      charset_alt = charset;						  \
    if (CHARSET_DIMENSION (charset_alt) == 1)				  \
      ENCODE_ISO_CHARACTER_DIMENSION1 (charset_alt, c1);		  \
    else								  \
      ENCODE_ISO_CHARACTER_DIMENSION2 (charset_alt, c1, c2);		  \
  } while (0)

Karl Heuer's avatar
Karl Heuer committed
1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245
/* Produce designation and invocation codes at a place pointed by DST
   to use CHARSET.  The element `spec.iso2022' of *CODING is updated.
   Return new DST.  */

unsigned char *
encode_invocation_designation (charset, coding, dst)
     int charset;
     struct coding_system *coding;
     unsigned char *dst;
{
  int reg;			/* graphic register number */

  /* At first, check designations.  */
  for (reg = 0; reg < 4; reg++)
    if (charset == CODING_SPEC_ISO_DESIGNATION (coding, reg))
      break;

  if (reg >= 4)
    {
      /* CHARSET is not yet designated to any graphic registers.  */
      /* At first check the requested designation.  */
      reg = CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset);
1246 1247 1248
      if (reg == CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION)
	/* Since CHARSET requests no special designation, designate it
	   to graphic register 0.  */
Karl Heuer's avatar
Karl Heuer committed
1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
	reg = 0;

      ENCODE_DESIGNATION (charset, reg, coding);
    }

  if (CODING_SPEC_ISO_INVOCATION (coding, 0) != reg
      && CODING_SPEC_ISO_INVOCATION (coding, 1) != reg)
    {
      /* Since the graphic register REG is not invoked to any graphic
	 planes, invoke it to graphic plane 0.  */
      switch (reg)
	{
	case 0:			/* graphic register 0 */
	  ENCODE_SHIFT_IN;
	  break;

	case 1:			/* graphic register 1 */
	  ENCODE_SHIFT_OUT;
	  break;

	case 2:			/* graphic register 2 */
	  if (coding->flags & CODING_FLAG_ISO_SINGLE_SHIFT)
	    ENCODE_SINGLE_SHIFT_2;
	  else
	    ENCODE_LOCKING_SHIFT_2;
	  break;

	case 3:			/* graphic register 3 */
	  if (coding->flags & CODING_FLAG_ISO_SINGLE_SHIFT)
	    ENCODE_SINGLE_SHIFT_3;
	  else
	    ENCODE_LOCKING_SHIFT_3;
	  break;
	}
    }
  return dst;
}

/* The following two macros produce codes for indicating composition.  */
#define ENCODE_COMPOSITION_NO_RULE_START  *dst++ = ISO_CODE_ESC, *dst++ = '0'
#define ENCODE_COMPOSITION_WITH_RULE_START  *dst++ = ISO_CODE_ESC, *dst++ = '2'
#define ENCODE_COMPOSITION_END    *dst++ = ISO_CODE_ESC, *dst++ = '1'

/* The following three macros produce codes for indicating direction
   of text.  */
#define ENCODE_CONTROL_SEQUENCE_INTRODUCER	    	\
  do {						    	\
    if (coding->flags == CODING_FLAG_ISO_SEVEN_BITS)	\
      *dst++ = ISO_CODE_ESC, *dst++ = '[';	    	\
    else					    	\
      *dst++ = ISO_CODE_CSI;			    	\
  } while (0)

#define ENCODE_DIRECTION_R2L	\
  ENCODE_CONTROL_SEQUENCE_INTRODUCER, *dst++ = '2', *dst++ = ']'

#define ENCODE_DIRECTION_L2R	\
  ENCODE_CONTROL_SEQUENCE_INTRODUCER, *dst++ = '0', *dst++ = ']'

/* Produce codes for designation and invocation to reset the graphic
   planes and registers to initial state.  */
1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320
#define ENCODE_RESET_PLANE_AND_REGISTER					    \
  do {									    \
    int reg;								    \
    if (CODING_SPEC_ISO_INVOCATION (coding, 0) != 0)			    \
      ENCODE_SHIFT_IN;							    \
    for (reg = 0; reg < 4; reg++)					    \
      if (CODING_SPEC_ISO_INITIAL_DESIGNATION (coding, reg) >= 0	    \
	  && (CODING_SPEC_ISO_DESIGNATION (coding, reg)			    \
	      != CODING_SPEC_ISO_INITIAL_DESIGNATION (coding, reg)))	    \
	ENCODE_DESIGNATION						    \
	  (CODING_SPEC_ISO_INITIAL_DESIGNATION (coding, reg), reg, coding); \
Karl Heuer's avatar
Karl Heuer committed
1321 1322
  } while (0)

1323 1324 1325 1326 1327 1328
/* Produce designation sequences of charsets in the line started from
   *SRC to a place pointed by DSTP.

   If the current block ends before any end-of-line, we may fail to
   find all the necessary *designations.  */
encode_designation_at_bol (coding, table, src, src_end, dstp)
1329
     struct coding_system *coding;
1330
     Lisp_Object table;
1331 1332
     unsigned char *src, *src_end, **dstp;
{
1333 1334 1335 1336 1337 1338 1339 1340 1341
  int charset, c, found = 0, reg;
  /* Table of charsets to be designated to each graphic register.  */
  int r[4];
  unsigned char *dst = *dstp;

  for (reg = 0; reg < 4; reg++)
    r[reg] = -1;

  while (src < src_end && *src != '\n' && found < 4)
1342
    {
1343 1344 1345 1346 1347
      int bytes = BYTES_BY_CHAR_HEAD (*src);
      
      if (NILP (table))
	charset = CHARSET_AT (src);
      else
1348
	{
1349 1350 1351 1352 1353
	  int c_alt, c1, c2;

	  SPLIT_STRING(src, bytes, charset, c1, c2);
	  if ((c_alt = unify_char (table, -1, charset, c1, c2)) >= 0)
	    charset = CHAR_CHARSET (c_alt);
1354
	}
1355

1356
      reg = CODING_SPEC_ISO_REQUESTED_DESIGNATION (coding, charset);
1357
      if (r[reg] == CODING_SPEC_ISO_NO_REQUESTED_DESIGNATION)
1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372
	{
	  found++;
	  r[reg] = charset;
	}

      src += bytes;
    }

  if (found)
    {
      for (reg = 0; reg < 4; reg++)
	if (r[reg] >= 0
	    && CODING_SPEC_ISO_DESIGNATION (coding, reg) != r[reg])
	  ENCODE_DESIGNATION (r[reg], reg, coding);
      *dstp = dst;
1373 1374 1375
    }
}

Karl Heuer's avatar
Karl Heuer committed
1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389
/* See the above "GENERAL NOTES on `encode_coding_XXX ()' functions".  */

int
encode_coding_iso2022 (coding, source, destination,
		       src_bytes, dst_bytes, consumed)
     struct coding_system *coding;
     unsigned char *source, *destination;
     int src_bytes, dst_bytes;
     int *consumed;
{
  unsigned char *src = source;
  unsigned char *src_end = source + src_bytes;
  unsigned char *dst = destination;
  unsigned char *dst_end = destination + dst_bytes;
1390
  /* Since the maximum bytes produced by each loop is 20, we subtract 19
Karl Heuer's avatar
Karl Heuer committed
1391 1392
     from DST_END to assure overflow checking is necessary only at the
     head of loop.  */
1393
  unsigned char *adjusted_dst_end = dst_end - 19;
1394 1395
  Lisp_Object unification_table
      = coding->character_unification_table_for_encode;
1396 1397

  if (!NILP (Venable_character_unification) && NILP (unification_table))
1398
    unification_table = Vstandard_character_unification_table_for_encode;
Karl Heuer's avatar
Karl Heuer committed
1399 1400 1401 1402 1403 1404 1405 1406 1407

  while (src < src_end && dst < adjusted_dst_end)
    {
      /* SRC_BASE remembers the start position in source in each loop.
	 The loop will be exited when there's not enough source text
	 to analyze multi-byte codes (within macros ONE_MORE_BYTE,
	 TWO_MORE_BYTES, and THREE_MORE_BYTES).  In that case, SRC is
	 reset to SRC_BASE before exiting.  */
      unsigned char *src_base = src;
1408
      int charset, c1, c2, c3, c4;
Karl Heuer's avatar
Karl Heuer committed
1409

1410 1411 1412
      if (coding->flags & CODING_FLAG_ISO_DESIGNATE_AT_BOL
	  && CODING_SPEC_ISO_BOL (coding))
	{
1413 1414 1415
	  /* We have to produce designation sequences if any now.  */
	  encode_designation_at_bol (coding, unification_table,
				     src, src_end, &dst);
1416 1417 1418 1419
	  CODING_SPEC_ISO_BOL (coding) = 0;
	}

      c1 = *src++;
Karl Heuer's avatar
Karl Heuer committed
1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459
      /* If we are seeing a component of a composite character, we are
	 seeing a leading-code specially encoded for composition, or a
	 composition rule if composing with rule.  We must set C1
	 to a normal leading-code or an ASCII code.  If we are not at
	 a composed character, we must reset the composition state.  */
      if (COMPOSING_P (coding->composing))
	{
	  if (c1 < 0xA0)
	    {
	      /* We are not in a composite character any longer.  */
	      coding->composing = COMPOSING_NO;
	      ENCODE_COMPOSITION_END;
	    }
	  else
	    {
	      if (coding->composing == COMPOSING_WITH_RULE_RULE)
		{
		  *dst++ = c1 & 0x7F;
		  coding->composing = COMPOSING_WITH_RULE_HEAD;
		  continue;
		}
	      else if (coding->composing == COMPOSING_WITH_RULE_HEAD)
		coding->composing = COMPOSING_WITH_RULE_RULE;
	      if (c1 == 0xA0)
		{
		  /* This is an ASCII component.  */
		  ONE_MORE_BYTE (c1);
		  c1 &= 0x7F;
		}
	      else
		/* This is a leading-code of non ASCII component.  */
		c1 -= 0x20;
	    }
	}
	
      /* Now encode one character.  C1 is a control character, an
         ASCII character, or a leading-code of multi-byte character.  */
      switch (emacs_code_class[c1])
	{
	case EMACS_ascii_code:
1460
	  ENCODE_ISO_CHARACTER (CHARSET_ASCII, c1, /* dummy */ c2);
Karl Heuer's avatar
Karl Heuer committed
1461 1462 1463 1464
	  break;

	case EMACS_control_code:
	  if (coding->flags & CODING_FLAG_ISO_RESET_AT_CNTL)
1465
	    ENCODE_RESET_PLANE_AND_REGISTER;
Karl Heuer's avatar
Karl Heuer committed
1466 1467 1468 1469 1470 1471 1472
	  *dst++ = c1;
	  break;

	case EMACS_carriage_return_code:
	  if (!coding->selective)
	    {
	      if (coding->flags & CODING_FLAG_ISO_RESET_AT_CNTL)
1473
		ENCODE_RESET_PLANE_AND_REGISTER;
Karl Heuer's avatar
Karl Heuer committed
1474 1475 1476 1477 1478 1479 1480
	      *dst++ = c1;
	      break;
	    }
	  /* fall down to treat '\r' as '\n' ...  */

	case EMACS_linefeed_code:
	  if (coding->flags & CODING_FLAG_ISO_RESET_AT_EOL)
1481 1482 1483 1484 1485
	    ENCODE_RESET_PLANE_AND_REGISTER;
	  if (coding->flags & CODING_FLAG_ISO_INIT_AT_BOL)
	    bcopy (coding->spec.iso2022.initial_designation,
		   coding->spec.iso2022.current_designation,
		   sizeof coding->spec.iso2022.initial_designation);
Karl Heuer's avatar
Karl Heuer committed
1486
	  if (coding->eol_type == CODING_EOL_LF
Kenichi Handa's avatar
Kenichi Handa committed
1487
	      || coding->eol_type == CODING_EOL_UNDECIDED)
Karl Heuer's avatar
Karl Heuer committed
1488 1489 1490 1491 1492
	    *dst++ = ISO_CODE_LF;
	  else if (coding->eol_type == CODING_EOL_CRLF)
	    *dst++ = ISO_CODE_CR, *dst++ = ISO_CODE_LF;
	  else
	    *dst++ = ISO_CODE_CR;
1493
	  CODING_SPEC_ISO_BOL (coding) = 1;
Karl Heuer's avatar
Karl Heuer committed
1494 1495 1496 1497
	  break;

	case EMACS_leading_code_2:
	  ONE_MORE_BYTE (c2);
1498 1499 1500 1501 1502 1503 1504 1505
	  if (c2 < 0xA0)
	    {
	      /* invalid sequence */
	      *dst++ = c1;
	      *dst++ = c2;
	    }
	  else
	    ENCODE_ISO_CHARACTER (c1, c2, /* dummy */ c3);
Karl Heuer's avatar
Karl Heuer committed
1506 1507 1508 1509
	  break;

	case EMACS_leading_code_3:
	  TWO_MORE_BYTES (c2, c3);
1510 1511 1512 1513 1514 1515 1516 1517
	  if (c2 < 0xA0 || c3 < 0xA0)
	    {
	      /* invalid sequence */
	      *dst++ = c1;
	      *dst++ = c2;
	      *dst++ = c3;
	    }
	  else if (c1 < LEADING_CODE_PRIVATE_11)
1518
	    ENCODE_ISO_CHARACTER (c1, c2, c3);
Karl Heuer's avatar
Karl Heuer committed
1519
	  else
1520
	    ENCODE_ISO_CHARACTER (c2, c3, /* dummy */ c4);
Karl Heuer's avatar
Karl Heuer committed
1521 1522 1523 1524
	  break;

	case EMACS_leading_code_4:
	  THREE_MORE_BYTES (c2, c3, c4);
1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
	  if (c2 < 0xA0 || c3 < 0xA0 || c4 < 0xA0)
	    {
	      /* invalid sequence */
	      *dst++ = c1;
	      *dst++ = c2;
	      *dst++ = c3;
	      *dst++ = c4;
	    }
	  else
	    ENCODE_ISO_CHARACTER (c2, c3, c4);
Karl Heuer's avatar
Karl Heuer committed
1535 1536 1537
	  break;

	case EMACS_leading_code_composition:
1538 1539 1540 1541 1542 1543 1544 1545
	  ONE_MORE_BYTE (c2);
	  if (c2 < 0xA0)
	    {
	      /* invalid sequence */
	      *dst++ = c1;
	      *dst++ = c2;
	    }
	  else if (c2 == 0xFF)
Karl Heuer's avatar
Karl Heuer committed
1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
	    {
	      coding->composing = COMPOSING_WITH_RULE_HEAD;
	      ENCODE_COMPOSITION_WITH_RULE_START;
	    }
	  else
	    {
	      /* Rewind one byte because it is a character code of
                 composition elements.  */
	      src--;
	      coding->composing = COMPOSING_NO_RULE_HEAD;
	      ENCODE_COMPOSITION_NO_RULE_START;
	    }
	  break;

	case EMACS_invalid_code:
	  *dst++ = c1;
	  break;
	}
      continue;
    label_end_of_loop:
1566 1567 1568
      /* We reach here because the source date ends not at character
	 boundary.  */
      coding->carryover_size = src_end - src_base;
Karl Heuer's avatar
Karl Heuer committed
1569
      bcopy (src_base, coding->carryover, coding->carryover_size);
1570
      src = src_end;
Karl Heuer's avatar
Karl Heuer committed
1571 1572 1573 1574
      break;
    }

  /* If this is the last block of the text to be encoded, we must
1575 1576
     reset graphic planes and registers to the initial state.  */
  if (src >= src_end && coding->last_block)
Karl Heuer's avatar
Karl Heuer committed
1577
    {
1578
      ENCODE_RESET_PLANE_AND_REGISTER;
1579 1580 1581 1582 1583 1584 1585
      if (coding->carryover_size > 0
	  && coding->carryover_size < (dst_end - dst))
	{
	  bcopy (coding->carryover, dst, coding->carryover_size);
	  dst += coding->carryover_size;
	  coding->carryover_size = 0;
	}
Karl Heuer's avatar
Karl Heuer committed
1586 1587 1588 1589 1590 1591 1592 1593
    }
  *consumed = src - source;
  return dst - destination;
}


/*** 4. SJIS and BIG5 handlers ***/

Richard M. Stallman's avatar
Richard M. Stallman committed
1594
/* Although SJIS and BIG5 are not ISO's coding system, they are used
Karl Heuer's avatar
Karl Heuer committed
1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665
   quite widely.  So, for the moment, Emacs supports them in the bare
   C code.  But, in the future, they may be supported only by CCL.  */

/* SJIS is a coding system encoding three character sets: ASCII, right
   half of JISX0201-Kana, and JISX0208.  An ASCII character is encoded
   as is.  A character of charset katakana-jisx0201 is encoded by
   "position-code + 0x80".  A character of charset japanese-jisx0208
   is encoded in 2-byte but two position-codes are divided and shifted
   so that it fit in the range below.

   --- CODE RANGE of SJIS ---
   (character set)	(range)
   ASCII		0x00 .. 0x7F
   KATAKANA-JISX0201	0xA0 .. 0xDF
   JISX0208 (1st byte)	0x80 .. 0x9F and 0xE0 .. 0xFF
	    (2nd byte)	0x40 .. 0xFF
   -------------------------------

*/

/* BIG5 is a coding system encoding two character sets: ASCII and
   Big5.  An ASCII character is encoded as is.  Big5 is a two-byte
   character set and is encoded in two-byte.

   --- CODE RANGE of BIG5 ---
   (character set)	(range)
   ASCII		0x00 .. 0x7F
   Big5 (1st byte)	0xA1 .. 0xFE
	(2nd byte)	0x40 .. 0x7E and 0xA1 .. 0xFE
   --------------------------

   Since the number of characters in Big5 is larger than maximum
   characters in Emacs' charset (96x96), it can't be handled as one
   charset.  So, in Emacs, Big5 is divided into two: `charset-big5-1'
   and `charset-big5-2'.  Both are DIMENSION2 and CHARS94.  The former
   contains frequently used characters and the latter contains less
   frequently used characters.  */

/* Macros to decode or encode a character of Big5 in BIG5.  B1 and B2
   are the 1st and 2nd position-codes of Big5 in BIG5 coding system.
   C1 and C2 are the 1st and 2nd position-codes of of Emacs' internal
   format.  CHARSET is `charset_big5_1' or `charset_big5_2'.  */

/* Number of Big5 characters which have the same code in 1st byte.  */
#define BIG5_SAME_ROW (0xFF - 0xA1 + 0x7F - 0x40)

#define DECODE_BIG5(b1, b2, charset, c1, c2)			     	\
  do {								     	\
    unsigned int temp						     	\
      = (b1 - 0xA1) * BIG5_SAME_ROW + b2 - (b2 < 0x7F ? 0x40 : 0x62);	\
    if (b1 < 0xC9)						     	\
      charset = charset_big5_1;					     	\
    else							     	\
      {								     	\
	charset = charset_big5_2;				     	\
	temp -= (0xC9 - 0xA1) * BIG5_SAME_ROW;			     	\
      }								     	\
    c1 = temp / (0xFF - 0xA1) + 0x21;				     	\
    c2 = temp % (0xFF - 0xA1) + 0x21;				     	\
  } while (0)

#define ENCODE_BIG5(charset, c1, c2, b1, b2)			  	\
  do {								  	\
    unsigned int temp = (c1 - 0x21) * (0xFF - 0xA1) + (c2 - 0x21);	\
    if (charset == charset_big5_2)				  	\
      temp += BIG5_SAME_ROW * (0xC9 - 0xA1);			  	\
    b1 = temp / BIG5_SAME_ROW + 0xA1;				  	\
    b2 = temp % BIG5_SAME_ROW;					  	\
    b2 += b2 < 0x3F ? 0x40 : 0x62;				  	\
  } while (0)

1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714
#define DECODE_SJIS_BIG5_CHARACTER(charset, c1, c2)			\
  do {									\
    int c_alt, charset_alt = (charset);					\
    if (!NILP (unification_table)					\
	&& ((c_alt = unify_char (unification_table,			\
				 -1, (charset), c1, c2)) >= 0))		\
	  SPLIT_CHAR (c_alt, charset_alt, c1, c2);			\
    if (charset_alt == CHARSET_ASCII || charset_alt < 0)		\
      DECODE_CHARACTER_ASCII (c1);					\
    else if (CHARSET_DIMENSION (charset_alt) == 1)			\
      DECODE_CHARACTER_DIMENSION1 (charset_alt, c1);			\
    else								\
      DECODE_CHARACTER_DIMENSION2 (charset_alt, c1, c2);		\
  } while (0)

#define ENCODE_SJIS_BIG5_CHARACTER(charset, c1, c2)			  \
  do {									  \
    int c_alt, charset_alt;						  \
    if (!NILP (unification_table)					  \
        && ((c_alt = unify_char (unification_table, -1, charset, c1, c2)) \
	    >= 0))							  \
      SPLIT_CHAR (c_alt, charset_alt, c1, c2);				  \
    else								  \
      charset_alt = charset;						  \
    if (charset_alt == charset_ascii)					  \
      *dst++ = c1;							  \
    else if (CHARSET_DIMENSION (charset_alt) == 1)			  \
      {									  \
	if (sjis_p && charset_alt == charset_katakana_jisx0201)		  \
	  *dst++ = c1;							  \
	else								  \
	  *dst++ = charset_alt, *dst++ = c1;				  \
      }									  \
    else								  \
      {									  \
	c1 &= 0x7F, c2 &= 0x7F;						  \
	if (sjis_p && charset_alt == charset_jisx0208)			  \
	  {								  \
	    unsigned char s1, s2;					  \
									  \
	    ENCODE_SJIS (c1, c2, s1, s2);				  \
	    *dst++ = s1, *dst++ = s2;					  \
	  }								  \
	else if (!sjis_p						  \
		 && (charset_alt == charset_big5_1			  \
		     || charset_alt == charset_big5_2))			  \
	  {								  \
	    unsigned char b1, b2;					  \
									  \
1715
	    ENCODE_BIG5 (charset_alt, c1, c2, b1, b2);			  \
1716 1717 1718 1719 1720 1721 1722
	    *dst++ = b1, *dst++ = b2;					  \
	  }								  \
	else								  \
	  *dst++ = charset_alt, *dst++ = c1, *dst++ = c2;		  \
      }									  \
  } while (0);

Karl Heuer's avatar
Karl Heuer committed
1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793
/* See the above "GENERAL NOTES on `detect_coding_XXX ()' functions".
   Check if a text is encoded in SJIS.  If it is, return
   CODING_CATEGORY_MASK_SJIS, else return 0.  */

int
detect_coding_sjis (src, src_end)
     unsigned char *src, *src_end;
{
  unsigned char c;

  while (src < src_end)
    {
      c = *src++;
      if (c == ISO_CODE_ESC || c == ISO_CODE_SI || c == ISO_CODE_SO)
	return 0;