roff.h

   1 /*
   2  * Most functions and variables in neatroff are prefixed with tokens
   3  * that indicate their purpose, such as:
   4  *
   5  * + tr_xyz: the implementation of troff request .xyz (mostly tr.c)
   6  * + in_xyz: input layer (in.c)
   7  * + cp_xyz: copy-mode interpretation layer (cp.c)
   8  * + ren_xyz: rendering characters into lines (ren.c)
   9  * + out_xyz: output layer for generating troff output (out.c)
  10  * + dev_xyz: output devices (dev.c)
  11  * + num_xyz: number registers (reg.c)
  12  * + str_xyz: string registers (reg.c)
  13  * + env_xyz: environments (reg.c)
  14  * + eval_xyz: integer expression evaluation (eval.c)
  15  * + font_xyz: fonts (font.c)
  16  * + sbuf_xyz: variable length string buffers (sbuf.c)
  17  * + wb_xyz: word buffers (wb.c)
  18  * + fmt_xyz: line formatting buffers (fmt.c)
  19  * + n_xyz: builtin number register xyz
  20  * + c_xyz: characters for requests like hc and mc
  21  *
  22  */
  23
  24 /* predefined array limits */
  25 #define PATHLEN         1024    /* path length */
  26 #define NFILES          16      /* number of input files */
  27 #define NFONTS          32      /* number of fonts */
  28 #define NGLYPHS         1024    /* glyphs in fonts */
  29 #define NLIGS           128     /* number of font ligatures */
  30 #define NKERNS          1024    /* number of font kerning pairs */
  31 #define FNLEN           32      /* font name length */
  32 #define NMLEN           32      /* macro/register/environment/glyph name length */
  33 #define GNLEN           NMLEN   /* glyph name length */
  34 #define RNLEN           NMLEN   /* register/macro name */
  35 #define ILNLEN          1000    /* line limit of input files */
  36 #define LNLEN           4000    /* line buffer length (ren.c/out.c) */
  37 #define NWORDS          1024    /* number of queued words in formatting buffer */
  38 #define NLINES          32      /* number of queued lines in formatting buffer */
  39 #define NARGS           16      /* number of macro arguments */
  40 #define NPREV           16      /* environment stack depth */
  41 #define NTRAPS          1024    /* number of traps per page */
  42 #define NIES            128     /* number of nested .ie commands */
  43 #define NTABS           16      /* number of tab stops */
  44 #define NCMAPS          512     /* number of character translations (.tr) */
  45 #define NSSTR           32      /* number of nested sstr_push() calls */
  46 #define NFIELDS         32      /* number of fields */
  47 #define MAXFRAC         100000  /* maximum value of the fractional part */
  48 #define LIGLEN          4       /* length of ligatures */
  49 #define NCDEFS          128     /* number of character definitions (.char) */
  50 #define NHYPHS          16384   /* hyphenation dictionary/patterns (.hw) */
  51 #define NHYPHSWORD      16      /* number of hyphenations per word */
  52
  53 /* converting scales */
  54 #define SC_IN           (dev_res)       /* inch in units */
  55 #define SC_PT           (SC_IN / 72)    /* point in units */
  56 #define SC_EM           (n_s * SC_IN / 72)
  57
  58 /* escape sequences */
  59 #define ESC_Q   "bCDhHlLNoRSvwxX?"      /* \X'ccc' quoted escape sequences */
  60 #define ESC_P   "*fgkmns"               /* \Xc \X(cc \X[ccc] escape sequences */
  61
  62 #define MIN(a, b)       ((a) < (b) ? (a) : (b))
  63 #define MAX(a, b)       ((a) < (b) ? (b) : (a))
  64 #define LEN(a)          (sizeof(a) / sizeof((a)[0]))
  65
  66 /* special characters */
  67 extern int c_ec;        /* escape character (\) */
  68 extern int c_cc;        /* basic control character (.) */
  69 extern int c_c2;        /* no-break control character (') */
  70 #define c_ni    4       /* non-interpreted copy-mode escape */
  71 #define c_hc    env_hc()/* hyphenation character */
  72 #define c_mc    env_mc()/* margin character (.mc) */
  73 #define c_tc    env_tc()
  74 #define c_lc    env_lc()
  75 #define c_bp    "\\:"   /* zero-width word break point */
  76
  77 /* number registers */
  78 int num_get(int id, int inc);
  79 void num_set(int id, int val);
  80 void num_inc(int id, int val);
  81 void num_del(int id);
  82 char *num_str(int id);
  83 char *num_getfmt(int id);
  84 void num_setfmt(int id, char *fmt);
  85 int *nreg(int id);
  86 int eval(char *s, int unit);
  87 int eval_up(char **s, int unit);
  88 int eval_re(char *s, int orig, int unit);
  89
  90 /* string registers */
  91 void str_set(int id, char *s);
  92 void str_dset(int id, void *d);
  93 char *str_get(int id);
  94 void *str_dget(int id);
  95 void str_rm(int id);
  96 void str_rn(int src, int dst);
  97
  98 /* saving and restoring registers before and after printing diverted lines */
  99 void odiv_beg(void);
 100 void odiv_end(void);
 101
 102 /* enviroments */
 103 void env_init(void);
 104 void env_done(void);
 105 struct fmt *env_fmt(void);
 106 struct wb *env_wb(void);
 107 char *env_hc(void);
 108 char *env_mc(void);
 109 char *env_tc(void);
 110 char *env_lc(void);
 111 int tab_next(int pos);
 112 int tab_type(int pos);
 113
 114 /* device related variables */
 115 extern int dev_res;
 116 extern int dev_uwid;
 117 extern int dev_hor;
 118 extern int dev_ver;
 119
 120 struct glyph {
 121         char id[GNLEN];         /* device-dependent glyph identifier */
 122         char name[GNLEN];       /* the first character mapped to this glyph */
 123         struct font *font;      /* glyph font */
 124         int wid;                /* character width */
 125         int type;               /* character type; ascender/descender */
 126         int llx, lly, urx, ury; /* character bounding box */
 127 };
 128
 129 struct font {
 130         char name[FNLEN];
 131         char fontname[FNLEN];
 132         struct glyph glyphs[NGLYPHS];
 133         int nglyphs;
 134         int spacewid;
 135         int special;
 136         int cs, bd;                     /* for .cs and .bd requests */
 137         /* charset section characters */
 138         char c[NGLYPHS][GNLEN];         /* character names in charset */
 139         struct glyph *g[NGLYPHS];       /* character glyphs in charset */
 140         struct glyph *g_map[NGLYPHS];   /* character remapped via font_map() */
 141         int n;                          /* number of characters in charset */
 142         /* glyph table based on the first character of their id fields in glyphs[] */
 143         int ghead[256];                 /* glyph list heads */
 144         int gnext[NGLYPHS];             /* next item in glyph lists */
 145         /* character table based on the first character of glyph names in c[] */
 146         int chead[256];                 /* character list heads */
 147         int cnext[NGLYPHS];             /* next item in character lists */
 148         /* font ligatures (lg*) */
 149         char lg[NLIGS][LIGLEN * GNLEN]; /* ligatures */
 150         int lgn;                        /* number of ligatures in lg[] */
 151         /* kerning pair table per glyph (kn*) */
 152         int knhead[NGLYPHS];            /* kerning pairs of glyphs[] */
 153         int knnext[NKERNS];             /* next item in knhead[] list */
 154         int knpair[NKERNS];             /* kerning pair 2nd glyphs */
 155         int knval[NKERNS];              /* font pairwise kerning value */
 156         int knn;                        /* number of kerning pairs */
 157 };
 158
 159 /* output device functions */
 160 int dev_open(char *dir, char *dev);
 161 void dev_close(void);
 162 int dev_mnt(int pos, char *id, char *name);
 163 int dev_pos(char *id);
 164 struct font *dev_font(int pos);
 165 int dev_fontpos(struct font *fn);
 166 void dev_setcs(int fn, int cs);
 167 int dev_getcs(int fn);
 168 void dev_setbd(int fn, int bd);
 169 int dev_getbd(int fn);
 170
 171 /* font-related functions */
 172 struct font *font_open(char *path);
 173 void font_close(struct font *fn);
 174 struct glyph *font_glyph(struct font *fn, char *id);
 175 struct glyph *font_find(struct font *fn, char *name);
 176 int font_lig(struct font *fn, char **c, int n);
 177 int font_kern(struct font *fn, char *c1, char *c2);
 178 int font_islig(struct font *fn, char *s);
 179 int font_map(struct font *fn, char *name, struct glyph *gl);
 180 int font_mapped(struct font *fn, char *name);
 181
 182 /* glyph handling functions */
 183 struct glyph *dev_glyph(char *c, int fn);
 184 int charwid(int fn, int sz, int wid);
 185
 186 /* convert wid in device unitwidth size to size sz */
 187 #define DEVWID(sz, wid)         (((wid) * (sz) + (dev_uwid / 2)) / dev_uwid)
 188 /* the amount of word and sentence space for the given font and size */
 189 #define N_SS(fn, sz)    (charwid((fn), (sz), (dev_font(fn)->spacewid * n_ss + 6) / 12))
 190 #define N_SSS(fn, sz)   (charwid((fn), (sz), (dev_font(fn)->spacewid * n_sss + 6) / 12))
 191
 192 /* different layers of neatroff */
 193 int in_next(void);              /* input layer */
 194 int cp_next(void);              /* copy-mode layer */
 195 int tr_next(void);              /* troff layer */
 196
 197 void in_push(char *s, char **args);
 198 void in_pushnl(char *s, char **args);
 199 void in_so(char *path);         /* .so request */
 200 void in_nx(char *path);         /* .nx request */
 201 void in_ex(void);               /* .ex request */
 202 void in_lf(char *path, int ln); /* .lf request */
 203 void in_queue(char *path);      /* queue the given input file */
 204 char *in_arg(int i);            /* look up argument */
 205 int in_nargs(void);             /* number of arguments */
 206 void in_back(int c);            /* push back input character */
 207 int in_top(void);               /* the first pushed-back character */
 208 char *in_filename(void);        /* current filename */
 209 int in_lnum(void);              /* current line number */
 210
 211 void cp_blk(int skip);          /* skip or read the next line or block */
 212 void cp_copymode(int mode);     /* do not interpret \w and \E */
 213 #define cp_back         in_back /* cp.c is stateless */
 214 int tr_nextreq(void);           /* read the next troff request */
 215
 216 /* variable length string buffer */
 217 struct sbuf {
 218         char *s;                /* allocated buffer */
 219         int sz;                 /* buffer size */
 220         int n;                  /* length of the string stored in s */
 221 };
 222
 223 void sbuf_init(struct sbuf *sbuf);
 224 void sbuf_done(struct sbuf *sbuf);
 225 char *sbuf_buf(struct sbuf *sbuf);
 226 void sbuf_add(struct sbuf *sbuf, int c);
 227 void sbuf_append(struct sbuf *sbuf, char *s);
 228 void sbuf_printf(struct sbuf *sbuf, char *s, ...);
 229 void sbuf_putnl(struct sbuf *sbuf);
 230 void sbuf_cut(struct sbuf *sbuf, int n);
 231 int sbuf_len(struct sbuf *sbuf);
 232 int sbuf_empty(struct sbuf *sbuf);
 233
 234 /* word buffer */
 235 struct wb {
 236         struct sbuf sbuf;
 237         int f, s, m;            /* the last output font and size */
 238         int r_f, r_s, r_m;      /* current font and size; use n_f and n_s if -1 */
 239         int part;               /* partial input (\c) */
 240         int els_neg, els_pos;   /* extra line spacing */
 241         int h, v;               /* buffer vertical and horizontal positions */
 242         int ct, sb, st;         /* \w registers */
 243         int llx, lly, urx, ury; /* bounding box */
 244         int icleft_ll;          /* len after the pending left italic correction */
 245         /* saving previous characters added via wb_put() */
 246         char prev_c[LIGLEN][GNLEN];
 247         int prev_l[LIGLEN];     /* sbuf_len(&wb->sbuf) before wb_put() calls */
 248         int prev_h[LIGLEN];     /* wb->h before wb_put() calls */
 249         int prev_n;             /* number of characters in prev_c[] */
 250         int prev_ll;            /* sbuf_len(&wb->sbuf) after the last wb_put() */
 251 };
 252
 253 void wb_init(struct wb *wb);
 254 void wb_done(struct wb *wb);
 255 void wb_hmov(struct wb *wb, int n);
 256 void wb_vmov(struct wb *wb, int n);
 257 void wb_els(struct wb *wb, int els);
 258 void wb_etc(struct wb *wb, char *x);
 259 void wb_put(struct wb *wb, char *c);
 260 void wb_putexpand(struct wb *wb, char *c);
 261 int wb_part(struct wb *wb);
 262 void wb_setpart(struct wb *wb);
 263 void wb_drawl(struct wb *wb, int c, int h, int v);
 264 void wb_drawc(struct wb *wb, int c, int r);
 265 void wb_drawe(struct wb *wb, int c, int h, int v);
 266 void wb_drawa(struct wb *wb, int c, int h1, int v1, int h2, int v2);
 267 void wb_drawxbeg(struct wb *wb, int c);
 268 void wb_drawxdot(struct wb *wb, int h, int v);
 269 void wb_drawxend(struct wb *wb);
 270 void wb_italiccorrection(struct wb *wb);
 271 void wb_italiccorrectionleft(struct wb *wb);
 272 void wb_cat(struct wb *wb, struct wb *src);
 273 void wb_catstr(struct wb *wb, char *beg, char *end);
 274 int wb_hyphmark(char *word, int *hyidx, int *hyins);
 275 int wb_hyph(char *word, int *hyidx, int flg);
 276 int wb_wid(struct wb *wb);
 277 int wb_dashwid(struct wb *wb);
 278 int wb_empty(struct wb *wb);
 279 int wb_eos(struct wb *wb);
 280 void wb_wconf(struct wb *wb, int *ct, int *st, int *sb,
 281                 int *llx, int *lly, int *urx, int *ury);
 282 int wb_lig(struct wb *wb, char *c);
 283 int wb_kern(struct wb *wb, char *c);
 284 void wb_reset(struct wb *wb);
 285 char *wb_buf(struct wb *wb);
 286 void wb_fnszget(struct wb *wb, int *fn, int *sz, int *m);
 287 void wb_fnszset(struct wb *wb, int fn, int sz, int m);
 288
 289 /* character translation (.tr) */
 290 void cmap_add(char *c1, char *c2);
 291 char *cmap_map(char *c);
 292 /* character definition (.char) */
 293 char *cdef_map(char *c, int fn);
 294 int cdef_expand(struct wb *wb, char *c, int fn);
 295
 296 /* hyphenation flags */
 297 #define HY_LAST         0x02    /* do not hyphenate last lines */
 298 #define HY_FINAL2       0x04    /* do not hyphenate the final two characters */
 299 #define HY_FIRST2       0x08    /* do not hyphenate the first two characters */
 300
 301 void hyphenate(char *hyphs, char *word, int flg);
 302
 303 /* adjustment types */
 304 #define AD_C            0       /* center */
 305 #define AD_L            1       /* adjust left margin (flag) */
 306 #define AD_R            2       /* adjust right margin (flag) */
 307 #define AD_B            3       /* adjust both margin (mask) */
 308 #define AD_P            4       /* paragraph-at-once adjustment (flag) */
 309
 310 /* line formatting */
 311 struct fmt *fmt_alloc(void);
 312 void fmt_free(struct fmt *fmt);
 313 int fmt_wid(struct fmt *fmt);
 314 void fmt_space(struct fmt *fmt);
 315 void fmt_suppressnl(struct fmt *fmt);
 316 int fmt_word(struct fmt *fmt, struct wb *wb);
 317 int fmt_newline(struct fmt *fmt);
 318 int fmt_fillreq(struct fmt *f);
 319 int fmt_br(struct fmt *fmt);
 320 int fmt_fill(struct fmt *fmt);
 321 int fmt_morelines(struct fmt *fmt);
 322 int fmt_morewords(struct fmt *fmt);
 323 int fmt_nextline(struct fmt *fmt, struct sbuf *sbuf, int *w,
 324                 int *li, int *ll, int *els_neg, int *els_pos);
 325
 326 /* rendering */
 327 int render(void);                               /* the main loop */
 328 int ren_parse(struct wb *wb, char *c);
 329 int ren_char(struct wb *wb, int (*next)(void), void (*back)(int));
 330 int ren_wid(int (*next)(void), void (*back)(int));
 331 void ren_tl(int (*next)(void), void (*back)(int));
 332 void ren_hline(struct wb *wb, int l, char *c);  /* horizontal line */
 333 void ren_hlcmd(struct wb *wb, char *arg);       /* \l */
 334 void ren_vlcmd(struct wb *wb, char *arg);       /* \L */
 335 void ren_bcmd(struct wb *wb, char *arg);        /* \b */
 336 void ren_ocmd(struct wb *wb, char *arg);        /* \o */
 337 void ren_dcmd(struct wb *wb, char *arg);        /* \D */
 338
 339 /* out.c */
 340 void out_line(char *s);                         /* output rendered line */
 341 void out(char *s, ...);                         /* output troff cmd */
 342
 343 /* troff commands */
 344 void tr_ab(char **args);
 345 void tr_bp(char **args);
 346 void tr_br(char **args);
 347 void tr_ce(char **args);
 348 void tr_ch(char **args);
 349 void tr_cl(char **args);
 350 void tr_di(char **args);
 351 void tr_divbeg(char **args);
 352 void tr_divend(char **args);
 353 void tr_dt(char **args);
 354 void tr_em(char **args);
 355 void tr_ev(char **args);
 356 void tr_fc(char **args);
 357 void tr_fi(char **args);
 358 void tr_fp(char **args);
 359 void tr_fspecial(char **args);
 360 void tr_ft(char **args);
 361 void tr_hpf(char **args);
 362 void tr_hpfa(char **args);
 363 void tr_hw(char **args);
 364 void tr_in(char **args);
 365 void tr_ll(char **args);
 366 void tr_mk(char **args);
 367 void tr_ne(char **args);
 368 void tr_nf(char **args);
 369 void tr_ns(char **args);
 370 void tr_os(char **args);
 371 void tr_pn(char **args);
 372 void tr_ps(char **args);
 373 void tr_rs(char **args);
 374 void tr_rt(char **args);
 375 void tr_sp(char **args);
 376 void tr_sv(char **args);
 377 void tr_ta(char **args);
 378 void tr_ti(char **args);
 379 void tr_wh(char **args);
 380 void tr_popren(char **args);
 381
 382 void tr_init(void);
 383 int tr_readargs(char **args, struct sbuf *sbuf,
 384                 int (*next)(void), void (*back)(int));
 385
 386 /* helpers */
 387 void errmsg(char *msg, ...);
 388 void errdie(char *msg);
 389 int utf8len(int c);
 390 int utf8next(char *s, int (*next)(void));
 391 int utf8read(char **s, char *d);
 392 int utf8one(char *s);
 393 int charnext(char *c, int (*next)(void), void (*back)(int));
 394 int charread(char **s, char *c);
 395 int charnext_delim(char *c, int (*next)(void), void (*back)(int), char *delim);
 396 int charread_delim(char **s, char *c, char *delim);
 397 void charnext_str(char *d, char *c);
 398 void argnext(char *d, int cmd, int (*next)(void), void (*back)(int));
 399 void argread(char **sp, char *d, int cmd);
 400 int escread(char **s, char *d);
 401 /* string streams; nested next()/back() interface for string buffers */
 402 void sstr_push(char *s);
 403 char *sstr_pop(void);
 404 int sstr_next(void);
 405 void sstr_back(int c);
 406
 407 /* internal commands */
 408 #define TR_DIVBEG       "\07<"  /* diversion begins */
 409 #define TR_DIVEND       "\07>"  /* diversion ends */
 410 #define TR_POPREN       "\07P"  /* exit render_rec() */
 411
 412 /* mapping register, macro and environment names to indices */
 413 #define NREGS           4096    /* maximum number of mapped names */
 414 #define DOTMAP(c2)      (c2)    /* optimized mapping for ".x" names */
 415
 416 int map(char *s);               /* map name s to an index */
 417 char *map_name(int id);         /* return the name mapped to id */
 418
 419 /* colors */
 420 #define CLR_R(c)                (((c) >> 16) & 0xff)
 421 #define CLR_G(c)                (((c) >> 8) & 0xff)
 422 #define CLR_B(c)                ((c) & 0xff)
 423 #define CLR_RGB(r, g, b)        (((r) << 16) | ((g) << 8) | (b))
 424
 425 char *clr_str(int c);
 426 int clr_get(char *s);
 427
 428 /* builtin number registers; n_X for .X register */
 429 #define n_a             (*nreg(DOTMAP('a')))
 430 #define n_cp            (*nreg(DOTMAP('C')))
 431 #define n_d             (*nreg(DOTMAP('d')))
 432 #define n_f             (*nreg(DOTMAP('f')))
 433 #define n_h             (*nreg(DOTMAP('h')))
 434 #define n_i             (*nreg(DOTMAP('i')))
 435 #define n_it            (*nreg(map(".it")))     /* .it trap macro */
 436 #define n_itn           (*nreg(map(".itn")))    /* .it lines left */
 437 #define n_j             (*nreg(DOTMAP('j')))
 438 #define n_l             (*nreg(DOTMAP('l')))
 439 #define n_L             (*nreg(DOTMAP('L')))
 440 #define n_n             (*nreg(DOTMAP('n')))
 441 #define n_nI            (*nreg(map(".nI")))     /* i for .nm */
 442 #define n_nm            (*nreg(map(".nm")))     /* .nm enabled */
 443 #define n_nM            (*nreg(map(".nM")))     /* m for .nm */
 444 #define n_nn            (*nreg(map(".nn")))     /* remaining .nn */
 445 #define n_nS            (*nreg(map(".nS")))     /* s for .nm */
 446 #define n_m             (*nreg(DOTMAP('m')))
 447 #define n_mc            (*nreg(map(".mc")))     /* .mc enabled */
 448 #define n_mcn           (*nreg(map(".mcn")))    /* .mc distance */
 449 #define n_o             (*nreg(DOTMAP('o')))
 450 #define n_p             (*nreg(DOTMAP('p')))
 451 #define n_s             (*nreg(DOTMAP('s')))
 452 #define n_u             (*nreg(DOTMAP('u')))
 453 #define n_v             (*nreg(DOTMAP('v')))
 454 #define n_ct            (*nreg(map("ct")))
 455 #define n_dl            (*nreg(map("dl")))
 456 #define n_dn            (*nreg(map("dn")))
 457 #define n_ln            (*nreg(map("ln")))
 458 #define n_nl            (*nreg(map("nl")))
 459 #define n_sb            (*nreg(map("sb")))
 460 #define n_st            (*nreg(map("st")))
 461 #define n_pg            (*nreg(map("%")))       /* % */
 462 #define n_lb            (*nreg(map(".b0")))     /* input line beg */
 463 #define n_ce            (*nreg(map(".ce")))     /* .ce remaining */
 464 #define n_f0            (*nreg(map(".f0")))     /* last .f */
 465 #define n_lg            (*nreg(map(".lg")))     /* .lg mode */
 466 #define n_hy            (*nreg(map(".hy")))     /* .hy mode */
 467 #define n_hyp           (*nreg(map(".hyp")))    /* hyphenation penalty  */
 468 #define n_i0            (*nreg(map(".i0")))     /* last .i */
 469 #define n_ti            (*nreg(map(".ti")))     /* pending .ti */
 470 #define n_kn            (*nreg(map(".kern")))   /* .kn mode */
 471 #define n_l0            (*nreg(map(".l0")))     /* last .l */
 472 #define n_L0            (*nreg(map(".L0")))     /* last .L */
 473 #define n_m0            (*nreg(map(".m0")))     /* last .m */
 474 #define n_mk            (*nreg(map(".mk")))     /* .mk internal register */
 475 #define n_na            (*nreg(map(".na")))     /* .na mode */
 476 #define n_ns            (*nreg(map(".ns")))     /* .ns mode */
 477 #define n_o0            (*nreg(map(".o0")))     /* last .o */
 478 #define n_ss            (*nreg(map(".ss")))     /* word space (.ss) */
 479 #define n_sss           (*nreg(map(".sss")))    /* sentence space (.ss) */
 480 #define n_ssh           (*nreg(map(".ssh")))    /* word space compression (.ssh) */
 481 #define n_s0            (*nreg(map(".s0")))     /* last .s */
 482 #define n_sv            (*nreg(map(".sv")))     /* .sv value */
 483 #define n_lt            (*nreg(map(".lt")))     /* .lt value */
 484 #define n_t0            (*nreg(map(".lt0")))    /* previous .lt value */
 485 #define n_v0            (*nreg(map(".v0")))     /* last .v */
 486 #define n_llx           (*nreg(map("bbllx")))   /* \w bounding box */
 487 #define n_lly           (*nreg(map("bblly")))   /* \w bounding box */
 488 #define n_urx           (*nreg(map("bburx")))   /* \w bounding box */
 489 #define n_ury           (*nreg(map("bbury")))   /* \w bounding box */
 490
 491 /* functions for implementing read-only registers */
 492 int f_nexttrap(void);   /* .t */
 493 int f_divreg(void);     /* .z */
 494 int f_hpos(void);       /* .k */