libguile/continuations.c

   1 /* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19
  20 \f
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include "libguile/_scm.h"
  26
  27 #include <string.h>
  28 #include <stdio.h>
  29
  30 #include "libguile/async.h"
  31 #include "libguile/debug.h"
  32 #include "libguile/root.h"
  33 #include "libguile/stackchk.h"
  34 #include "libguile/smob.h"
  35 #include "libguile/ports.h"
  36 #include "libguile/dynwind.h"
  37 #include "libguile/eval.h"
  38 #include "libguile/vm.h"
  39 #include "libguile/instructions.h"
  40
  41 #include "libguile/validate.h"
  42 #include "libguile/continuations.h"
  43
  44 \f
  45
  46 static scm_t_bits tc16_continuation;
  47 #define SCM_CONTREGSP(x)        SCM_TYP16_PREDICATE (tc16_continuation, x)
  48
  49 #define SCM_CONTREGS(x)         ((scm_t_contregs *) SCM_SMOB_DATA_1 (x))
  50
  51 #define SCM_CONTINUATION_LENGTH(x) (SCM_CONTREGS (x)->num_stack_items)
  52 #define SCM_SET_CONTINUATION_LENGTH(x, n)\
  53    (SCM_CONTREGS (x)->num_stack_items = (n))
  54 #define SCM_JMPBUF(x)            ((SCM_CONTREGS (x))->jmpbuf)
  55 #define SCM_DYNENV(x)            ((SCM_CONTREGS (x))->dynenv)
  56 #define SCM_CONTINUATION_ROOT(x) ((SCM_CONTREGS (x))->root)
  57 #define SCM_DFRAME(x)            ((SCM_CONTREGS (x))->dframe)
  58
  59 \f
  60
  61 /* scm_i_make_continuation will return a procedure whose objcode contains an
  62    instruction to reinstate the continuation. Here, as in gsubr.c and smob.c, we
  63    define the form of that trampoline function.
  64  */
  65
  66 #ifdef WORDS_BIGENDIAN
  67 #define OBJCODE_HEADER(main,meta) 0, 0, 0, main, 0, 0, 0, meta+8
  68 #define META_HEADER(meta)         0, 0, 0, meta, 0, 0, 0, 0
  69 #else
  70 #define OBJCODE_HEADER(main,meta) main, 0, 0, 0, meta+8, 0, 0, 0
  71 #define META_HEADER(meta)         meta, 0, 0, 0, 0,      0, 0, 0
  72 #endif
  73
  74 #define ALIGN_PTR(type,p,align) (type*)(ROUND_UP (((scm_t_bits)p), align))
  75
  76 #ifdef SCM_ALIGNED
  77 #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym)     \
  78 static const type sym[]
  79 #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym)  \
  80 static SCM_ALIGNED (alignment) const type sym[]
  81 #else
  82 #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym)     \
  83 static type *sym
  84 #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym)                  \
  85 SCM_SNARF_INIT(sym = scm_malloc_pointerless (sizeof(sym##__unaligned)); \
  86                memcpy (sym, sym##__unaligned, sizeof(sym##__unaligned));) \
  87 static type *sym = NULL;                                                \
  88 static const type sym##__unaligned[]
  89 #endif
  90
  91 #define STATIC_OBJCODE_TAG                                      \
  92   SCM_PACK (SCM_MAKE_OBJCODE_TAG (SCM_OBJCODE_TYPE_STATIC, 0))
  93
  94 #define SCM_STATIC_OBJCODE(sym)                                         \
  95   SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode);      \
  96   SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = {            \
  97     { STATIC_OBJCODE_TAG, SCM_PACK (sym##__bytecode) },                 \
  98     { SCM_BOOL_F, SCM_PACK (0) }                                        \
  99   };                                                                    \
 100   static const SCM sym = SCM_PACK (sym##__cells);                       \
 101   SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode)
 102
 103
 104 SCM_STATIC_OBJCODE (cont_objcode) = {
 105   /* This code is the same as in gsubr.c, except we use continuation_call
 106      instead of subr_call. */
 107   OBJCODE_HEADER (8, 19),
 108   /* leave args on the stack */
 109   /* 0 */ scm_op_object_ref, 0, /* push scm_t_contregs smob */
 110   /* 2 */ scm_op_continuation_call, /* and longjmp (whee) */
 111   /* 3 */ scm_op_nop, /* pad to 8 bytes */
 112   /* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop,
 113   /* 8 */
 114
 115   /* We could put some meta-info to say that this proc is a continuation. Not sure
 116      how to do that, though. */
 117   META_HEADER (19),
 118   /* 0 */ scm_op_make_eol, /* bindings */
 119   /* 1 */ scm_op_make_eol, /* sources */
 120   /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */
 121   /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */
 122   /* 7 */ scm_op_make_int8_0, /* 0 optionals */
 123   /* 8 */ scm_op_make_true, /* and a rest arg */
 124   /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */
 125   /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */
 126   /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */
 127   /* 18 */ scm_op_return /* and return */
 128   /* 19 */
 129 };
 130
 131
 132 SCM_STATIC_OBJCODE (call_cc_objcode) = {
 133   /* Before Scheme's call/cc is compiled, eval.c will use this hand-coded
 134      call/cc. */
 135   OBJCODE_HEADER (8, 17),
 136   /* 0 */ scm_op_assert_nargs_ee, 0, 1, /* assert that nargs==1 */
 137   /* 3 */ scm_op_local_ref, 0, /* push the proc */
 138   /* 5 */ scm_op_tail_call_cc, /* and call/cc */
 139   /* 6 */ scm_op_nop, scm_op_nop, /* pad to 8 bytes */
 140   /* 8 */
 141
 142   META_HEADER (17),
 143   /* 0 */ scm_op_make_eol, /* bindings */
 144   /* 1 */ scm_op_make_eol, /* sources */
 145   /* 2 */ scm_op_make_int8, 3, scm_op_make_int8, 6, /* arity: from ip 0 to ip 6 */
 146   /* 6 */ scm_op_make_int8_1, /* the arity is 0 required args */
 147   /* 7 */ scm_op_list, 0, 3, /* make a list of those 5 vals */
 148   /* 10 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */
 149   /* 13 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */
 150   /* 16 */ scm_op_return /* and return */
 151   /* 17 */
 152 };
 153
 154
 155 static SCM
 156 make_continuation_trampoline (SCM contregs)
 157 {
 158   SCM ret = scm_make_program (cont_objcode,
 159                               scm_c_make_vector (1, contregs),
 160                               SCM_BOOL_F);
 161   SCM_SET_CELL_WORD_0 (ret,
 162                        SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_CONTINUATION);
 163
 164   return ret;
 165 }
 166
 167
 168 /* {Continuations}
 169  */
 170
 171
 172 static int
 173 continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED)
 174 {
 175   scm_t_contregs *continuation = SCM_CONTREGS (obj);
 176
 177   scm_puts_unlocked ("#<continuation ", port);
 178   scm_intprint (continuation->num_stack_items, 10, port);
 179   scm_puts_unlocked (" @ ", port);
 180   scm_uintprint (SCM_SMOB_DATA_1 (obj), 16, port);
 181   scm_putc_unlocked ('>', port);
 182   return 1;
 183 }
 184
 185 /* James Clark came up with this neat one instruction fix for
 186  * continuations on the SPARC.  It flushes the register windows so
 187  * that all the state of the process is contained in the stack.
 188  */
 189
 190 #if defined (sparc) || defined (__sparc__) || defined (__sparc)
 191 # define SCM_FLUSH_REGISTER_WINDOWS asm("ta 3")
 192 #else
 193 # define SCM_FLUSH_REGISTER_WINDOWS /* empty */
 194 #endif
 195
 196 /* this may return more than once: the first time with the escape
 197    procedure, then subsequently with SCM_UNDEFINED (the vals already having been
 198    placed on the VM stack). */
 199 #define FUNC_NAME "scm_i_make_continuation"
 200 SCM
 201 scm_i_make_continuation (int *first, SCM vm, SCM vm_cont)
 202 {
 203   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 204   SCM cont;
 205   scm_t_contregs *continuation;
 206   long stack_size;
 207   SCM_STACKITEM * src;
 208
 209   SCM_FLUSH_REGISTER_WINDOWS;
 210   stack_size = scm_stack_size (thread->continuation_base);
 211   continuation = scm_gc_malloc (sizeof (scm_t_contregs)
 212                                 + (stack_size - 1) * sizeof (SCM_STACKITEM),
 213                                 "continuation");
 214   continuation->num_stack_items = stack_size;
 215   continuation->dynenv = scm_i_dynwinds ();
 216   continuation->root = thread->continuation_root;
 217   src = thread->continuation_base;
 218 #if ! SCM_STACK_GROWS_UP
 219   src -= stack_size;
 220 #endif
 221   continuation->offset = continuation->stack - src;
 222   memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size);
 223   continuation->vm = vm;
 224   continuation->vm_cont = vm_cont;
 225
 226   SCM_NEWSMOB (cont, tc16_continuation, continuation);
 227
 228   *first = !SCM_I_SETJMP (continuation->jmpbuf);
 229   if (*first)
 230     {
 231 #ifdef __ia64__
 232       continuation->backing_store_size =
 233         (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx)
 234         -
 235         (char *) thread->register_backing_store_base;
 236       continuation->backing_store = NULL;
 237       continuation->backing_store =
 238         scm_gc_malloc (continuation->backing_store_size,
 239                        "continuation backing store");
 240       memcpy (continuation->backing_store,
 241               (void *) thread->register_backing_store_base,
 242               continuation->backing_store_size);
 243 #endif /* __ia64__ */
 244       return make_continuation_trampoline (cont);
 245     }
 246   else
 247     return SCM_UNDEFINED;
 248 }
 249 #undef FUNC_NAME
 250
 251 SCM
 252 scm_i_call_with_current_continuation (SCM proc)
 253 {
 254   static SCM call_cc = SCM_BOOL_F;
 255
 256   if (scm_is_false (call_cc))
 257     call_cc = scm_make_program (call_cc_objcode, SCM_BOOL_F, SCM_BOOL_F);
 258
 259   return scm_call_1 (call_cc, proc);
 260 }
 261
 262 SCM
 263 scm_i_continuation_to_frame (SCM continuation)
 264 {
 265   SCM contregs;
 266   scm_t_contregs *cont;
 267
 268   contregs = scm_c_vector_ref (scm_program_objects (continuation), 0);
 269   cont = SCM_CONTREGS (contregs);
 270
 271   if (scm_is_true (cont->vm_cont))
 272     {
 273       struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont);
 274       return scm_c_make_frame (cont->vm_cont,
 275                                data->fp + data->reloc,
 276                                data->sp + data->reloc,
 277                                data->ra,
 278                                data->reloc);
 279     }
 280   else
 281     return SCM_BOOL_F;
 282 }
 283
 284 SCM
 285 scm_i_contregs_vm (SCM contregs)
 286 {
 287   return SCM_CONTREGS (contregs)->vm;
 288 }
 289
 290 SCM
 291 scm_i_contregs_vm_cont (SCM contregs)
 292 {
 293   return SCM_CONTREGS (contregs)->vm_cont;
 294 }
 295
 296
 297 /* {Apply}
 298  */
 299
 300 /* Invoking a continuation proceeds as follows:
 301  *
 302  * - the stack is made large enough for the called continuation
 303  * - the old windchain is unwound down to the branching point
 304  * - the continuation stack is copied into place
 305  * - the windchain is rewound up to the continuation's context
 306  * - the continuation is invoked via longjmp (or setcontext)
 307  *
 308  * This order is important so that unwind and rewind handlers are run
 309  * with their correct stack.
 310  */
 311
 312 static void scm_dynthrow (SCM);
 313
 314 /* Grow the stack by a fixed amount to provide space to copy in the
 315  * continuation.  Possibly this function has to be called several times
 316  * recursively before enough space is available.  Make sure the compiler does
 317  * not optimize the growth array away by storing it's address into a global
 318  * variable.
 319  */
 320
 321 static scm_t_bits scm_i_dummy;
 322
 323 static void
 324 grow_stack (SCM cont)
 325 {
 326   scm_t_bits growth[100];
 327
 328   scm_i_dummy = (scm_t_bits) growth;
 329   scm_dynthrow (cont);
 330 }
 331
 332
 333 /* Copy the continuation stack into the current stack.  Calling functions from
 334  * within this function is safe, since only stack frames below this function's
 335  * own frame are overwritten.  Thus, memcpy can be used for best performance.
 336  */
 337
 338 typedef struct {
 339   scm_t_contregs *continuation;
 340   SCM_STACKITEM *dst;
 341 } copy_stack_data;
 342
 343 static void
 344 copy_stack (void *data)
 345 {
 346   copy_stack_data *d = (copy_stack_data *)data;
 347   memcpy (d->dst, d->continuation->stack,
 348           sizeof (SCM_STACKITEM) * d->continuation->num_stack_items);
 349 #ifdef __ia64__
 350   SCM_I_CURRENT_THREAD->pending_rbs_continuation = d->continuation;
 351 #endif
 352 }
 353
 354 static void
 355 copy_stack_and_call (scm_t_contregs *continuation,
 356                      SCM_STACKITEM * dst)
 357 {
 358   long delta;
 359   copy_stack_data data;
 360
 361   delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv);
 362   data.continuation = continuation;
 363   data.dst = dst;
 364   scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data);
 365
 366   SCM_I_LONGJMP (continuation->jmpbuf, 1);
 367 }
 368
 369 #ifdef __ia64__
 370 void
 371 scm_ia64_longjmp (scm_i_jmp_buf *JB, int VAL)
 372 {
 373   scm_i_thread *t = SCM_I_CURRENT_THREAD;
 374
 375   if (t->pending_rbs_continuation)
 376     {
 377       memcpy (t->register_backing_store_base,
 378               t->pending_rbs_continuation->backing_store,
 379               t->pending_rbs_continuation->backing_store_size);
 380       t->pending_rbs_continuation = NULL;
 381     }
 382   setcontext (&JB->ctx);
 383 }
 384 #endif
 385
 386 /* Call grow_stack until the stack space is large enough, then, as the current
 387  * stack frame might get overwritten, let copy_stack_and_call perform the
 388  * actual copying and continuation calling.
 389  */
 390 static void
 391 scm_dynthrow (SCM cont)
 392 {
 393   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 394   scm_t_contregs *continuation = SCM_CONTREGS (cont);
 395   SCM_STACKITEM *dst = thread->continuation_base;
 396   SCM_STACKITEM stack_top_element;
 397
 398   if (thread->critical_section_level)
 399     {
 400       fprintf (stderr, "continuation invoked from within critical section.\n");
 401       abort ();
 402     }
 403
 404 #if SCM_STACK_GROWS_UP
 405   if (dst + continuation->num_stack_items >= &stack_top_element)
 406     grow_stack (cont);
 407 #else
 408   dst -= continuation->num_stack_items;
 409   if (dst <= &stack_top_element)
 410     grow_stack (cont);
 411 #endif /* def SCM_STACK_GROWS_UP */
 412
 413   SCM_FLUSH_REGISTER_WINDOWS;
 414   copy_stack_and_call (continuation, dst);
 415 }
 416
 417
 418 void
 419 scm_i_check_continuation (SCM cont)
 420 {
 421   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 422   scm_t_contregs *continuation = SCM_CONTREGS (cont);
 423
 424   if (!scm_is_eq (continuation->root, thread->continuation_root))
 425     scm_misc_error
 426       ("%continuation-call",
 427        "invoking continuation would cross continuation barrier: ~A",
 428        scm_list_1 (cont));
 429 }
 430
 431 void
 432 scm_i_reinstate_continuation (SCM cont)
 433 {
 434   scm_dynthrow (cont);
 435 }
 436
 437 SCM
 438 scm_i_with_continuation_barrier (scm_t_catch_body body,
 439                                  void *body_data,
 440                                  scm_t_catch_handler handler,
 441                                  void *handler_data,
 442                                  scm_t_catch_handler pre_unwind_handler,
 443                                  void *pre_unwind_handler_data)
 444 {
 445   SCM_STACKITEM stack_item;
 446   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 447   SCM old_controot;
 448   SCM_STACKITEM *old_contbase;
 449   SCM result;
 450
 451   /* Establish a fresh continuation root.
 452    */
 453   old_controot = thread->continuation_root;
 454   old_contbase = thread->continuation_base;
 455   thread->continuation_root = scm_cons (thread->handle, old_controot);
 456   thread->continuation_base = &stack_item;
 457
 458   /* Call FUNC inside a catch all.  This is now guaranteed to return
 459      directly and exactly once.
 460   */
 461   result = scm_c_catch (SCM_BOOL_T,
 462                         body, body_data,
 463                         handler, handler_data,
 464                         pre_unwind_handler, pre_unwind_handler_data);
 465
 466   /* Return to old continuation root.
 467    */
 468   thread->continuation_base = old_contbase;
 469   thread->continuation_root = old_controot;
 470
 471   return result;
 472 }
 473
 474 \f
 475
 476 static int
 477 should_print_backtrace (SCM tag, SCM stack)
 478 {
 479   return SCM_BACKTRACE_P
 480     && scm_is_true (stack)
 481     && scm_initialized_p
 482     /* It's generally not useful to print backtraces for errors reading
 483        or expanding code in these fallback catch statements. */
 484     && !scm_is_eq (tag, scm_from_latin1_symbol ("read-error"))
 485     && !scm_is_eq (tag, scm_from_latin1_symbol ("syntax-error"));
 486 }
 487
 488 static void
 489 print_exception_and_backtrace (SCM port, SCM tag, SCM args)
 490 {
 491   SCM stack, frame;
 492
 493   /* We get here via a throw to a catch-all.  In that case there is the
 494      throw frame active, and this catch closure, so narrow by two
 495      frames.  */
 496   stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2)));
 497   frame = scm_is_true (stack) ? scm_stack_ref (stack, SCM_INUM0) : SCM_BOOL_F;
 498
 499   if (should_print_backtrace (tag, stack))
 500     {
 501       scm_puts_unlocked ("Backtrace:\n", port);
 502       scm_display_backtrace_with_highlights (stack, port,
 503                                              SCM_BOOL_F, SCM_BOOL_F,
 504                                              SCM_EOL);
 505       scm_newline (port);
 506     }
 507
 508   scm_print_exception (port, frame, tag, args);
 509 }
 510
 511 \f
 512
 513 struct c_data {
 514   void *(*func) (void *);
 515   void *data;
 516   void *result;
 517 };
 518
 519 static SCM
 520 c_body (void *d)
 521 {
 522   struct c_data *data = (struct c_data *)d;
 523   data->result = data->func (data->data);
 524   return SCM_UNSPECIFIED;
 525 }
 526
 527 static SCM
 528 c_handler (void *d, SCM tag, SCM args)
 529 {
 530   struct c_data *data;
 531
 532   /* If TAG is `quit', exit() the process.  */
 533   if (scm_is_eq (tag, scm_from_latin1_symbol ("quit")))
 534     exit (scm_exit_status (args));
 535
 536   data = (struct c_data *)d;
 537   data->result = NULL;
 538   return SCM_UNSPECIFIED;
 539 }
 540
 541 static SCM
 542 pre_unwind_handler (void *error_port, SCM tag, SCM args)
 543 {
 544   /* Print the exception unless TAG is  `quit'.  */
 545   if (!scm_is_eq (tag, scm_from_latin1_symbol ("quit")))
 546     print_exception_and_backtrace (SCM_PACK_POINTER (error_port), tag, args);
 547
 548   return SCM_UNSPECIFIED;
 549 }
 550
 551 void *
 552 scm_c_with_continuation_barrier (void *(*func) (void *), void *data)
 553 {
 554   struct c_data c_data;
 555   c_data.func = func;
 556   c_data.data = data;
 557   scm_i_with_continuation_barrier (c_body, &c_data,
 558                                    c_handler, &c_data,
 559                                    pre_unwind_handler,
 560                                    SCM_UNPACK_POINTER (scm_current_error_port ()));
 561   return c_data.result;
 562 }
 563
 564 struct scm_data {
 565   SCM proc;
 566 };
 567
 568 static SCM
 569 scm_body (void *d)
 570 {
 571   struct scm_data *data = (struct scm_data *)d;
 572   return scm_call_0 (data->proc);
 573 }
 574
 575 static SCM
 576 scm_handler (void *d, SCM tag, SCM args)
 577 {
 578   /* Print a message.  Note that if TAG is `quit', this will exit() the
 579      process.  */
 580   scm_handle_by_message_noexit (NULL, tag, args);
 581
 582   return SCM_BOOL_F;
 583 }
 584
 585 SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0,
 586             (SCM proc),
 587 "Call @var{proc} and return its result.  Do not allow the invocation of\n"
 588 "continuations that would leave or enter the dynamic extent of the call\n"
 589 "to @code{with-continuation-barrier}.  Such an attempt causes an error\n"
 590 "to be signaled.\n"
 591 "\n"
 592 "Throws (such as errors) that are not caught from within @var{proc} are\n"
 593 "caught by @code{with-continuation-barrier}.  In that case, a short\n"
 594 "message is printed to the current error port and @code{#f} is returned.\n"
 595 "\n"
 596 "Thus, @code{with-continuation-barrier} returns exactly once.\n")
 597 #define FUNC_NAME s_scm_with_continuation_barrier
 598 {
 599   struct scm_data scm_data;
 600   scm_data.proc = proc;
 601   return scm_i_with_continuation_barrier (scm_body, &scm_data,
 602                                           scm_handler, &scm_data,
 603                                           pre_unwind_handler,
 604                                           SCM_UNPACK_POINTER (scm_current_error_port ()));
 605 }
 606 #undef FUNC_NAME
 607
 608 void
 609 scm_init_continuations ()
 610 {
 611   tc16_continuation = scm_make_smob_type ("continuation", 0);
 612   scm_set_smob_print (tc16_continuation, continuation_print);
 613 #include "libguile/continuations.x"
 614 }
 615
 616 /*
 617   Local Variables:
 618   c-file-style: "gnu"
 619   End:
 620 */