Commit | Line | Data |
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1d1cae0e | 1 | /* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006, 2008, 2009, 2010 Free Software Foundation, Inc. |
0f2d19dd | 2 | * |
73be1d9e | 3 | * This library is free software; you can redistribute it and/or |
53befeb7 NJ |
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. | |
0f2d19dd | 7 | * |
53befeb7 NJ |
8 | * This library is distributed in the hope that it will be useful, but |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
73be1d9e MV |
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 | |
53befeb7 NJ |
15 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
16 | * 02110-1301 USA | |
73be1d9e | 17 | */ |
1bbd0b84 | 18 | |
1bbd0b84 | 19 | |
0f2d19dd | 20 | \f |
dbb605f5 LC |
21 | #ifdef HAVE_CONFIG_H |
22 | # include <config.h> | |
23 | #endif | |
0f2d19dd | 24 | |
bbd43f03 RB |
25 | #include "libguile/_scm.h" |
26 | ||
13070bd3 | 27 | #include <string.h> |
8b7f0bb3 | 28 | #include <stdio.h> |
13070bd3 | 29 | |
8b7f0bb3 | 30 | #include "libguile/async.h" |
d0f6ceb8 | 31 | #include "libguile/debug.h" |
a0599745 MD |
32 | #include "libguile/root.h" |
33 | #include "libguile/stackchk.h" | |
5f144b10 GH |
34 | #include "libguile/smob.h" |
35 | #include "libguile/ports.h" | |
36 | #include "libguile/dynwind.h" | |
9de87eea | 37 | #include "libguile/eval.h" |
bfffd258 | 38 | #include "libguile/vm.h" |
1d1cae0e | 39 | #include "libguile/instructions.h" |
5f144b10 | 40 | |
db4b4ca6 | 41 | #include "libguile/validate.h" |
a0599745 | 42 | #include "libguile/continuations.h" |
01c8a3dd | 43 | |
0f2d19dd JB |
44 | \f |
45 | ||
1d1cae0e AW |
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) | |
1d1cae0e AW |
56 | #define SCM_CONTINUATION_ROOT(x) ((SCM_CONTREGS (x))->root) |
57 | #define SCM_DFRAME(x) ((SCM_CONTREGS (x))->dframe) | |
58 | ||
59 | \f | |
60 | ||
997659f8 | 61 | /* scm_i_make_continuation will return a procedure whose objcode contains an |
1d1cae0e AW |
62 | instruction to reinstate the continuation. Here, as in gsubr.c and smob.c, we |
63 | define the form of that trampoline function. | |
0f2d19dd JB |
64 | */ |
65 | ||
1d1cae0e | 66 | #ifdef WORDS_BIGENDIAN |
babfc7b2 AW |
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 | |
1d1cae0e | 69 | #else |
babfc7b2 AW |
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 | |
1d1cae0e AW |
72 | #endif |
73 | ||
74 | #define ROUND_UP(len,align) (((len-1)|(align-1))+1) | |
75 | #define ALIGN_PTR(type,p,align) (type*)(ROUND_UP (((scm_t_bits)p), align)) | |
76 | ||
77 | #ifdef SCM_ALIGNED | |
78 | #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym)\ | |
79 | static const type sym[] | |
80 | #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym)\ | |
81 | static SCM_ALIGNED (alignment) const type sym[] | |
82 | #else | |
83 | #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym)\ | |
84 | static type *sym | |
85 | #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym) \ | |
86 | SCM_SNARF_INIT(sym = scm_malloc (sizeof(sym##__unaligned) + alignment - 1); \ | |
87 | sym = ALIGN_PTR (type, sym, alignment); \ | |
88 | memcpy (sym, sym##__unaligned, sizeof(sym##__unaligned));) \ | |
89 | static type *sym = NULL; \ | |
90 | static const type sym##__unaligned[] | |
91 | #endif | |
92 | ||
93 | #define STATIC_OBJCODE_TAG \ | |
94 | SCM_PACK (scm_tc7_objcode | (SCM_F_OBJCODE_IS_STATIC << 8)) | |
95 | ||
96 | #define SCM_STATIC_OBJCODE(sym) \ | |
97 | SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode); \ | |
98 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = { \ | |
99 | { STATIC_OBJCODE_TAG, SCM_PACK (sym##__bytecode) }, \ | |
100 | { SCM_BOOL_F, SCM_PACK (0) } \ | |
101 | }; \ | |
102 | static const SCM sym = SCM_PACK (sym##__cells); \ | |
103 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode) | |
104 | ||
105 | ||
106 | SCM_STATIC_OBJCODE (cont_objcode) = { | |
107 | /* This code is the same as in gsubr.c, except we use smob_call instead of | |
108 | struct_call. */ | |
babfc7b2 | 109 | OBJCODE_HEADER (8, 19), |
1d1cae0e AW |
110 | /* leave args on the stack */ |
111 | /* 0 */ scm_op_object_ref, 0, /* push scm_t_contregs smob */ | |
112 | /* 2 */ scm_op_continuation_call, /* and longjmp (whee) */ | |
113 | /* 3 */ scm_op_nop, /* pad to 8 bytes */ | |
114 | /* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop, | |
115 | /* 8 */ | |
116 | ||
117 | /* We could put some meta-info to say that this proc is a continuation. Not sure | |
118 | how to do that, though. */ | |
babfc7b2 | 119 | META_HEADER (19), |
1d1cae0e AW |
120 | /* 0 */ scm_op_make_eol, /* bindings */ |
121 | /* 1 */ scm_op_make_eol, /* sources */ | |
122 | /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */ | |
123 | /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */ | |
124 | /* 7 */ scm_op_make_int8_0, /* 0 optionals */ | |
125 | /* 8 */ scm_op_make_true, /* and a rest arg */ | |
126 | /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */ | |
127 | /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ | |
128 | /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ | |
129 | /* 18 */ scm_op_return /* and return */ | |
130 | /* 19 */ | |
131 | }; | |
132 | ||
133 | ||
babfc7b2 AW |
134 | SCM_STATIC_OBJCODE (call_cc_objcode) = { |
135 | /* Before Scheme's call/cc is compiled, eval.c will use this hand-coded | |
136 | call/cc. */ | |
137 | OBJCODE_HEADER (8, 17), | |
138 | /* 0 */ scm_op_assert_nargs_ee, 0, 1, /* assert that nargs==1 */ | |
139 | /* 3 */ scm_op_local_ref, 0, /* push the proc */ | |
140 | /* 5 */ scm_op_tail_call_cc, /* and call/cc */ | |
141 | /* 6 */ scm_op_nop, scm_op_nop, /* pad to 8 bytes */ | |
142 | /* 8 */ | |
143 | ||
144 | META_HEADER (17), | |
145 | /* 0 */ scm_op_make_eol, /* bindings */ | |
146 | /* 1 */ scm_op_make_eol, /* sources */ | |
147 | /* 2 */ scm_op_make_int8, 3, scm_op_make_int8, 6, /* arity: from ip 0 to ip 6 */ | |
148 | /* 6 */ scm_op_make_int8_1, /* the arity is 0 required args */ | |
149 | /* 7 */ scm_op_list, 0, 3, /* make a list of those 5 vals */ | |
150 | /* 10 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ | |
151 | /* 13 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ | |
152 | /* 16 */ scm_op_return /* and return */ | |
153 | /* 17 */ | |
154 | }; | |
155 | ||
156 | ||
1d1cae0e AW |
157 | static SCM |
158 | make_continuation_trampoline (SCM contregs) | |
159 | { | |
160 | SCM ret = scm_make_program (cont_objcode, | |
161 | scm_c_make_vector (1, contregs), | |
162 | SCM_BOOL_F); | |
163 | SCM_SET_CELL_WORD_0 (ret, | |
164 | SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_CONTINUATION); | |
165 | ||
166 | return ret; | |
167 | } | |
168 | ||
169 | ||
170 | /* {Continuations} | |
171 | */ | |
0f2d19dd | 172 | |
01c8a3dd | 173 | |
e841c3e0 | 174 | static int |
e81d98ec | 175 | continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED) |
5f144b10 | 176 | { |
92c2555f | 177 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
5f144b10 GH |
178 | |
179 | scm_puts ("#<continuation ", port); | |
180 | scm_intprint (continuation->num_stack_items, 10, port); | |
181 | scm_puts (" @ ", port); | |
0236bc68 | 182 | scm_uintprint (SCM_SMOB_DATA_1 (obj), 16, port); |
5f144b10 GH |
183 | scm_putc ('>', port); |
184 | return 1; | |
185 | } | |
1cc91f1b | 186 | |
5f144b10 | 187 | /* this may return more than once: the first time with the escape |
d8873dfe AW |
188 | procedure, then subsequently with SCM_UNDEFINED (the vals already having been |
189 | placed on the VM stack). */ | |
997659f8 | 190 | #define FUNC_NAME "scm_i_make_continuation" |
0f2d19dd | 191 | SCM |
269479e3 | 192 | scm_i_make_continuation (int *first, SCM vm, SCM vm_cont) |
0f2d19dd | 193 | { |
9de87eea MV |
194 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
195 | SCM cont; | |
92c2555f | 196 | scm_t_contregs *continuation; |
c014a02e | 197 | long stack_size; |
01c8a3dd | 198 | SCM_STACKITEM * src; |
0f2d19dd | 199 | |
0f2d19dd | 200 | SCM_FLUSH_REGISTER_WINDOWS; |
9de87eea | 201 | stack_size = scm_stack_size (thread->continuation_base); |
4c9419ac MV |
202 | continuation = scm_gc_malloc (sizeof (scm_t_contregs) |
203 | + (stack_size - 1) * sizeof (SCM_STACKITEM), | |
204 | "continuation"); | |
5f144b10 | 205 | continuation->num_stack_items = stack_size; |
9de87eea | 206 | continuation->dynenv = scm_i_dynwinds (); |
9de87eea | 207 | continuation->root = thread->continuation_root; |
9de87eea | 208 | src = thread->continuation_base; |
4ccb2cd2 | 209 | #if ! SCM_STACK_GROWS_UP |
5f144b10 GH |
210 | src -= stack_size; |
211 | #endif | |
5c5c27dc | 212 | continuation->offset = continuation->stack - src; |
5f144b10 | 213 | memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size); |
269479e3 AW |
214 | continuation->vm = vm; |
215 | continuation->vm_cont = vm_cont; | |
5f144b10 | 216 | |
1d1cae0e | 217 | SCM_NEWSMOB (cont, tc16_continuation, continuation); |
79824460 | 218 | |
a4dbe1ac | 219 | *first = !SCM_I_SETJMP (continuation->jmpbuf); |
346e4402 | 220 | if (*first) |
193297d8 | 221 | { |
346e4402 | 222 | #ifdef __ia64__ |
9a5fa6e9 | 223 | continuation->backing_store_size = |
346e4402 | 224 | (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx) |
9a5fa6e9 | 225 | - |
346e4402 | 226 | (char *) thread->register_backing_store_base; |
193297d8 RB |
227 | continuation->backing_store = NULL; |
228 | continuation->backing_store = | |
4c9419ac MV |
229 | scm_gc_malloc (continuation->backing_store_size, |
230 | "continuation backing store"); | |
193297d8 | 231 | memcpy (continuation->backing_store, |
346e4402 | 232 | (void *) thread->register_backing_store_base, |
193297d8 | 233 | continuation->backing_store_size); |
346e4402 | 234 | #endif /* __ia64__ */ |
1d1cae0e | 235 | return make_continuation_trampoline (cont); |
193297d8 RB |
236 | } |
237 | else | |
d8873dfe | 238 | return SCM_UNDEFINED; |
0f2d19dd | 239 | } |
5f144b10 | 240 | #undef FUNC_NAME |
0f2d19dd | 241 | |
babfc7b2 AW |
242 | SCM |
243 | scm_i_call_with_current_continuation (SCM proc) | |
244 | { | |
245 | static SCM call_cc = SCM_BOOL_F; | |
246 | ||
247 | if (scm_is_false (call_cc)) | |
248 | call_cc = scm_make_program (call_cc_objcode, SCM_BOOL_F, SCM_BOOL_F); | |
249 | ||
250 | return scm_call_1 (call_cc, proc); | |
251 | } | |
252 | ||
1d1cae0e AW |
253 | SCM |
254 | scm_i_continuation_to_frame (SCM continuation) | |
255 | { | |
256 | SCM contregs; | |
257 | scm_t_contregs *cont; | |
258 | ||
259 | contregs = scm_c_vector_ref (scm_program_objects (continuation), 0); | |
260 | cont = SCM_CONTREGS (contregs); | |
261 | ||
269479e3 | 262 | if (scm_is_true (cont->vm_cont)) |
1d1cae0e | 263 | { |
269479e3 AW |
264 | struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont); |
265 | return scm_c_make_frame (cont->vm_cont, | |
1d1cae0e AW |
266 | data->fp + data->reloc, |
267 | data->sp + data->reloc, | |
d8873dfe | 268 | data->ra, |
1d1cae0e AW |
269 | data->reloc); |
270 | } | |
271 | else | |
272 | return SCM_BOOL_F; | |
273 | } | |
274 | ||
d8873dfe AW |
275 | SCM |
276 | scm_i_contregs_vm (SCM contregs) | |
277 | { | |
278 | return SCM_CONTREGS (contregs)->vm; | |
279 | } | |
280 | ||
281 | SCM | |
282 | scm_i_contregs_vm_cont (SCM contregs) | |
283 | { | |
284 | return SCM_CONTREGS (contregs)->vm_cont; | |
285 | } | |
286 | ||
1d1cae0e AW |
287 | |
288 | /* {Apply} | |
289 | */ | |
d3c6aef9 MV |
290 | |
291 | /* Invoking a continuation proceeds as follows: | |
292 | * | |
293 | * - the stack is made large enough for the called continuation | |
294 | * - the old windchain is unwound down to the branching point | |
295 | * - the continuation stack is copied into place | |
296 | * - the windchain is rewound up to the continuation's context | |
297 | * - the continuation is invoked via longjmp (or setcontext) | |
298 | * | |
299 | * This order is important so that unwind and rewind handlers are run | |
300 | * with their correct stack. | |
301 | */ | |
302 | ||
d8873dfe | 303 | static void scm_dynthrow (SCM); |
01c8a3dd DH |
304 | |
305 | /* Grow the stack by a fixed amount to provide space to copy in the | |
306 | * continuation. Possibly this function has to be called several times | |
307 | * recursively before enough space is available. Make sure the compiler does | |
308 | * not optimize the growth array away by storing it's address into a global | |
309 | * variable. | |
310 | */ | |
311 | ||
92c2555f | 312 | scm_t_bits scm_i_dummy; |
1cc91f1b | 313 | |
0f2d19dd | 314 | static void |
d8873dfe | 315 | grow_stack (SCM cont) |
01c8a3dd | 316 | { |
92c2555f | 317 | scm_t_bits growth[100]; |
01c8a3dd | 318 | |
92c2555f | 319 | scm_i_dummy = (scm_t_bits) growth; |
d8873dfe | 320 | scm_dynthrow (cont); |
0f2d19dd | 321 | } |
0f2d19dd | 322 | |
1cc91f1b | 323 | |
01c8a3dd DH |
324 | /* Copy the continuation stack into the current stack. Calling functions from |
325 | * within this function is safe, since only stack frames below this function's | |
326 | * own frame are overwritten. Thus, memcpy can be used for best performance. | |
327 | */ | |
d3c6aef9 MV |
328 | |
329 | typedef struct { | |
330 | scm_t_contregs *continuation; | |
331 | SCM_STACKITEM *dst; | |
332 | } copy_stack_data; | |
333 | ||
01c8a3dd | 334 | static void |
d3c6aef9 MV |
335 | copy_stack (void *data) |
336 | { | |
337 | copy_stack_data *d = (copy_stack_data *)data; | |
338 | memcpy (d->dst, d->continuation->stack, | |
339 | sizeof (SCM_STACKITEM) * d->continuation->num_stack_items); | |
346e4402 NJ |
340 | #ifdef __ia64__ |
341 | SCM_I_CURRENT_THREAD->pending_rbs_continuation = d->continuation; | |
342 | #endif | |
d3c6aef9 MV |
343 | } |
344 | ||
345 | static void | |
d8873dfe | 346 | copy_stack_and_call (scm_t_contregs *continuation, |
5f144b10 | 347 | SCM_STACKITEM * dst) |
0f2d19dd | 348 | { |
d3c6aef9 MV |
349 | long delta; |
350 | copy_stack_data data; | |
351 | ||
9de87eea | 352 | delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv); |
d3c6aef9 MV |
353 | data.continuation = continuation; |
354 | data.dst = dst; | |
14578fa4 | 355 | scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data); |
01c8a3dd | 356 | |
a4dbe1ac | 357 | SCM_I_LONGJMP (continuation->jmpbuf, 1); |
01c8a3dd DH |
358 | } |
359 | ||
346e4402 NJ |
360 | #ifdef __ia64__ |
361 | void | |
a4dbe1ac | 362 | scm_ia64_longjmp (scm_i_jmp_buf *JB, int VAL) |
346e4402 NJ |
363 | { |
364 | scm_i_thread *t = SCM_I_CURRENT_THREAD; | |
365 | ||
366 | if (t->pending_rbs_continuation) | |
367 | { | |
368 | memcpy (t->register_backing_store_base, | |
369 | t->pending_rbs_continuation->backing_store, | |
370 | t->pending_rbs_continuation->backing_store_size); | |
371 | t->pending_rbs_continuation = NULL; | |
372 | } | |
373 | setcontext (&JB->ctx); | |
374 | } | |
375 | #endif | |
376 | ||
01c8a3dd DH |
377 | /* Call grow_stack until the stack space is large enough, then, as the current |
378 | * stack frame might get overwritten, let copy_stack_and_call perform the | |
379 | * actual copying and continuation calling. | |
380 | */ | |
381 | static void | |
d8873dfe | 382 | scm_dynthrow (SCM cont) |
01c8a3dd | 383 | { |
9de87eea | 384 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 385 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
9de87eea | 386 | SCM_STACKITEM *dst = thread->continuation_base; |
01c8a3dd DH |
387 | SCM_STACKITEM stack_top_element; |
388 | ||
87f30eda | 389 | if (thread->critical_section_level) |
8b7f0bb3 MV |
390 | { |
391 | fprintf (stderr, "continuation invoked from within critical section.\n"); | |
392 | abort (); | |
393 | } | |
394 | ||
4ccb2cd2 | 395 | #if SCM_STACK_GROWS_UP |
5afcf08b | 396 | if (dst + continuation->num_stack_items >= &stack_top_element) |
d8873dfe | 397 | grow_stack (cont); |
0f2d19dd | 398 | #else |
5f144b10 | 399 | dst -= continuation->num_stack_items; |
c8a1bdc4 | 400 | if (dst <= &stack_top_element) |
d8873dfe | 401 | grow_stack (cont); |
0f2d19dd | 402 | #endif /* def SCM_STACK_GROWS_UP */ |
01c8a3dd | 403 | |
5f144b10 | 404 | SCM_FLUSH_REGISTER_WINDOWS; |
d8873dfe | 405 | copy_stack_and_call (continuation, dst); |
0f2d19dd JB |
406 | } |
407 | ||
db4b4ca6 | 408 | |
1d1cae0e | 409 | void |
d8873dfe | 410 | scm_i_check_continuation (SCM cont) |
0f2d19dd | 411 | { |
9de87eea | 412 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 413 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
5f144b10 | 414 | |
9de87eea | 415 | if (continuation->root != thread->continuation_root) |
1d1cae0e AW |
416 | scm_misc_error |
417 | ("%continuation-call", | |
418 | "invoking continuation would cross continuation barrier: ~A", | |
419 | scm_list_1 (cont)); | |
d8873dfe AW |
420 | } |
421 | ||
422 | void | |
423 | scm_i_reinstate_continuation (SCM cont) | |
424 | { | |
425 | scm_dynthrow (cont); | |
0f2d19dd | 426 | } |
0f2d19dd | 427 | |
9de87eea MV |
428 | SCM |
429 | scm_i_with_continuation_barrier (scm_t_catch_body body, | |
430 | void *body_data, | |
431 | scm_t_catch_handler handler, | |
43e01b1e NJ |
432 | void *handler_data, |
433 | scm_t_catch_handler pre_unwind_handler, | |
434 | void *pre_unwind_handler_data) | |
9de87eea MV |
435 | { |
436 | SCM_STACKITEM stack_item; | |
437 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
438 | SCM old_controot; | |
439 | SCM_STACKITEM *old_contbase; | |
9de87eea MV |
440 | SCM result; |
441 | ||
442 | /* Establish a fresh continuation root. | |
443 | */ | |
444 | old_controot = thread->continuation_root; | |
445 | old_contbase = thread->continuation_base; | |
9de87eea MV |
446 | thread->continuation_root = scm_cons (thread->handle, old_controot); |
447 | thread->continuation_base = &stack_item; | |
9de87eea MV |
448 | |
449 | /* Call FUNC inside a catch all. This is now guaranteed to return | |
450 | directly and exactly once. | |
451 | */ | |
43e01b1e NJ |
452 | result = scm_c_catch (SCM_BOOL_T, |
453 | body, body_data, | |
454 | handler, handler_data, | |
455 | pre_unwind_handler, pre_unwind_handler_data); | |
9de87eea MV |
456 | |
457 | /* Return to old continuation root. | |
458 | */ | |
9de87eea MV |
459 | thread->continuation_base = old_contbase; |
460 | thread->continuation_root = old_controot; | |
461 | ||
462 | return result; | |
463 | } | |
464 | ||
465 | struct c_data { | |
466 | void *(*func) (void *); | |
467 | void *data; | |
468 | void *result; | |
469 | }; | |
470 | ||
471 | static SCM | |
472 | c_body (void *d) | |
473 | { | |
474 | struct c_data *data = (struct c_data *)d; | |
475 | data->result = data->func (data->data); | |
476 | return SCM_UNSPECIFIED; | |
477 | } | |
478 | ||
479 | static SCM | |
480 | c_handler (void *d, SCM tag, SCM args) | |
481 | { | |
482 | struct c_data *data = (struct c_data *)d; | |
9de87eea MV |
483 | data->result = NULL; |
484 | return SCM_UNSPECIFIED; | |
485 | } | |
486 | ||
487 | void * | |
488 | scm_c_with_continuation_barrier (void *(*func) (void *), void *data) | |
489 | { | |
490 | struct c_data c_data; | |
491 | c_data.func = func; | |
492 | c_data.data = data; | |
493 | scm_i_with_continuation_barrier (c_body, &c_data, | |
43e01b1e NJ |
494 | c_handler, &c_data, |
495 | scm_handle_by_message_noexit, NULL); | |
9de87eea MV |
496 | return c_data.result; |
497 | } | |
498 | ||
499 | struct scm_data { | |
500 | SCM proc; | |
501 | }; | |
502 | ||
503 | static SCM | |
504 | scm_body (void *d) | |
505 | { | |
506 | struct scm_data *data = (struct scm_data *)d; | |
507 | return scm_call_0 (data->proc); | |
508 | } | |
509 | ||
510 | static SCM | |
511 | scm_handler (void *d, SCM tag, SCM args) | |
512 | { | |
9de87eea MV |
513 | return SCM_BOOL_F; |
514 | } | |
515 | ||
516 | SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0, | |
517 | (SCM proc), | |
69d2000d MV |
518 | "Call @var{proc} and return its result. Do not allow the invocation of\n" |
519 | "continuations that would leave or enter the dynamic extent of the call\n" | |
520 | "to @code{with-continuation-barrier}. Such an attempt causes an error\n" | |
521 | "to be signaled.\n" | |
522 | "\n" | |
523 | "Throws (such as errors) that are not caught from within @var{proc} are\n" | |
524 | "caught by @code{with-continuation-barrier}. In that case, a short\n" | |
525 | "message is printed to the current error port and @code{#f} is returned.\n" | |
526 | "\n" | |
527 | "Thus, @code{with-continuation-barrier} returns exactly once.\n") | |
9de87eea MV |
528 | #define FUNC_NAME s_scm_with_continuation_barrier |
529 | { | |
530 | struct scm_data scm_data; | |
531 | scm_data.proc = proc; | |
532 | return scm_i_with_continuation_barrier (scm_body, &scm_data, | |
43e01b1e NJ |
533 | scm_handler, &scm_data, |
534 | scm_handle_by_message_noexit, NULL); | |
9de87eea MV |
535 | } |
536 | #undef FUNC_NAME | |
db4b4ca6 | 537 | |
0f2d19dd JB |
538 | void |
539 | scm_init_continuations () | |
0f2d19dd | 540 | { |
1d1cae0e AW |
541 | tc16_continuation = scm_make_smob_type ("continuation", 0); |
542 | scm_set_smob_print (tc16_continuation, continuation_print); | |
a0599745 | 543 | #include "libguile/continuations.x" |
0f2d19dd JB |
544 | } |
545 | ||
89e00824 ML |
546 | /* |
547 | Local Variables: | |
548 | c-file-style: "gnu" | |
549 | End: | |
550 | */ |