libguile/continuations.c

   1 /* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006, 2008, 2009, 2010, 2011, 2012 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 <assert.h>
  28 #include <string.h>
  29 #include <stdio.h>
  30
  31 #include "libguile/async.h"
  32 #include "libguile/debug.h"
  33 #include "libguile/root.h"
  34 #include "libguile/stackchk.h"
  35 #include "libguile/smob.h"
  36 #include "libguile/ports.h"
  37 #include "libguile/dynstack.h"
  38 #include "libguile/eval.h"
  39 #include "libguile/vm.h"
  40 #include "libguile/instructions.h"
  41
  42 #include "libguile/validate.h"
  43 #include "libguile/continuations.h"
  44
  45 \f
  46
  47 static scm_t_bits tc16_continuation;
  48 #define SCM_CONTREGSP(x)        SCM_TYP16_PREDICATE (tc16_continuation, x)
  49
  50 #define SCM_CONTREGS(x)         ((scm_t_contregs *) SCM_SMOB_DATA_1 (x))
  51
  52 #define SCM_CONTINUATION_LENGTH(x) (SCM_CONTREGS (x)->num_stack_items)
  53 #define SCM_SET_CONTINUATION_LENGTH(x, n)\
  54    (SCM_CONTREGS (x)->num_stack_items = (n))
  55 #define SCM_JMPBUF(x)            ((SCM_CONTREGS (x))->jmpbuf)
  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 OBJCODE_TAG SCM_MAKE_OBJCODE_TAG (SCM_OBJCODE_TYPE_STATIC, 0)
  75
  76 #if defined (SCM_ALIGNED) && 0
  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 #define SCM_STATIC_OBJCODE(sym)                                         \
  82   SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode);      \
  83   SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = {            \
  84     { SCM_PACK (OBJCODE_TAG), SCM_PACK (sym##__bytecode) },             \
  85     { SCM_BOOL_F, SCM_PACK (0) }                                        \
  86   };                                                                    \
  87   static const SCM sym = SCM_PACK (sym##__cells);                       \
  88   SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode)
  89 #else
  90 #define SCM_STATIC_OBJCODE(sym)                                         \
  91 static SCM sym;                                                         \
  92 static scm_t_uint8 *sym##_bytecode;                                     \
  93 SCM_SNARF_INIT(sym##_bytecode = scm_gc_malloc_pointerless (sizeof(sym##_bytecode__unaligned), "partial continuation stub"); \
  94                memcpy (sym##_bytecode, sym##_bytecode__unaligned, sizeof(sym##_bytecode__unaligned));) \
  95 SCM_SNARF_INIT(sym = scm_double_cell (OBJCODE_TAG,                      \
  96                                       (scm_t_bits)sym##_bytecode,       \
  97                                       SCM_UNPACK (SCM_BOOL_F),          \
  98                                       0);)                              \
  99 static const scm_t_uint8 sym##_bytecode__unaligned[]
 100 #endif
 101
 102
 103 SCM_STATIC_OBJCODE (cont_objcode) = {
 104   /* This code is the same as in gsubr.c, except we use continuation_call
 105      instead of subr_call. */
 106   OBJCODE_HEADER (8, 19),
 107   /* leave args on the stack */
 108   /* 0 */ scm_op_object_ref, 0, /* push scm_t_contregs smob */
 109   /* 2 */ scm_op_continuation_call, /* and longjmp (whee) */
 110   /* 3 */ scm_op_nop, /* pad to 8 bytes */
 111   /* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop,
 112   /* 8 */
 113
 114   /* We could put some meta-info to say that this proc is a continuation. Not sure
 115      how to do that, though. */
 116   META_HEADER (19),
 117   /* 0 */ scm_op_make_eol, /* bindings */
 118   /* 1 */ scm_op_make_eol, /* sources */
 119   /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */
 120   /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */
 121   /* 7 */ scm_op_make_int8_0, /* 0 optionals */
 122   /* 8 */ scm_op_make_true, /* and a rest arg */
 123   /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */
 124   /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */
 125   /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */
 126   /* 18 */ scm_op_return /* and return */
 127   /* 19 */
 128 };
 129
 130
 131 SCM_STATIC_OBJCODE (call_cc_objcode) = {
 132   /* Before Scheme's call/cc is compiled, eval.c will use this hand-coded
 133      call/cc. */
 134   OBJCODE_HEADER (8, 17),
 135   /* 0 */ scm_op_assert_nargs_ee, 0, 1, /* assert that nargs==1 */
 136   /* 3 */ scm_op_local_ref, 0, /* push the proc */
 137   /* 5 */ scm_op_tail_call_cc, /* and call/cc */
 138   /* 6 */ scm_op_nop, scm_op_nop, /* pad to 8 bytes */
 139   /* 8 */
 140
 141   META_HEADER (17),
 142   /* 0 */ scm_op_make_eol, /* bindings */
 143   /* 1 */ scm_op_make_eol, /* sources */
 144   /* 2 */ scm_op_make_int8, 3, scm_op_make_int8, 6, /* arity: from ip 0 to ip 6 */
 145   /* 6 */ scm_op_make_int8_1, /* the arity is 0 required args */
 146   /* 7 */ scm_op_list, 0, 3, /* make a list of those 5 vals */
 147   /* 10 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */
 148   /* 13 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */
 149   /* 16 */ scm_op_return /* and return */
 150   /* 17 */
 151 };
 152
 153
 154 static SCM
 155 make_continuation_trampoline (SCM contregs)
 156 {
 157   SCM ret = scm_make_program (cont_objcode,
 158                               scm_c_make_vector (1, contregs),
 159                               SCM_BOOL_F);
 160   SCM_SET_CELL_WORD_0 (ret,
 161                        SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_CONTINUATION);
 162
 163   return ret;
 164 }
 165
 166
 167 /* {Continuations}
 168  */
 169
 170
 171 static int
 172 continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED)
 173 {
 174   scm_t_contregs *continuation = SCM_CONTREGS (obj);
 175
 176   scm_puts_unlocked ("#<continuation ", port);
 177   scm_intprint (continuation->num_stack_items, 10, port);
 178   scm_puts_unlocked (" @ ", port);
 179   scm_uintprint (SCM_SMOB_DATA_1 (obj), 16, port);
 180   scm_putc_unlocked ('>', port);
 181   return 1;
 182 }
 183
 184 /* James Clark came up with this neat one instruction fix for
 185  * continuations on the SPARC.  It flushes the register windows so
 186  * that all the state of the process is contained in the stack.
 187  */
 188
 189 #if defined (sparc) || defined (__sparc__) || defined (__sparc)
 190 # define SCM_FLUSH_REGISTER_WINDOWS asm("ta 3")
 191 #else
 192 # define SCM_FLUSH_REGISTER_WINDOWS /* empty */
 193 #endif
 194
 195 /* this may return more than once: the first time with the escape
 196    procedure, then subsequently with SCM_UNDEFINED (the vals already having been
 197    placed on the VM stack). */
 198 #define FUNC_NAME "scm_i_make_continuation"
 199 SCM
 200 scm_i_make_continuation (int *first, SCM vm, SCM vm_cont)
 201 {
 202   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 203   SCM cont;
 204   scm_t_contregs *continuation;
 205   long stack_size;
 206   SCM_STACKITEM * src;
 207
 208   SCM_FLUSH_REGISTER_WINDOWS;
 209   stack_size = scm_stack_size (thread->continuation_base);
 210   continuation = scm_gc_malloc (sizeof (scm_t_contregs)
 211                                 + (stack_size - 1) * sizeof (SCM_STACKITEM),
 212                                 "continuation");
 213   continuation->num_stack_items = stack_size;
 214   continuation->root = thread->continuation_root;
 215   src = thread->continuation_base;
 216 #if ! SCM_STACK_GROWS_UP
 217   src -= stack_size;
 218 #endif
 219   continuation->offset = continuation->stack - src;
 220   memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size);
 221   continuation->vm = vm;
 222   continuation->vm_cont = vm_cont;
 223
 224   SCM_NEWSMOB (cont, tc16_continuation, continuation);
 225
 226   *first = !SCM_I_SETJMP (continuation->jmpbuf);
 227   if (*first)
 228     {
 229 #ifdef __ia64__
 230       continuation->backing_store_size =
 231         (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx)
 232         -
 233         (char *) thread->register_backing_store_base;
 234       continuation->backing_store = NULL;
 235       continuation->backing_store =
 236         scm_gc_malloc (continuation->backing_store_size,
 237                        "continuation backing store");
 238       memcpy (continuation->backing_store,
 239               (void *) thread->register_backing_store_base,
 240               continuation->backing_store_size);
 241 #endif /* __ia64__ */
 242       return make_continuation_trampoline (cont);
 243     }
 244   else
 245     return SCM_UNDEFINED;
 246 }
 247 #undef FUNC_NAME
 248
 249 SCM
 250 scm_i_call_with_current_continuation (SCM proc)
 251 {
 252   static SCM call_cc = SCM_BOOL_F;
 253
 254   if (scm_is_false (call_cc))
 255     call_cc = scm_make_program (call_cc_objcode, SCM_BOOL_F, SCM_BOOL_F);
 256
 257   return scm_call_1 (call_cc, proc);
 258 }
 259
 260 SCM
 261 scm_i_continuation_to_frame (SCM continuation)
 262 {
 263   SCM contregs;
 264   scm_t_contregs *cont;
 265
 266   contregs = scm_c_vector_ref (scm_program_objects (continuation), 0);
 267   cont = SCM_CONTREGS (contregs);
 268
 269   if (scm_is_true (cont->vm_cont))
 270     {
 271       struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont);
 272       return scm_c_make_frame (cont->vm_cont,
 273                                data->fp + data->reloc,
 274                                data->sp + data->reloc,
 275                                data->ra,
 276                                data->reloc);
 277     }
 278   else
 279     return SCM_BOOL_F;
 280 }
 281
 282 SCM
 283 scm_i_contregs_vm (SCM contregs)
 284 {
 285   return SCM_CONTREGS (contregs)->vm;
 286 }
 287
 288 SCM
 289 scm_i_contregs_vm_cont (SCM contregs)
 290 {
 291   return SCM_CONTREGS (contregs)->vm_cont;
 292 }
 293
 294
 295 /* {Apply}
 296  */
 297
 298 /* Invoking a continuation proceeds as follows:
 299  *
 300  * - the stack is made large enough for the called continuation
 301  * - the old windchain is unwound down to the branching point
 302  * - the continuation stack is copied into place
 303  * - the windchain is rewound up to the continuation's context
 304  * - the continuation is invoked via longjmp (or setcontext)
 305  *
 306  * This order is important so that unwind and rewind handlers are run
 307  * with their correct stack.
 308  */
 309
 310 static void scm_dynthrow (SCM);
 311
 312 /* Grow the stack by a fixed amount to provide space to copy in the
 313  * continuation.  Possibly this function has to be called several times
 314  * recursively before enough space is available.  Make sure the compiler does
 315  * not optimize the growth array away by storing it's address into a global
 316  * variable.
 317  */
 318
 319 static scm_t_bits scm_i_dummy;
 320
 321 static void
 322 grow_stack (SCM cont)
 323 {
 324   scm_t_bits growth[100];
 325
 326   scm_i_dummy = (scm_t_bits) growth;
 327   scm_dynthrow (cont);
 328 }
 329
 330
 331 /* Copy the continuation stack into the current stack.  Calling functions from
 332  * within this function is safe, since only stack frames below this function's
 333  * own frame are overwritten.  Thus, memcpy can be used for best performance.
 334  */
 335
 336 static void
 337 copy_stack_and_call (scm_t_contregs *continuation,
 338                      SCM_STACKITEM * dst)
 339 {
 340   scm_t_dynstack *dynstack;
 341   scm_t_bits *joint;
 342   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 343
 344   dynstack = SCM_VM_CONT_DATA (continuation->vm_cont)->dynstack;
 345
 346   joint = scm_dynstack_unwind_fork (&thread->dynstack, dynstack);
 347
 348   memcpy (dst, continuation->stack,
 349           sizeof (SCM_STACKITEM) * continuation->num_stack_items);
 350 #ifdef __ia64__
 351   thread->pending_rbs_continuation = continuation;
 352 #endif
 353
 354   scm_dynstack_wind (&thread->dynstack, joint);
 355
 356   SCM_I_LONGJMP (continuation->jmpbuf, 1);
 357 }
 358
 359 #ifdef __ia64__
 360 void
 361 scm_ia64_longjmp (scm_i_jmp_buf *JB, int VAL)
 362 {
 363   scm_i_thread *t = SCM_I_CURRENT_THREAD;
 364
 365   if (t->pending_rbs_continuation)
 366     {
 367       memcpy (t->register_backing_store_base,
 368               t->pending_rbs_continuation->backing_store,
 369               t->pending_rbs_continuation->backing_store_size);
 370       t->pending_rbs_continuation = NULL;
 371     }
 372   setcontext (&JB->ctx);
 373 }
 374 #endif
 375
 376 /* Call grow_stack until the stack space is large enough, then, as the current
 377  * stack frame might get overwritten, let copy_stack_and_call perform the
 378  * actual copying and continuation calling.
 379  */
 380 static void
 381 scm_dynthrow (SCM cont)
 382 {
 383   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 384   scm_t_contregs *continuation = SCM_CONTREGS (cont);
 385   SCM_STACKITEM *dst = thread->continuation_base;
 386   SCM_STACKITEM stack_top_element;
 387
 388   if (thread->critical_section_level)
 389     {
 390       fprintf (stderr, "continuation invoked from within critical section.\n");
 391       abort ();
 392     }
 393
 394 #if SCM_STACK_GROWS_UP
 395   if (dst + continuation->num_stack_items >= &stack_top_element)
 396     grow_stack (cont);
 397 #else
 398   dst -= continuation->num_stack_items;
 399   if (dst <= &stack_top_element)
 400     grow_stack (cont);
 401 #endif /* def SCM_STACK_GROWS_UP */
 402
 403   SCM_FLUSH_REGISTER_WINDOWS;
 404   copy_stack_and_call (continuation, dst);
 405 }
 406
 407
 408 void
 409 scm_i_check_continuation (SCM cont)
 410 {
 411   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 412   scm_t_contregs *continuation = SCM_CONTREGS (cont);
 413
 414   if (!scm_is_eq (continuation->root, thread->continuation_root))
 415     scm_misc_error
 416       ("%continuation-call",
 417        "invoking continuation would cross continuation barrier: ~A",
 418        scm_list_1 (cont));
 419 }
 420
 421 void
 422 scm_i_reinstate_continuation (SCM cont)
 423 {
 424   scm_dynthrow (cont);
 425 }
 426
 427 SCM
 428 scm_i_with_continuation_barrier (scm_t_catch_body body,
 429                                  void *body_data,
 430                                  scm_t_catch_handler handler,
 431                                  void *handler_data,
 432                                  scm_t_catch_handler pre_unwind_handler,
 433                                  void *pre_unwind_handler_data)
 434 {
 435   SCM_STACKITEM stack_item;
 436   scm_i_thread *thread = SCM_I_CURRENT_THREAD;
 437   SCM old_controot;
 438   SCM_STACKITEM *old_contbase;
 439   SCM result;
 440
 441   /* Establish a fresh continuation root.
 442    */
 443   old_controot = thread->continuation_root;
 444   old_contbase = thread->continuation_base;
 445   thread->continuation_root = scm_cons (thread->handle, old_controot);
 446   thread->continuation_base = &stack_item;
 447
 448   /* Call FUNC inside a catch all.  This is now guaranteed to return
 449      directly and exactly once.
 450   */
 451   result = scm_c_catch (SCM_BOOL_T,
 452                         body, body_data,
 453                         handler, handler_data,
 454                         pre_unwind_handler, pre_unwind_handler_data);
 455
 456   /* Return to old continuation root.
 457    */
 458   thread->continuation_base = old_contbase;
 459   thread->continuation_root = old_controot;
 460
 461   return result;
 462 }
 463
 464 \f
 465
 466 static int
 467 should_print_backtrace (SCM tag, SCM stack)
 468 {
 469   return SCM_BACKTRACE_P
 470     && scm_is_true (stack)
 471     && scm_initialized_p
 472     /* It's generally not useful to print backtraces for errors reading
 473        or expanding code in these fallback catch statements. */
 474     && !scm_is_eq (tag, scm_from_latin1_symbol ("read-error"))
 475     && !scm_is_eq (tag, scm_from_latin1_symbol ("syntax-error"));
 476 }
 477
 478 static void
 479 print_exception_and_backtrace (SCM port, SCM tag, SCM args)
 480 {
 481   SCM stack, frame;
 482
 483   /* We get here via a throw to a catch-all.  In that case there is the
 484      throw frame active, and this catch closure, so narrow by two
 485      frames.  */
 486   stack = scm_make_stack (SCM_BOOL_T, scm_list_1 (scm_from_int (2)));
 487   frame = scm_is_true (stack) ? scm_stack_ref (stack, SCM_INUM0) : SCM_BOOL_F;
 488
 489   if (should_print_backtrace (tag, stack))
 490     {
 491       scm_puts_unlocked ("Backtrace:\n", port);
 492       scm_display_backtrace_with_highlights (stack, port,
 493                                              SCM_BOOL_F, SCM_BOOL_F,
 494                                              SCM_EOL);
 495       scm_newline (port);
 496     }
 497
 498   scm_print_exception (port, frame, tag, args);
 499 }
 500
 501 \f
 502
 503 struct c_data {
 504   void *(*func) (void *);
 505   void *data;
 506   void *result;
 507 };
 508
 509 static SCM
 510 c_body (void *d)
 511 {
 512   struct c_data *data = (struct c_data *)d;
 513   data->result = data->func (data->data);
 514   return SCM_UNSPECIFIED;
 515 }
 516
 517 static SCM
 518 c_handler (void *d, SCM tag, SCM args)
 519 {
 520   struct c_data *data;
 521
 522   /* If TAG is `quit', exit() the process.  */
 523   if (scm_is_eq (tag, scm_from_latin1_symbol ("quit")))
 524     exit (scm_exit_status (args));
 525
 526   data = (struct c_data *)d;
 527   data->result = NULL;
 528   return SCM_UNSPECIFIED;
 529 }
 530
 531 static SCM
 532 pre_unwind_handler (void *error_port, SCM tag, SCM args)
 533 {
 534   /* Print the exception unless TAG is  `quit'.  */
 535   if (!scm_is_eq (tag, scm_from_latin1_symbol ("quit")))
 536     print_exception_and_backtrace (SCM_PACK_POINTER (error_port), tag, args);
 537
 538   return SCM_UNSPECIFIED;
 539 }
 540
 541 void *
 542 scm_c_with_continuation_barrier (void *(*func) (void *), void *data)
 543 {
 544   struct c_data c_data;
 545   c_data.func = func;
 546   c_data.data = data;
 547   scm_i_with_continuation_barrier (c_body, &c_data,
 548                                    c_handler, &c_data,
 549                                    pre_unwind_handler,
 550                                    SCM_UNPACK_POINTER (scm_current_error_port ()));
 551   return c_data.result;
 552 }
 553
 554 struct scm_data {
 555   SCM proc;
 556 };
 557
 558 static SCM
 559 scm_body (void *d)
 560 {
 561   struct scm_data *data = (struct scm_data *)d;
 562   return scm_call_0 (data->proc);
 563 }
 564
 565 static SCM
 566 scm_handler (void *d, SCM tag, SCM args)
 567 {
 568   /* Print a message.  Note that if TAG is `quit', this will exit() the
 569      process.  */
 570   scm_handle_by_message_noexit (NULL, tag, args);
 571
 572   return SCM_BOOL_F;
 573 }
 574
 575 SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0,
 576             (SCM proc),
 577 "Call @var{proc} and return its result.  Do not allow the invocation of\n"
 578 "continuations that would leave or enter the dynamic extent of the call\n"
 579 "to @code{with-continuation-barrier}.  Such an attempt causes an error\n"
 580 "to be signaled.\n"
 581 "\n"
 582 "Throws (such as errors) that are not caught from within @var{proc} are\n"
 583 "caught by @code{with-continuation-barrier}.  In that case, a short\n"
 584 "message is printed to the current error port and @code{#f} is returned.\n"
 585 "\n"
 586 "Thus, @code{with-continuation-barrier} returns exactly once.\n")
 587 #define FUNC_NAME s_scm_with_continuation_barrier
 588 {
 589   struct scm_data scm_data;
 590   scm_data.proc = proc;
 591   return scm_i_with_continuation_barrier (scm_body, &scm_data,
 592                                           scm_handler, &scm_data,
 593                                           pre_unwind_handler,
 594                                           SCM_UNPACK_POINTER (scm_current_error_port ()));
 595 }
 596 #undef FUNC_NAME
 597
 598 void
 599 scm_init_continuations ()
 600 {
 601   tc16_continuation = scm_make_smob_type ("continuation", 0);
 602   scm_set_smob_print (tc16_continuation, continuation_print);
 603 #include "libguile/continuations.x"
 604 }
 605
 606 /*
 607   Local Variables:
 608   c-file-style: "gnu"
 609   End:
 610 */