Commit | Line | Data |
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5afcf08b | 1 | /* Copyright (C) 1995,1996,1998,2000,2001,2004 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e MV |
3 | * This library is free software; you can redistribute it and/or |
4 | * modify it under the terms of the GNU Lesser General Public | |
5 | * License as published by the Free Software Foundation; either | |
6 | * version 2.1 of the License, or (at your option) any later version. | |
0f2d19dd | 7 | * |
73be1d9e MV |
8 | * This library is distributed in the hope that it will be useful, |
9 | * but 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. | |
0f2d19dd | 12 | * |
73be1d9e MV |
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
16 | */ | |
1bbd0b84 | 17 | |
1bbd0b84 | 18 | |
0f2d19dd JB |
19 | \f |
20 | ||
bbd43f03 RB |
21 | #include "libguile/_scm.h" |
22 | ||
13070bd3 DH |
23 | #include <string.h> |
24 | ||
d0f6ceb8 | 25 | #include "libguile/debug.h" |
a0599745 MD |
26 | #include "libguile/root.h" |
27 | #include "libguile/stackchk.h" | |
5f144b10 GH |
28 | #include "libguile/smob.h" |
29 | #include "libguile/ports.h" | |
30 | #include "libguile/dynwind.h" | |
ce212434 | 31 | #include "libguile/values.h" |
9de87eea | 32 | #include "libguile/eval.h" |
5f144b10 | 33 | |
db4b4ca6 | 34 | #include "libguile/validate.h" |
a0599745 | 35 | #include "libguile/continuations.h" |
01c8a3dd | 36 | |
0f2d19dd JB |
37 | \f |
38 | ||
39 | /* {Continuations} | |
40 | */ | |
41 | ||
92c2555f | 42 | scm_t_bits scm_tc16_continuation; |
0f2d19dd | 43 | |
e841c3e0 KN |
44 | static SCM |
45 | continuation_mark (SCM obj) | |
5f144b10 | 46 | { |
92c2555f | 47 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
01c8a3dd | 48 | |
9de87eea | 49 | scm_gc_mark (continuation->root); |
5f144b10 GH |
50 | scm_gc_mark (continuation->throw_value); |
51 | scm_mark_locations (continuation->stack, continuation->num_stack_items); | |
193297d8 RB |
52 | #ifdef __ia64__ |
53 | if (continuation->backing_store) | |
54 | scm_mark_locations (continuation->backing_store, | |
55 | continuation->backing_store_size / | |
56 | sizeof (SCM_STACKITEM)); | |
57 | #endif /* __ia64__ */ | |
5f144b10 GH |
58 | return continuation->dynenv; |
59 | } | |
01c8a3dd | 60 | |
1be6b49c | 61 | static size_t |
e841c3e0 | 62 | continuation_free (SCM obj) |
5f144b10 | 63 | { |
92c2555f | 64 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
9de87eea | 65 | /* stack array size is 1 if num_stack_items is 0. */ |
1be6b49c | 66 | size_t extra_items = (continuation->num_stack_items > 0) |
5f144b10 GH |
67 | ? (continuation->num_stack_items - 1) |
68 | : 0; | |
92c2555f | 69 | size_t bytes_free = sizeof (scm_t_contregs) |
5f144b10 | 70 | + extra_items * sizeof (SCM_STACKITEM); |
193297d8 RB |
71 | |
72 | #ifdef __ia64__ | |
4c9419ac MV |
73 | scm_gc_free (continuation->backing_store, continuation->backing_store_size, |
74 | "continuation backing store"); | |
193297d8 | 75 | #endif /* __ia64__ */ |
4c9419ac MV |
76 | scm_gc_free (continuation, bytes_free, "continuation"); |
77 | return 0; | |
5f144b10 | 78 | } |
01c8a3dd | 79 | |
e841c3e0 | 80 | static int |
e81d98ec | 81 | continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED) |
5f144b10 | 82 | { |
92c2555f | 83 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
5f144b10 GH |
84 | |
85 | scm_puts ("#<continuation ", port); | |
86 | scm_intprint (continuation->num_stack_items, 10, port); | |
87 | scm_puts (" @ ", port); | |
0345e278 | 88 | scm_uintprint (SCM_CELL_WORD_1 (obj), 16, port); |
5f144b10 GH |
89 | scm_putc ('>', port); |
90 | return 1; | |
91 | } | |
1cc91f1b | 92 | |
193297d8 | 93 | #ifdef __ia64__ |
87855fa2 MV |
94 | /* Extern declaration of getcontext()/setcontext() in order to redefine |
95 | getcontext() since on ia64-linux the second return value indicates whether | |
96 | it returned from getcontext() itself or by running setcontext(). */ | |
193297d8 RB |
97 | struct rv |
98 | { | |
99 | long retval; | |
100 | long first_return; | |
101 | }; | |
78b6566e | 102 | extern struct rv ia64_getcontext (ucontext_t *) __asm__ ("getcontext"); |
193297d8 RB |
103 | #endif /* __ia64__ */ |
104 | ||
5f144b10 GH |
105 | /* this may return more than once: the first time with the escape |
106 | procedure, then subsequently with the value to be passed to the | |
107 | continuation. */ | |
108 | #define FUNC_NAME "scm_make_continuation" | |
0f2d19dd | 109 | SCM |
5f144b10 | 110 | scm_make_continuation (int *first) |
0f2d19dd | 111 | { |
9de87eea MV |
112 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
113 | SCM cont; | |
92c2555f | 114 | scm_t_contregs *continuation; |
c014a02e | 115 | long stack_size; |
01c8a3dd | 116 | SCM_STACKITEM * src; |
193297d8 RB |
117 | #ifdef __ia64__ |
118 | struct rv rv; | |
87855fa2 | 119 | #endif /* __ia64__ */ |
0f2d19dd | 120 | |
0f2d19dd | 121 | SCM_FLUSH_REGISTER_WINDOWS; |
9de87eea | 122 | stack_size = scm_stack_size (thread->continuation_base); |
4c9419ac MV |
123 | continuation = scm_gc_malloc (sizeof (scm_t_contregs) |
124 | + (stack_size - 1) * sizeof (SCM_STACKITEM), | |
125 | "continuation"); | |
5f144b10 | 126 | continuation->num_stack_items = stack_size; |
9de87eea | 127 | continuation->dynenv = scm_i_dynwinds (); |
5f144b10 | 128 | continuation->throw_value = SCM_EOL; |
9de87eea MV |
129 | continuation->root = thread->continuation_root; |
130 | continuation->dframe = scm_i_last_debug_frame (); | |
131 | src = thread->continuation_base; | |
5f144b10 | 132 | SCM_NEWSMOB (cont, scm_tc16_continuation, continuation); |
01c8a3dd | 133 | |
4ccb2cd2 | 134 | #if ! SCM_STACK_GROWS_UP |
5f144b10 GH |
135 | src -= stack_size; |
136 | #endif | |
5c5c27dc | 137 | continuation->offset = continuation->stack - src; |
5f144b10 GH |
138 | memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size); |
139 | ||
193297d8 | 140 | #ifdef __ia64__ |
78b6566e | 141 | rv = ia64_getcontext (&continuation->ctx); |
193297d8 RB |
142 | if (rv.first_return) |
143 | { | |
144 | continuation->backing_store_size = | |
145 | continuation->ctx.uc_mcontext.sc_ar_bsp - | |
87855fa2 | 146 | (unsigned long) __libc_ia64_register_backing_store_base; |
193297d8 RB |
147 | continuation->backing_store = NULL; |
148 | continuation->backing_store = | |
4c9419ac MV |
149 | scm_gc_malloc (continuation->backing_store_size, |
150 | "continuation backing store"); | |
193297d8 RB |
151 | memcpy (continuation->backing_store, |
152 | (void *) __libc_ia64_register_backing_store_base, | |
153 | continuation->backing_store_size); | |
154 | *first = 1; | |
155 | return cont; | |
156 | } | |
157 | else | |
158 | { | |
3c468478 | 159 | SCM ret = continuation->throw_value; |
193297d8 | 160 | *first = 0; |
3c468478 MV |
161 | continuation->throw_value = SCM_BOOL_F; |
162 | return ret; | |
193297d8 RB |
163 | } |
164 | #else /* !__ia64__ */ | |
5f144b10 GH |
165 | if (setjmp (continuation->jmpbuf)) |
166 | { | |
3c468478 | 167 | SCM ret = continuation->throw_value; |
5f144b10 | 168 | *first = 0; |
3c468478 MV |
169 | continuation->throw_value = SCM_BOOL_F; |
170 | return ret; | |
5f144b10 GH |
171 | } |
172 | else | |
173 | { | |
174 | *first = 1; | |
175 | return cont; | |
176 | } | |
193297d8 | 177 | #endif /* !__ia64__ */ |
0f2d19dd | 178 | } |
5f144b10 | 179 | #undef FUNC_NAME |
0f2d19dd | 180 | |
d3c6aef9 MV |
181 | |
182 | /* Invoking a continuation proceeds as follows: | |
183 | * | |
184 | * - the stack is made large enough for the called continuation | |
185 | * - the old windchain is unwound down to the branching point | |
186 | * - the continuation stack is copied into place | |
187 | * - the windchain is rewound up to the continuation's context | |
188 | * - the continuation is invoked via longjmp (or setcontext) | |
189 | * | |
190 | * This order is important so that unwind and rewind handlers are run | |
191 | * with their correct stack. | |
192 | */ | |
193 | ||
5f144b10 | 194 | static void scm_dynthrow (SCM, SCM); |
01c8a3dd DH |
195 | |
196 | /* Grow the stack by a fixed amount to provide space to copy in the | |
197 | * continuation. Possibly this function has to be called several times | |
198 | * recursively before enough space is available. Make sure the compiler does | |
199 | * not optimize the growth array away by storing it's address into a global | |
200 | * variable. | |
201 | */ | |
202 | ||
92c2555f | 203 | scm_t_bits scm_i_dummy; |
1cc91f1b | 204 | |
0f2d19dd | 205 | static void |
01c8a3dd DH |
206 | grow_stack (SCM cont, SCM val) |
207 | { | |
92c2555f | 208 | scm_t_bits growth[100]; |
01c8a3dd | 209 | |
92c2555f | 210 | scm_i_dummy = (scm_t_bits) growth; |
01c8a3dd | 211 | scm_dynthrow (cont, val); |
0f2d19dd | 212 | } |
0f2d19dd | 213 | |
1cc91f1b | 214 | |
01c8a3dd DH |
215 | /* Copy the continuation stack into the current stack. Calling functions from |
216 | * within this function is safe, since only stack frames below this function's | |
217 | * own frame are overwritten. Thus, memcpy can be used for best performance. | |
218 | */ | |
d3c6aef9 MV |
219 | |
220 | typedef struct { | |
221 | scm_t_contregs *continuation; | |
222 | SCM_STACKITEM *dst; | |
223 | } copy_stack_data; | |
224 | ||
01c8a3dd | 225 | static void |
d3c6aef9 MV |
226 | copy_stack (void *data) |
227 | { | |
228 | copy_stack_data *d = (copy_stack_data *)data; | |
229 | memcpy (d->dst, d->continuation->stack, | |
230 | sizeof (SCM_STACKITEM) * d->continuation->num_stack_items); | |
231 | } | |
232 | ||
233 | static void | |
234 | copy_stack_and_call (scm_t_contregs *continuation, SCM val, | |
5f144b10 | 235 | SCM_STACKITEM * dst) |
0f2d19dd | 236 | { |
d3c6aef9 MV |
237 | long delta; |
238 | copy_stack_data data; | |
239 | ||
9de87eea | 240 | delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv); |
d3c6aef9 MV |
241 | data.continuation = continuation; |
242 | data.dst = dst; | |
14578fa4 | 243 | scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data); |
01c8a3dd | 244 | |
9de87eea | 245 | scm_i_set_last_debug_frame (continuation->dframe); |
01c8a3dd | 246 | |
5f144b10 | 247 | continuation->throw_value = val; |
193297d8 RB |
248 | #ifdef __ia64__ |
249 | memcpy ((void *) __libc_ia64_register_backing_store_base, | |
250 | continuation->backing_store, | |
251 | continuation->backing_store_size); | |
252 | setcontext (&continuation->ctx); | |
253 | #else | |
5f144b10 | 254 | longjmp (continuation->jmpbuf, 1); |
193297d8 | 255 | #endif |
01c8a3dd DH |
256 | } |
257 | ||
01c8a3dd DH |
258 | /* Call grow_stack until the stack space is large enough, then, as the current |
259 | * stack frame might get overwritten, let copy_stack_and_call perform the | |
260 | * actual copying and continuation calling. | |
261 | */ | |
262 | static void | |
263 | scm_dynthrow (SCM cont, SCM val) | |
264 | { | |
9de87eea | 265 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 266 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
9de87eea | 267 | SCM_STACKITEM *dst = thread->continuation_base; |
01c8a3dd DH |
268 | SCM_STACKITEM stack_top_element; |
269 | ||
4ccb2cd2 | 270 | #if SCM_STACK_GROWS_UP |
5afcf08b | 271 | if (dst + continuation->num_stack_items >= &stack_top_element) |
01c8a3dd | 272 | grow_stack (cont, val); |
0f2d19dd | 273 | #else |
5f144b10 | 274 | dst -= continuation->num_stack_items; |
c8a1bdc4 | 275 | if (dst <= &stack_top_element) |
01c8a3dd | 276 | grow_stack (cont, val); |
0f2d19dd | 277 | #endif /* def SCM_STACK_GROWS_UP */ |
01c8a3dd | 278 | |
5f144b10 GH |
279 | SCM_FLUSH_REGISTER_WINDOWS; |
280 | copy_stack_and_call (continuation, val, dst); | |
0f2d19dd JB |
281 | } |
282 | ||
db4b4ca6 DH |
283 | |
284 | static SCM | |
285 | continuation_apply (SCM cont, SCM args) | |
5f144b10 | 286 | #define FUNC_NAME "continuation_apply" |
0f2d19dd | 287 | { |
9de87eea | 288 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 289 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
5f144b10 | 290 | |
9de87eea | 291 | if (continuation->root != thread->continuation_root) |
5f144b10 | 292 | { |
9de87eea MV |
293 | SCM_MISC_ERROR |
294 | ("invoking continuation would cross continuation barrier: ~A", | |
295 | scm_list_1 (cont)); | |
5f144b10 | 296 | } |
0f2d19dd | 297 | |
ce212434 | 298 | scm_dynthrow (cont, scm_values (args)); |
0f2d19dd JB |
299 | return SCM_UNSPECIFIED; /* not reached */ |
300 | } | |
5f144b10 | 301 | #undef FUNC_NAME |
0f2d19dd | 302 | |
9de87eea MV |
303 | SCM |
304 | scm_i_with_continuation_barrier (scm_t_catch_body body, | |
305 | void *body_data, | |
306 | scm_t_catch_handler handler, | |
307 | void *handler_data) | |
308 | { | |
309 | SCM_STACKITEM stack_item; | |
310 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
311 | SCM old_controot; | |
312 | SCM_STACKITEM *old_contbase; | |
313 | scm_t_debug_frame *old_lastframe; | |
314 | SCM result; | |
315 | ||
316 | /* Establish a fresh continuation root. | |
317 | */ | |
318 | old_controot = thread->continuation_root; | |
319 | old_contbase = thread->continuation_base; | |
320 | old_lastframe = thread->last_debug_frame; | |
321 | thread->continuation_root = scm_cons (thread->handle, old_controot); | |
322 | thread->continuation_base = &stack_item; | |
323 | thread->last_debug_frame = NULL; | |
324 | ||
325 | /* Call FUNC inside a catch all. This is now guaranteed to return | |
326 | directly and exactly once. | |
327 | */ | |
328 | result = scm_internal_catch (SCM_BOOL_T, | |
329 | body, body_data, | |
330 | handler, handler_data); | |
331 | ||
332 | /* Return to old continuation root. | |
333 | */ | |
334 | thread->last_debug_frame = old_lastframe; | |
335 | thread->continuation_base = old_contbase; | |
336 | thread->continuation_root = old_controot; | |
337 | ||
338 | return result; | |
339 | } | |
340 | ||
341 | struct c_data { | |
342 | void *(*func) (void *); | |
343 | void *data; | |
344 | void *result; | |
345 | }; | |
346 | ||
347 | static SCM | |
348 | c_body (void *d) | |
349 | { | |
350 | struct c_data *data = (struct c_data *)d; | |
351 | data->result = data->func (data->data); | |
352 | return SCM_UNSPECIFIED; | |
353 | } | |
354 | ||
355 | static SCM | |
356 | c_handler (void *d, SCM tag, SCM args) | |
357 | { | |
358 | struct c_data *data = (struct c_data *)d; | |
359 | scm_handle_by_message_noexit (NULL, tag, args); | |
360 | data->result = NULL; | |
361 | return SCM_UNSPECIFIED; | |
362 | } | |
363 | ||
364 | void * | |
365 | scm_c_with_continuation_barrier (void *(*func) (void *), void *data) | |
366 | { | |
367 | struct c_data c_data; | |
368 | c_data.func = func; | |
369 | c_data.data = data; | |
370 | scm_i_with_continuation_barrier (c_body, &c_data, | |
371 | c_handler, &c_data); | |
372 | return c_data.result; | |
373 | } | |
374 | ||
375 | struct scm_data { | |
376 | SCM proc; | |
377 | }; | |
378 | ||
379 | static SCM | |
380 | scm_body (void *d) | |
381 | { | |
382 | struct scm_data *data = (struct scm_data *)d; | |
383 | return scm_call_0 (data->proc); | |
384 | } | |
385 | ||
386 | static SCM | |
387 | scm_handler (void *d, SCM tag, SCM args) | |
388 | { | |
389 | scm_handle_by_message_noexit (NULL, tag, args); | |
390 | return SCM_BOOL_F; | |
391 | } | |
392 | ||
393 | SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0, | |
394 | (SCM proc), | |
69d2000d MV |
395 | "Call @var{proc} and return its result. Do not allow the invocation of\n" |
396 | "continuations that would leave or enter the dynamic extent of the call\n" | |
397 | "to @code{with-continuation-barrier}. Such an attempt causes an error\n" | |
398 | "to be signaled.\n" | |
399 | "\n" | |
400 | "Throws (such as errors) that are not caught from within @var{proc} are\n" | |
401 | "caught by @code{with-continuation-barrier}. In that case, a short\n" | |
402 | "message is printed to the current error port and @code{#f} is returned.\n" | |
403 | "\n" | |
404 | "Thus, @code{with-continuation-barrier} returns exactly once.\n") | |
9de87eea MV |
405 | #define FUNC_NAME s_scm_with_continuation_barrier |
406 | { | |
407 | struct scm_data scm_data; | |
408 | scm_data.proc = proc; | |
409 | return scm_i_with_continuation_barrier (scm_body, &scm_data, | |
410 | scm_handler, &scm_data); | |
411 | } | |
412 | #undef FUNC_NAME | |
db4b4ca6 | 413 | |
0f2d19dd JB |
414 | void |
415 | scm_init_continuations () | |
0f2d19dd | 416 | { |
5f144b10 GH |
417 | scm_tc16_continuation = scm_make_smob_type ("continuation", 0); |
418 | scm_set_smob_mark (scm_tc16_continuation, continuation_mark); | |
419 | scm_set_smob_free (scm_tc16_continuation, continuation_free); | |
420 | scm_set_smob_print (scm_tc16_continuation, continuation_print); | |
421 | scm_set_smob_apply (scm_tc16_continuation, continuation_apply, 0, 0, 1); | |
a0599745 | 422 | #include "libguile/continuations.x" |
0f2d19dd JB |
423 | } |
424 | ||
89e00824 ML |
425 | /* |
426 | Local Variables: | |
427 | c-file-style: "gnu" | |
428 | End: | |
429 | */ |