pith/escapes.c

   1 /*
   2  * ========================================================================
   3  * Copyright 2013-2022 Eduardo Chappa
   4  * Copyright 2006 University of Washington
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * ========================================================================
  13  */
  14
  15 /*======================================================================
  16
  17      escapes.c
  18      Implements known escape code matching
  19
  20   ====*/
  21
  22
  23 #include "../pith/headers.h"
  24 #include "../pith/escapes.h"
  25
  26
  27
  28 /*------------------------------------------------------------------
  29    This list of known escape sequences is taken from RFC's 1486 and 1554
  30    and draft-apng-cc-encoding, and the X11R5 source with only a remote
  31    understanding of what this all means...
  32
  33    NOTE: if the length of these should extend beyond 4 chars, fix
  34          MAX_ESC_LEN in filter.c
  35   ----*/
  36 #ifdef  _WINDOWS
  37 static char *known_escapes[] = {
  38     "(B",  "(J",  "$@",  "$B",                  /* RFC 1468 */
  39     "(H",
  40     NULL};
  41 #else
  42 static char *known_escapes[] = {
  43     "(B",  "(J",  "$@",  "$B",                  /* RFC 1468 */
  44     "(H",
  45     "$A",  "$(C", "$(D", ".A",  ".F",           /* added by RFC 1554 */
  46     "$)C", "$)A", "$*E", "$*X",                 /* those in apng-draft */
  47     "$+G", "$+H", "$+I", "$+J", "$+K",
  48     "$+L", "$+M",
  49     ")I",   "-A",  "-B",  "-C",  "-D",          /* codes form X11R5 source */
  50     "-F",   "-G",  "-H",   "-L",  "-M",
  51     "-$(A", "$(B", "$)B", "$)D",
  52     NULL};
  53 #endif
  54
  55
  56 int
  57 match_escapes(char *esc_seq)
  58 {
  59     char **p;
  60     int    n;
  61
  62     for(p = known_escapes; *p && strncmp(esc_seq, *p, n = strlen(*p)); p++)
  63       ;
  64
  65     return(*p ? n + 1 : 0);
  66 }