libguile/gc.h

   1 /* classes: h_files */
   2
   3 #ifndef GCH
   4 #define GCH
   5 /* Copyright (C) 1995, 96, 98, 99, 2000 Free Software Foundation, Inc.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2, or (at your option)
  10  * any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this software; see the file COPYING.  If not, write to
  19  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  20  * Boston, MA 02111-1307 USA
  21  *
  22  * As a special exception, the Free Software Foundation gives permission
  23  * for additional uses of the text contained in its release of GUILE.
  24  *
  25  * The exception is that, if you link the GUILE library with other files
  26  * to produce an executable, this does not by itself cause the
  27  * resulting executable to be covered by the GNU General Public License.
  28  * Your use of that executable is in no way restricted on account of
  29  * linking the GUILE library code into it.
  30  *
  31  * This exception does not however invalidate any other reasons why
  32  * the executable file might be covered by the GNU General Public License.
  33  *
  34  * This exception applies only to the code released by the
  35  * Free Software Foundation under the name GUILE.  If you copy
  36  * code from other Free Software Foundation releases into a copy of
  37  * GUILE, as the General Public License permits, the exception does
  38  * not apply to the code that you add in this way.  To avoid misleading
  39  * anyone as to the status of such modified files, you must delete
  40  * this exception notice from them.
  41  *
  42  * If you write modifications of your own for GUILE, it is your choice
  43  * whether to permit this exception to apply to your modifications.
  44  * If you do not wish that, delete this exception notice.  */
  45
  46 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  47    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  48 \f
  49
  50 #include "libguile/__scm.h"
  51
  52 #include "libguile/hooks.h"
  53
  54 \f
  55
  56 typedef struct scm_cell
  57 {
  58   scm_bits_t word_0;
  59   scm_bits_t word_1;
  60 } scm_cell;
  61
  62
  63 /* SCM_CELLPTR is a pointer to a cons cell which may be compared or
  64  * differenced.
  65  */
  66 typedef scm_cell * SCM_CELLPTR;
  67
  68
  69 /* Cray machines have pointers that are incremented once for each word,
  70  * rather than each byte, the 3 most significant bits encode the byte
  71  * within the word.  The following macros deal with this by storing the
  72  * native Cray pointers like the ones that looks like scm expects.  This
  73  * is done for any pointers that might appear in the car of a scm_cell,
  74  * pointers to scm_vector elts, functions, &c are not munged.
  75  */
  76 #ifdef _UNICOS
  77 #  define SCM2PTR(x) ((SCM_CELLPTR) (SCM_UNPACK (x) >> 3))
  78 #  define PTR2SCM(x) (SCM_PACK (((scm_bits_t) (x)) << 3))
  79 #else
  80 #  define SCM2PTR(x) ((SCM_CELLPTR) (SCM_UNPACK (x)))
  81 #  define PTR2SCM(x) (SCM_PACK ((scm_bits_t) (x)))
  82 #endif /* def _UNICOS */
  83
  84 /* This mess was copied from the GNU getpagesize.h.  */
  85
  86 #ifndef HAVE_GETPAGESIZE
  87
  88 /* Assume that all systems that can run configure have sys/param.h.  */
  89 # ifndef HAVE_SYS_PARAM_H
  90 #  define HAVE_SYS_PARAM_H 1
  91 # endif
  92
  93 # ifdef _SC_PAGESIZE
  94 #  define getpagesize() sysconf(_SC_PAGESIZE)
  95 # else /* no _SC_PAGESIZE */
  96 #  ifdef HAVE_SYS_PARAM_H
  97 #   include <sys/param.h>
  98 #   ifdef EXEC_PAGESIZE
  99 #    define getpagesize() EXEC_PAGESIZE
 100 #   else /* no EXEC_PAGESIZE */
 101 #    ifdef NBPG
 102 #     define getpagesize() NBPG * CLSIZE
 103 #     ifndef CLSIZE
 104 #      define CLSIZE 1
 105 #     endif /* no CLSIZE */
 106 #    else /* no NBPG */
 107 #     ifdef NBPC
 108 #      define getpagesize() NBPC
 109 #     else /* no NBPC */
 110 #      ifdef PAGESIZE
 111 #       define getpagesize() PAGESIZE
 112 #      endif /* PAGESIZE */
 113 #     endif /* no NBPC */
 114 #    endif /* no NBPG */
 115 #   endif /* no EXEC_PAGESIZE */
 116 #  else /* no HAVE_SYS_PARAM_H */
 117 #   define getpagesize() 8192   /* punt totally */
 118 #  endif /* no HAVE_SYS_PARAM_H */
 119 # endif /* no _SC_PAGESIZE */
 120
 121 #endif /* no HAVE_GETPAGESIZE */
 122
 123 #define SCM_GC_CARD_N_HEADER_CELLS 1
 124 #define SCM_GC_CARD_N_CELLS        (8 * sizeof (scm_cell) * 4)
 125
 126 #define SCM_GC_CARD_SIZE           (SCM_GC_CARD_N_CELLS * sizeof (scm_cell))
 127 #define SCM_GC_CARD_N_DATA_CELLS   (SCM_GC_CARD_N_CELLS - SCM_GC_CARD_N_HEADER_CELLS)
 128
 129 #define SCM_GC_CARD_BVEC_SIZE_IN_LIMBS \
 130     ((SCM_GC_CARD_N_CELLS + SCM_C_BVEC_LIMB_BITS - 1) / SCM_C_BVEC_LIMB_BITS)
 131
 132 #define SCM_GC_IN_CARD_HEADERP(x) \
 133     SCM_PTR_LT ((scm_cell *) (x), SCM_GC_CELL_CARD (x) + SCM_GC_CARD_N_HEADER_CELLS)
 134
 135 #define SCM_GC_CARD_BVEC(card)  ((scm_c_bvec_limb_t *) ((card)->word_0))
 136
 137 #define SCM_GC_GET_CARD_FLAGS(card) ((long) ((card)->word_1))
 138 #define SCM_GC_SET_CARD_FLAGS(card, flags) (SCM_GC_GET_CARD_FLAGS (card) = (flags))
 139 #define SCM_GC_CLR_CARD_FLAGS(card) (SCM_GC_GET_CARD_FLAGS (card) = 0L)
 140
 141 #define SCM_GC_GET_CARD_FLAG(card, shift) (SCM_GC_GET_CARD_FLAGS (card) & (1L << (shift)))
 142 #define SCM_GC_SET_CARD_FLAG(card, shift) (SCM_GC_GET_CARD_FLAGS (card) |= (1L << (shift)))
 143 #define SCM_GC_CLR_CARD_FLAG(card, shift) (SCM_GC_GET_CARD_FLAGS (card) &= ~(1L << (shift)))
 144
 145 #define SCM_GC_CARDF_DOUBLECELL 0
 146
 147 #define SCM_GC_CARD_DOUBLECELLP(card)    SCM_GC_GET_CARD_FLAG (card, SCM_GC_CARDF_DOUBLECELL)
 148 #define SCM_GC_SET_CARD_DOUBLECELL(card) SCM_GC_SET_CARD_FLAG (card, SCM_GC_CARDF_DOUBLECELL)
 149
 150 /* card addressing. for efficiency, cards are *always* aligned to
 151    SCM_GC_CARD_SIZE. */
 152
 153 #define SCM_GC_CARD_SIZE_MASK  (SCM_GC_CARD_SIZE - 1)
 154 #define SCM_GC_CARD_ADDR_MASK  (~SCM_GC_CARD_SIZE_MASK)
 155
 156 #define SCM_GC_CELL_CARD(x)    ((SCM_CELLPTR) ((long) (x) & SCM_GC_CARD_ADDR_MASK))
 157 #define SCM_GC_CELL_SPAN(x)    ((SCM_GC_CARD_DOUBLECELLP (SCM_GC_CELL_CARD (x))) ? 2 : 1)
 158 #define SCM_GC_CELL_OFFSET(x)  (((long) (x) & SCM_GC_CARD_SIZE_MASK) >> SCM_CELL_SIZE_SHIFT)
 159 #define SCM_GC_CELL_BVEC(x)    SCM_GC_CARD_BVEC (SCM_GC_CELL_CARD (x))
 160 #define SCM_GC_CELL_GET_BIT(x) SCM_C_BVEC_GET (SCM_GC_CELL_BVEC (x), SCM_GC_CELL_OFFSET (x))
 161 #define SCM_GC_CELL_SET_BIT(x) SCM_C_BVEC_SET (SCM_GC_CELL_BVEC (x), SCM_GC_CELL_OFFSET (x))
 162 #define SCM_GC_CELL_CLR_BIT(x) SCM_C_BVEC_CLR (SCM_GC_CELL_BVEC (x), SCM_GC_CELL_OFFSET (x))
 163
 164 #define SCM_GC_CARD_UP(x)      SCM_GC_CELL_CARD ((char *) (x) + SCM_GC_CARD_SIZE - 1)
 165 #define SCM_GC_CARD_DOWN       SCM_GC_CELL_CARD
 166
 167 /* low level bit banging aids */
 168
 169 typedef unsigned long scm_c_bvec_limb_t;
 170
 171 #if (SIZEOF_LONG == 8)
 172 #       define SCM_C_BVEC_LIMB_BITS    64
 173 #       define SCM_C_BVEC_OFFSET_SHIFT 6
 174 #       define SCM_C_BVEC_POS_MASK     63
 175 #       define SCM_CELL_SIZE_SHIFT     4
 176 #else
 177 #       define SCM_C_BVEC_LIMB_BITS    32
 178 #       define SCM_C_BVEC_OFFSET_SHIFT 5
 179 #       define SCM_C_BVEC_POS_MASK     31
 180 #       define SCM_CELL_SIZE_SHIFT     3
 181 #endif
 182
 183 #define SCM_C_BVEC_OFFSET(pos) (pos >> SCM_C_BVEC_OFFSET_SHIFT)
 184
 185 #define SCM_C_BVEC_GET(bvec, pos) (bvec[SCM_C_BVEC_OFFSET (pos)] & (1L << (pos & SCM_C_BVEC_POS_MASK)))
 186 #define SCM_C_BVEC_SET(bvec, pos) (bvec[SCM_C_BVEC_OFFSET (pos)] |= (1L << (pos & SCM_C_BVEC_POS_MASK)))
 187 #define SCM_C_BVEC_CLR(bvec, pos) (bvec[SCM_C_BVEC_OFFSET (pos)] &= ~(1L << (pos & SCM_C_BVEC_POS_MASK)))
 188
 189 #define SCM_C_BVEC_BITS2BYTES(bits) \
 190     (sizeof (scm_c_bvec_limb_t) * ((((bits) & SCM_C_BVEC_POS_MASK) ? 1L : 0L) + SCM_C_BVEC_OFFSET (bits)))
 191
 192 #define SCM_C_BVEC_SET_BYTES(bvec, bytes)   (memset (bvec, 0xff, bytes))
 193 #define SCM_C_BVEC_SET_ALL_BITS(bvec, bits) SCM_C_BVEC_SET_BYTES (bvec, SCM_C_BVEC_BITS2BYTES (bits))
 194
 195 #define SCM_C_BVEC_CLR_BYTES(bvec, bytes)   (memset (bvec, 0, bytes))
 196 #define SCM_C_BVEC_CLR_ALL_BITS(bvec, bits) SCM_C_BVEC_CLR_BYTES (bvec, SCM_C_BVEC_BITS2BYTES (bits))
 197
 198 /* testing and changing GC marks */
 199
 200 #define SCM_GCMARKP(x)   SCM_GC_CELL_GET_BIT (x)
 201 #define SCM_SETGCMARK(x) SCM_GC_CELL_SET_BIT (x)
 202 #define SCM_CLRGCMARK(x) SCM_GC_CELL_CLR_BIT (x)
 203
 204 /* compatibility stuff: */
 205
 206 #define SCM_GC8MARKP(x)   SCM_GCMARKP (x)
 207 #define SCM_SETGC8MARK(x) SCM_SETGCMARK (x)
 208 #define SCM_CLRGC8MARK(x) SCM_CLRGCMARK (x)
 209
 210 #define SCM_GCTYP16(x) SCM_TYP16 (x)
 211 #define SCM_GCCDR(x)   SCM_CDR (x)
 212
 213 /* Low level cell data accessing macros:
 214  */
 215
 216 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 217 #  define SCM_VALIDATE_CELL(cell, expr) (scm_assert_cell_valid (cell), (expr))
 218 #else
 219 #  define SCM_VALIDATE_CELL(cell, expr) expr
 220 #endif
 221
 222 #define SCM_CELL_WORD(x, n) \
 223   SCM_VALIDATE_CELL ((x), ((const scm_bits_t *) SCM2PTR (x)) [n])
 224 #define SCM_CELL_WORD_0(x) SCM_CELL_WORD (x, 0)
 225 #define SCM_CELL_WORD_1(x) SCM_CELL_WORD (x, 1)
 226 #define SCM_CELL_WORD_2(x) SCM_CELL_WORD (x, 2)
 227 #define SCM_CELL_WORD_3(x) SCM_CELL_WORD (x, 3)
 228
 229 #define SCM_CELL_OBJECT(x, n) \
 230   SCM_VALIDATE_CELL ((x), SCM_PACK (((const scm_bits_t *) SCM2PTR (x)) [n]))
 231 #define SCM_CELL_OBJECT_0(x) SCM_CELL_OBJECT (x, 0)
 232 #define SCM_CELL_OBJECT_1(x) SCM_CELL_OBJECT (x, 1)
 233 #define SCM_CELL_OBJECT_2(x) SCM_CELL_OBJECT (x, 2)
 234 #define SCM_CELL_OBJECT_3(x) SCM_CELL_OBJECT (x, 3)
 235
 236 #define SCM_SET_CELL_WORD(x, n, v) \
 237   SCM_VALIDATE_CELL ((x), ((scm_bits_t *) SCM2PTR (x)) [n] = (scm_bits_t) (v))
 238 #define SCM_SET_CELL_WORD_0(x, v) SCM_SET_CELL_WORD (x, 0, v)
 239 #define SCM_SET_CELL_WORD_1(x, v) SCM_SET_CELL_WORD (x, 1, v)
 240 #define SCM_SET_CELL_WORD_2(x, v) SCM_SET_CELL_WORD (x, 2, v)
 241 #define SCM_SET_CELL_WORD_3(x, v) SCM_SET_CELL_WORD (x, 3, v)
 242
 243 #define SCM_SET_CELL_OBJECT(x, n, v) \
 244   SCM_VALIDATE_CELL ((x), ((scm_bits_t *) SCM2PTR (x)) [n] = SCM_UNPACK (v))
 245 #define SCM_SET_CELL_OBJECT_0(x, v) SCM_SET_CELL_OBJECT (x, 0, v)
 246 #define SCM_SET_CELL_OBJECT_1(x, v) SCM_SET_CELL_OBJECT (x, 1, v)
 247 #define SCM_SET_CELL_OBJECT_2(x, v) SCM_SET_CELL_OBJECT (x, 2, v)
 248 #define SCM_SET_CELL_OBJECT_3(x, v) SCM_SET_CELL_OBJECT (x, 3, v)
 249
 250 #define SCM_CELL_TYPE(x) SCM_CELL_WORD_0 (x)
 251 #define SCM_SET_CELL_TYPE(x, t) SCM_SET_CELL_WORD_0 (x, t)
 252
 253 #define SCM_SETAND_CAR(x, y) \
 254   (SCM_SETCAR ((x), SCM_PACK (SCM_UNPACK (SCM_CAR (x)) & (y))))
 255 #define SCM_SETAND_CDR(x, y)\
 256   (SCM_SETCDR ((x), SCM_PACK (SCM_UNPACK (SCM_CDR (x)) & (y))))
 257 #define SCM_SETOR_CAR(x, y)\
 258   (SCM_SETCAR ((x), SCM_PACK (SCM_UNPACK (SCM_CAR (x)) | (y))))
 259 #define SCM_SETOR_CDR(x, y)\
 260   (SCM_SETCDR ((x), SCM_PACK (SCM_UNPACK (SCM_CDR (x)) | (y))))
 261
 262 #define SCM_CELL_WORD_LOC(x, n) ((scm_bits_t *) & SCM_CELL_WORD (x, n))
 263 #define SCM_CARLOC(x) ((SCM *) SCM_CELL_WORD_LOC ((x), 0))
 264 #define SCM_CDRLOC(x) ((SCM *) SCM_CELL_WORD_LOC ((x), 1))
 265
 266
 267 /* SCM_PTR_LT and friends define how to compare two SCM_CELLPTRs (which may
 268  * point to cells in different heap segments).
 269  */
 270 #define SCM_PTR_LT(x, y) ((x) < (y))
 271 #define SCM_PTR_GT(x, y) (SCM_PTR_LT (y, x))
 272 #define SCM_PTR_LE(x, y) (!SCM_PTR_GT (x, y))
 273 #define SCM_PTR_GE(x, y) (!SCM_PTR_LT (x, y))
 274
 275
 276 /* Freelists consist of linked cells where the type entry holds the value
 277  * scm_tc_free_cell and the second entry holds a pointer to the next cell of
 278  * the freelist.  Due to this structure, freelist cells are not cons cells
 279  * and thus may not be accessed using SCM_CAR and SCM_CDR.
 280  */
 281
 282 #define SCM_FREE_CELL_P(x) \
 283   (!SCM_IMP (x) && (* (const scm_bits_t *) SCM2PTR (x) == scm_tc_free_cell))
 284 #define SCM_FREE_CELL_CDR(x) \
 285   (SCM_PACK (((const scm_bits_t *) SCM2PTR (x)) [1]))
 286 #define SCM_SET_FREE_CELL_TYPE(x, v) \
 287   (((scm_bits_t *) SCM2PTR (x)) [0] = (v))
 288 #define SCM_SET_FREE_CELL_CDR(x, v) \
 289   (((scm_bits_t *) SCM2PTR (x)) [1] = SCM_UNPACK (v))
 290
 291 /* the allocated thing:  The car of new cells is set to
 292    scm_tc16_allocated to avoid the fragile state of newcells wrt the
 293    gc.  If it stays as a freecell, any allocation afterwards could
 294    cause the cell to go back on the freelist, which will bite you
 295    sometime afterwards. */
 296
 297 #ifdef GUILE_DEBUG_FREELIST
 298 #define SCM_NEWCELL(_into) do { _into = scm_debug_newcell (); } while (0)
 299 #define SCM_NEWCELL2(_into) do { _into = scm_debug_newcell2 (); } while (0)
 300 #else
 301 /* When we introduce POSIX threads support, every thread will have
 302    a freelist of its own.  Then it won't any longer be necessary to
 303    initialize cells with scm_tc16_allocated.  */
 304 #define SCM_NEWCELL(_into) \
 305         do { \
 306           if (SCM_IMP (scm_freelist)) \
 307              _into = scm_gc_for_newcell (&scm_master_freelist, \
 308                                          &scm_freelist); \
 309           else \
 310             { \
 311                _into = scm_freelist; \
 312                scm_freelist = SCM_FREE_CELL_CDR (scm_freelist); \
 313                SCM_SET_FREE_CELL_TYPE (_into, scm_tc16_allocated); \
 314             } \
 315         } while(0)
 316 #define SCM_NEWCELL2(_into) \
 317         do { \
 318           if (SCM_IMP (scm_freelist2)) \
 319              _into = scm_gc_for_newcell (&scm_master_freelist2, \
 320                                          &scm_freelist2); \
 321           else \
 322             { \
 323                _into = scm_freelist2; \
 324                scm_freelist2 = SCM_FREE_CELL_CDR (scm_freelist2); \
 325                SCM_SET_FREE_CELL_TYPE (_into, scm_tc16_allocated); \
 326             } \
 327         } while(0)
 328 #endif
 329
 330
 331 #define SCM_FREEP(x) (SCM_FREE_CELL_P (x))
 332 #define SCM_NFREEP(x) (!SCM_FREEP (x))
 333
 334 #define SCM_MARKEDP    SCM_GCMARKP
 335 #define SCM_NMARKEDP(x) (!SCM_MARKEDP (x))
 336
 337 extern struct scm_heap_seg_data_t *scm_heap_table;
 338 extern int scm_n_heap_segs;
 339 extern int scm_block_gc;
 340 extern int scm_gc_heap_lock;
 341 extern unsigned int scm_gc_running_p;
 342 \f
 343
 344 extern int scm_default_init_heap_size_1;
 345 extern int scm_default_min_yield_1;
 346 extern int scm_default_init_heap_size_2;
 347 extern int scm_default_min_yield_2;
 348 extern int scm_default_max_segment_size;
 349
 350 extern scm_sizet scm_max_segment_size;
 351 extern SCM_CELLPTR scm_heap_org;
 352 extern SCM scm_freelist;
 353 extern struct scm_freelist_t scm_master_freelist;
 354 extern SCM scm_freelist2;
 355 extern struct scm_freelist_t scm_master_freelist2;
 356 extern unsigned long scm_gc_cells_collected;
 357 extern unsigned long scm_gc_yield;
 358 extern unsigned long scm_gc_malloc_collected;
 359 extern unsigned long scm_gc_ports_collected;
 360 extern unsigned long scm_cells_allocated;
 361 extern long scm_mallocated;
 362 extern unsigned long scm_mtrigger;
 363
 364 extern SCM scm_after_gc_hook;
 365
 366 extern scm_c_hook_t scm_before_gc_c_hook;
 367 extern scm_c_hook_t scm_before_mark_c_hook;
 368 extern scm_c_hook_t scm_before_sweep_c_hook;
 369 extern scm_c_hook_t scm_after_sweep_c_hook;
 370 extern scm_c_hook_t scm_after_gc_c_hook;
 371
 372 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 373 extern void scm_assert_cell_valid (SCM);
 374 extern unsigned int scm_debug_cell_accesses_p;
 375 extern SCM scm_set_debug_cell_accesses_x (SCM flag);
 376 #endif
 377
 378 #if defined (GUILE_DEBUG) || defined (GUILE_DEBUG_FREELIST)
 379 extern SCM scm_map_free_list (void);
 380 extern SCM scm_free_list_length (void);
 381 #endif
 382 #ifdef GUILE_DEBUG_FREELIST
 383 extern SCM scm_debug_newcell (void);
 384 extern SCM scm_debug_newcell2 (void);
 385 extern SCM scm_gc_set_debug_check_freelist_x (SCM flag);
 386 #endif
 387
 388 \f
 389
 390 extern SCM scm_object_address (SCM obj);
 391 extern SCM scm_unhash_name (SCM name);
 392 extern SCM scm_gc_stats (void);
 393 extern SCM scm_gc (void);
 394 extern void scm_gc_for_alloc (struct scm_freelist_t *freelist);
 395 extern SCM scm_gc_for_newcell (struct scm_freelist_t *master, SCM *freelist);
 396 #if 0
 397 extern void scm_alloc_cluster (struct scm_freelist_t *master);
 398 #endif
 399 extern void scm_igc (const char *what);
 400 extern void scm_gc_mark (SCM p);
 401 extern void scm_mark_locations (SCM_STACKITEM x[], scm_sizet n);
 402 extern int scm_cellp (SCM value);
 403 extern void scm_gc_sweep (void);
 404 extern void * scm_must_malloc (scm_sizet len, const char *what);
 405 extern void * scm_must_realloc (void *where,
 406                                 scm_sizet olen, scm_sizet len,
 407                                 const char *what);
 408 extern void scm_done_malloc (long size);
 409 extern void scm_done_free (long size);
 410 extern void scm_must_free (void *obj);
 411 extern void scm_remember (SCM * ptr);
 412 extern SCM scm_return_first (SCM elt, ...);
 413 extern int scm_return_first_int (int x, ...);
 414 extern SCM scm_permanent_object (SCM obj);
 415 extern SCM scm_protect_object (SCM obj);
 416 extern SCM scm_unprotect_object (SCM obj);
 417 extern int scm_init_storage (scm_sizet init_heap_size, int trig,
 418                              scm_sizet init_heap2_size, int trig2,
 419                              scm_sizet max_segment_size);
 420 extern void scm_init_gc (void);
 421 #endif  /* GCH */
 422
 423 /*
 424   Local Variables:
 425   c-file-style: "gnu"
 426   End:
 427 */