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" | |
ce212434 | 37 | #include "libguile/values.h" |
9de87eea | 38 | #include "libguile/eval.h" |
bfffd258 | 39 | #include "libguile/vm.h" |
1d1cae0e | 40 | #include "libguile/instructions.h" |
5f144b10 | 41 | |
db4b4ca6 | 42 | #include "libguile/validate.h" |
a0599745 | 43 | #include "libguile/continuations.h" |
01c8a3dd | 44 | |
0f2d19dd JB |
45 | \f |
46 | ||
1d1cae0e AW |
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_DYNENV(x) ((SCM_CONTREGS (x))->dynenv) | |
57 | #define SCM_THROW_VALUE(x) ((SCM_CONTREGS (x))->throw_value) | |
58 | #define SCM_CONTINUATION_ROOT(x) ((SCM_CONTREGS (x))->root) | |
59 | #define SCM_DFRAME(x) ((SCM_CONTREGS (x))->dframe) | |
60 | ||
61 | \f | |
62 | ||
997659f8 | 63 | /* scm_i_make_continuation will return a procedure whose objcode contains an |
1d1cae0e AW |
64 | instruction to reinstate the continuation. Here, as in gsubr.c and smob.c, we |
65 | define the form of that trampoline function. | |
0f2d19dd JB |
66 | */ |
67 | ||
1d1cae0e | 68 | #ifdef WORDS_BIGENDIAN |
babfc7b2 AW |
69 | #define OBJCODE_HEADER(main,meta) 0, 0, 0, main, 0, 0, 0, meta+8 |
70 | #define META_HEADER(meta) 0, 0, 0, meta, 0, 0, 0, 0 | |
1d1cae0e | 71 | #else |
babfc7b2 AW |
72 | #define OBJCODE_HEADER(main,meta) main, 0, 0, 0, meta+8, 0, 0, 0 |
73 | #define META_HEADER(meta) meta, 0, 0, 0, 0, 0, 0, 0 | |
1d1cae0e AW |
74 | #endif |
75 | ||
76 | #define ROUND_UP(len,align) (((len-1)|(align-1))+1) | |
77 | #define ALIGN_PTR(type,p,align) (type*)(ROUND_UP (((scm_t_bits)p), align)) | |
78 | ||
79 | #ifdef SCM_ALIGNED | |
80 | #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym)\ | |
81 | static const type sym[] | |
82 | #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym)\ | |
83 | static SCM_ALIGNED (alignment) const type sym[] | |
84 | #else | |
85 | #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym)\ | |
86 | static type *sym | |
87 | #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym) \ | |
88 | SCM_SNARF_INIT(sym = scm_malloc (sizeof(sym##__unaligned) + alignment - 1); \ | |
89 | sym = ALIGN_PTR (type, sym, alignment); \ | |
90 | memcpy (sym, sym##__unaligned, sizeof(sym##__unaligned));) \ | |
91 | static type *sym = NULL; \ | |
92 | static const type sym##__unaligned[] | |
93 | #endif | |
94 | ||
95 | #define STATIC_OBJCODE_TAG \ | |
96 | SCM_PACK (scm_tc7_objcode | (SCM_F_OBJCODE_IS_STATIC << 8)) | |
97 | ||
98 | #define SCM_STATIC_OBJCODE(sym) \ | |
99 | SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode); \ | |
100 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = { \ | |
101 | { STATIC_OBJCODE_TAG, SCM_PACK (sym##__bytecode) }, \ | |
102 | { SCM_BOOL_F, SCM_PACK (0) } \ | |
103 | }; \ | |
104 | static const SCM sym = SCM_PACK (sym##__cells); \ | |
105 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode) | |
106 | ||
107 | ||
108 | SCM_STATIC_OBJCODE (cont_objcode) = { | |
109 | /* This code is the same as in gsubr.c, except we use smob_call instead of | |
110 | struct_call. */ | |
babfc7b2 | 111 | OBJCODE_HEADER (8, 19), |
1d1cae0e AW |
112 | /* leave args on the stack */ |
113 | /* 0 */ scm_op_object_ref, 0, /* push scm_t_contregs smob */ | |
114 | /* 2 */ scm_op_continuation_call, /* and longjmp (whee) */ | |
115 | /* 3 */ scm_op_nop, /* pad to 8 bytes */ | |
116 | /* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop, | |
117 | /* 8 */ | |
118 | ||
119 | /* We could put some meta-info to say that this proc is a continuation. Not sure | |
120 | how to do that, though. */ | |
babfc7b2 | 121 | META_HEADER (19), |
1d1cae0e AW |
122 | /* 0 */ scm_op_make_eol, /* bindings */ |
123 | /* 1 */ scm_op_make_eol, /* sources */ | |
124 | /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */ | |
125 | /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */ | |
126 | /* 7 */ scm_op_make_int8_0, /* 0 optionals */ | |
127 | /* 8 */ scm_op_make_true, /* and a rest arg */ | |
128 | /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */ | |
129 | /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ | |
130 | /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ | |
131 | /* 18 */ scm_op_return /* and return */ | |
132 | /* 19 */ | |
133 | }; | |
134 | ||
135 | ||
babfc7b2 AW |
136 | SCM_STATIC_OBJCODE (call_cc_objcode) = { |
137 | /* Before Scheme's call/cc is compiled, eval.c will use this hand-coded | |
138 | call/cc. */ | |
139 | OBJCODE_HEADER (8, 17), | |
140 | /* 0 */ scm_op_assert_nargs_ee, 0, 1, /* assert that nargs==1 */ | |
141 | /* 3 */ scm_op_local_ref, 0, /* push the proc */ | |
142 | /* 5 */ scm_op_tail_call_cc, /* and call/cc */ | |
143 | /* 6 */ scm_op_nop, scm_op_nop, /* pad to 8 bytes */ | |
144 | /* 8 */ | |
145 | ||
146 | META_HEADER (17), | |
147 | /* 0 */ scm_op_make_eol, /* bindings */ | |
148 | /* 1 */ scm_op_make_eol, /* sources */ | |
149 | /* 2 */ scm_op_make_int8, 3, scm_op_make_int8, 6, /* arity: from ip 0 to ip 6 */ | |
150 | /* 6 */ scm_op_make_int8_1, /* the arity is 0 required args */ | |
151 | /* 7 */ scm_op_list, 0, 3, /* make a list of those 5 vals */ | |
152 | /* 10 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ | |
153 | /* 13 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ | |
154 | /* 16 */ scm_op_return /* and return */ | |
155 | /* 17 */ | |
156 | }; | |
157 | ||
158 | ||
1d1cae0e AW |
159 | static SCM |
160 | make_continuation_trampoline (SCM contregs) | |
161 | { | |
162 | SCM ret = scm_make_program (cont_objcode, | |
163 | scm_c_make_vector (1, contregs), | |
164 | SCM_BOOL_F); | |
165 | SCM_SET_CELL_WORD_0 (ret, | |
166 | SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_CONTINUATION); | |
167 | ||
168 | return ret; | |
169 | } | |
170 | ||
171 | ||
172 | /* {Continuations} | |
173 | */ | |
0f2d19dd | 174 | |
01c8a3dd | 175 | |
e841c3e0 | 176 | static int |
e81d98ec | 177 | continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED) |
5f144b10 | 178 | { |
92c2555f | 179 | scm_t_contregs *continuation = SCM_CONTREGS (obj); |
5f144b10 GH |
180 | |
181 | scm_puts ("#<continuation ", port); | |
182 | scm_intprint (continuation->num_stack_items, 10, port); | |
183 | scm_puts (" @ ", port); | |
0236bc68 | 184 | scm_uintprint (SCM_SMOB_DATA_1 (obj), 16, port); |
5f144b10 GH |
185 | scm_putc ('>', port); |
186 | return 1; | |
187 | } | |
1cc91f1b | 188 | |
5f144b10 GH |
189 | /* this may return more than once: the first time with the escape |
190 | procedure, then subsequently with the value to be passed to the | |
191 | continuation. */ | |
997659f8 | 192 | #define FUNC_NAME "scm_i_make_continuation" |
0f2d19dd | 193 | SCM |
269479e3 | 194 | scm_i_make_continuation (int *first, SCM vm, SCM vm_cont) |
0f2d19dd | 195 | { |
9de87eea MV |
196 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
197 | SCM cont; | |
92c2555f | 198 | scm_t_contregs *continuation; |
c014a02e | 199 | long stack_size; |
01c8a3dd | 200 | SCM_STACKITEM * src; |
0f2d19dd | 201 | |
0f2d19dd | 202 | SCM_FLUSH_REGISTER_WINDOWS; |
9de87eea | 203 | stack_size = scm_stack_size (thread->continuation_base); |
4c9419ac MV |
204 | continuation = scm_gc_malloc (sizeof (scm_t_contregs) |
205 | + (stack_size - 1) * sizeof (SCM_STACKITEM), | |
206 | "continuation"); | |
5f144b10 | 207 | continuation->num_stack_items = stack_size; |
9de87eea | 208 | continuation->dynenv = scm_i_dynwinds (); |
5f144b10 | 209 | continuation->throw_value = SCM_EOL; |
9de87eea | 210 | continuation->root = thread->continuation_root; |
9de87eea | 211 | src = thread->continuation_base; |
4ccb2cd2 | 212 | #if ! SCM_STACK_GROWS_UP |
5f144b10 GH |
213 | src -= stack_size; |
214 | #endif | |
5c5c27dc | 215 | continuation->offset = continuation->stack - src; |
5f144b10 | 216 | memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size); |
269479e3 AW |
217 | continuation->vm = vm; |
218 | continuation->vm_cont = vm_cont; | |
5f144b10 | 219 | |
1d1cae0e | 220 | SCM_NEWSMOB (cont, tc16_continuation, continuation); |
79824460 | 221 | |
a4dbe1ac | 222 | *first = !SCM_I_SETJMP (continuation->jmpbuf); |
346e4402 | 223 | if (*first) |
193297d8 | 224 | { |
346e4402 | 225 | #ifdef __ia64__ |
9a5fa6e9 | 226 | continuation->backing_store_size = |
346e4402 | 227 | (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx) |
9a5fa6e9 | 228 | - |
346e4402 | 229 | (char *) thread->register_backing_store_base; |
193297d8 RB |
230 | continuation->backing_store = NULL; |
231 | continuation->backing_store = | |
4c9419ac MV |
232 | scm_gc_malloc (continuation->backing_store_size, |
233 | "continuation backing store"); | |
193297d8 | 234 | memcpy (continuation->backing_store, |
346e4402 | 235 | (void *) thread->register_backing_store_base, |
193297d8 | 236 | continuation->backing_store_size); |
346e4402 | 237 | #endif /* __ia64__ */ |
1d1cae0e | 238 | return make_continuation_trampoline (cont); |
193297d8 RB |
239 | } |
240 | else | |
241 | { | |
3c468478 | 242 | SCM ret = continuation->throw_value; |
3c468478 MV |
243 | continuation->throw_value = SCM_BOOL_F; |
244 | return ret; | |
5f144b10 | 245 | } |
0f2d19dd | 246 | } |
5f144b10 | 247 | #undef FUNC_NAME |
0f2d19dd | 248 | |
babfc7b2 AW |
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 | ||
1d1cae0e AW |
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 | ||
269479e3 | 269 | if (scm_is_true (cont->vm_cont)) |
1d1cae0e | 270 | { |
269479e3 AW |
271 | struct scm_vm_cont *data = SCM_VM_CONT_DATA (cont->vm_cont); |
272 | return scm_c_make_frame (cont->vm_cont, | |
1d1cae0e AW |
273 | data->fp + data->reloc, |
274 | data->sp + data->reloc, | |
275 | data->ip, | |
276 | data->reloc); | |
277 | } | |
278 | else | |
279 | return SCM_BOOL_F; | |
280 | } | |
281 | ||
282 | ||
283 | /* {Apply} | |
284 | */ | |
d3c6aef9 MV |
285 | |
286 | /* Invoking a continuation proceeds as follows: | |
287 | * | |
288 | * - the stack is made large enough for the called continuation | |
289 | * - the old windchain is unwound down to the branching point | |
290 | * - the continuation stack is copied into place | |
291 | * - the windchain is rewound up to the continuation's context | |
292 | * - the continuation is invoked via longjmp (or setcontext) | |
293 | * | |
294 | * This order is important so that unwind and rewind handlers are run | |
295 | * with their correct stack. | |
296 | */ | |
297 | ||
5f144b10 | 298 | static void scm_dynthrow (SCM, SCM); |
01c8a3dd DH |
299 | |
300 | /* Grow the stack by a fixed amount to provide space to copy in the | |
301 | * continuation. Possibly this function has to be called several times | |
302 | * recursively before enough space is available. Make sure the compiler does | |
303 | * not optimize the growth array away by storing it's address into a global | |
304 | * variable. | |
305 | */ | |
306 | ||
92c2555f | 307 | scm_t_bits scm_i_dummy; |
1cc91f1b | 308 | |
0f2d19dd | 309 | static void |
01c8a3dd DH |
310 | grow_stack (SCM cont, SCM val) |
311 | { | |
92c2555f | 312 | scm_t_bits growth[100]; |
01c8a3dd | 313 | |
92c2555f | 314 | scm_i_dummy = (scm_t_bits) growth; |
01c8a3dd | 315 | scm_dynthrow (cont, val); |
0f2d19dd | 316 | } |
0f2d19dd | 317 | |
1cc91f1b | 318 | |
01c8a3dd DH |
319 | /* Copy the continuation stack into the current stack. Calling functions from |
320 | * within this function is safe, since only stack frames below this function's | |
321 | * own frame are overwritten. Thus, memcpy can be used for best performance. | |
322 | */ | |
d3c6aef9 MV |
323 | |
324 | typedef struct { | |
325 | scm_t_contregs *continuation; | |
326 | SCM_STACKITEM *dst; | |
327 | } copy_stack_data; | |
328 | ||
01c8a3dd | 329 | static void |
d3c6aef9 MV |
330 | copy_stack (void *data) |
331 | { | |
332 | copy_stack_data *d = (copy_stack_data *)data; | |
333 | memcpy (d->dst, d->continuation->stack, | |
334 | sizeof (SCM_STACKITEM) * d->continuation->num_stack_items); | |
269479e3 AW |
335 | scm_i_vm_reinstate_continuation (d->continuation->vm, |
336 | d->continuation->vm_cont); | |
346e4402 NJ |
337 | #ifdef __ia64__ |
338 | SCM_I_CURRENT_THREAD->pending_rbs_continuation = d->continuation; | |
339 | #endif | |
d3c6aef9 MV |
340 | } |
341 | ||
342 | static void | |
343 | copy_stack_and_call (scm_t_contregs *continuation, SCM val, | |
5f144b10 | 344 | SCM_STACKITEM * dst) |
0f2d19dd | 345 | { |
d3c6aef9 MV |
346 | long delta; |
347 | copy_stack_data data; | |
348 | ||
9de87eea | 349 | delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv); |
d3c6aef9 MV |
350 | data.continuation = continuation; |
351 | data.dst = dst; | |
14578fa4 | 352 | scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data); |
01c8a3dd | 353 | |
5f144b10 | 354 | continuation->throw_value = val; |
a4dbe1ac | 355 | SCM_I_LONGJMP (continuation->jmpbuf, 1); |
01c8a3dd DH |
356 | } |
357 | ||
346e4402 NJ |
358 | #ifdef __ia64__ |
359 | void | |
a4dbe1ac | 360 | scm_ia64_longjmp (scm_i_jmp_buf *JB, int VAL) |
346e4402 NJ |
361 | { |
362 | scm_i_thread *t = SCM_I_CURRENT_THREAD; | |
363 | ||
364 | if (t->pending_rbs_continuation) | |
365 | { | |
366 | memcpy (t->register_backing_store_base, | |
367 | t->pending_rbs_continuation->backing_store, | |
368 | t->pending_rbs_continuation->backing_store_size); | |
369 | t->pending_rbs_continuation = NULL; | |
370 | } | |
371 | setcontext (&JB->ctx); | |
372 | } | |
373 | #endif | |
374 | ||
01c8a3dd DH |
375 | /* Call grow_stack until the stack space is large enough, then, as the current |
376 | * stack frame might get overwritten, let copy_stack_and_call perform the | |
377 | * actual copying and continuation calling. | |
378 | */ | |
379 | static void | |
380 | scm_dynthrow (SCM cont, SCM val) | |
381 | { | |
9de87eea | 382 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 383 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
9de87eea | 384 | SCM_STACKITEM *dst = thread->continuation_base; |
01c8a3dd DH |
385 | SCM_STACKITEM stack_top_element; |
386 | ||
87f30eda | 387 | if (thread->critical_section_level) |
8b7f0bb3 MV |
388 | { |
389 | fprintf (stderr, "continuation invoked from within critical section.\n"); | |
390 | abort (); | |
391 | } | |
392 | ||
4ccb2cd2 | 393 | #if SCM_STACK_GROWS_UP |
5afcf08b | 394 | if (dst + continuation->num_stack_items >= &stack_top_element) |
01c8a3dd | 395 | grow_stack (cont, val); |
0f2d19dd | 396 | #else |
5f144b10 | 397 | dst -= continuation->num_stack_items; |
c8a1bdc4 | 398 | if (dst <= &stack_top_element) |
01c8a3dd | 399 | grow_stack (cont, val); |
0f2d19dd | 400 | #endif /* def SCM_STACK_GROWS_UP */ |
01c8a3dd | 401 | |
5f144b10 GH |
402 | SCM_FLUSH_REGISTER_WINDOWS; |
403 | copy_stack_and_call (continuation, val, dst); | |
0f2d19dd JB |
404 | } |
405 | ||
db4b4ca6 | 406 | |
1d1cae0e AW |
407 | void |
408 | scm_i_continuation_call (SCM cont, size_t n, SCM *argv) | |
0f2d19dd | 409 | { |
9de87eea | 410 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; |
92c2555f | 411 | scm_t_contregs *continuation = SCM_CONTREGS (cont); |
1d1cae0e AW |
412 | SCM args = SCM_EOL; |
413 | ||
414 | /* FIXME: shuffle args on VM stack instead of heap-allocating */ | |
415 | while (n--) | |
416 | args = scm_cons (argv[n], args); | |
5f144b10 | 417 | |
9de87eea | 418 | if (continuation->root != thread->continuation_root) |
1d1cae0e AW |
419 | scm_misc_error |
420 | ("%continuation-call", | |
421 | "invoking continuation would cross continuation barrier: ~A", | |
422 | scm_list_1 (cont)); | |
0f2d19dd | 423 | |
ce212434 | 424 | scm_dynthrow (cont, scm_values (args)); |
0f2d19dd | 425 | } |
0f2d19dd | 426 | |
9de87eea MV |
427 | SCM |
428 | scm_i_with_continuation_barrier (scm_t_catch_body body, | |
429 | void *body_data, | |
430 | scm_t_catch_handler handler, | |
43e01b1e NJ |
431 | void *handler_data, |
432 | scm_t_catch_handler pre_unwind_handler, | |
433 | void *pre_unwind_handler_data) | |
9de87eea MV |
434 | { |
435 | SCM_STACKITEM stack_item; | |
436 | scm_i_thread *thread = SCM_I_CURRENT_THREAD; | |
437 | SCM old_controot; | |
438 | SCM_STACKITEM *old_contbase; | |
9de87eea MV |
439 | SCM result; |
440 | ||
441 | /* Establish a fresh continuation root. | |
442 | */ | |
443 | old_controot = thread->continuation_root; | |
444 | old_contbase = thread->continuation_base; | |
9de87eea MV |
445 | thread->continuation_root = scm_cons (thread->handle, old_controot); |
446 | thread->continuation_base = &stack_item; | |
9de87eea MV |
447 | |
448 | /* Call FUNC inside a catch all. This is now guaranteed to return | |
449 | directly and exactly once. | |
450 | */ | |
43e01b1e NJ |
451 | result = scm_c_catch (SCM_BOOL_T, |
452 | body, body_data, | |
453 | handler, handler_data, | |
454 | pre_unwind_handler, pre_unwind_handler_data); | |
9de87eea MV |
455 | |
456 | /* Return to old continuation root. | |
457 | */ | |
9de87eea MV |
458 | thread->continuation_base = old_contbase; |
459 | thread->continuation_root = old_controot; | |
460 | ||
461 | return result; | |
462 | } | |
463 | ||
464 | struct c_data { | |
465 | void *(*func) (void *); | |
466 | void *data; | |
467 | void *result; | |
468 | }; | |
469 | ||
470 | static SCM | |
471 | c_body (void *d) | |
472 | { | |
473 | struct c_data *data = (struct c_data *)d; | |
474 | data->result = data->func (data->data); | |
475 | return SCM_UNSPECIFIED; | |
476 | } | |
477 | ||
478 | static SCM | |
479 | c_handler (void *d, SCM tag, SCM args) | |
480 | { | |
481 | struct c_data *data = (struct c_data *)d; | |
9de87eea MV |
482 | data->result = NULL; |
483 | return SCM_UNSPECIFIED; | |
484 | } | |
485 | ||
486 | void * | |
487 | scm_c_with_continuation_barrier (void *(*func) (void *), void *data) | |
488 | { | |
489 | struct c_data c_data; | |
490 | c_data.func = func; | |
491 | c_data.data = data; | |
492 | scm_i_with_continuation_barrier (c_body, &c_data, | |
43e01b1e NJ |
493 | c_handler, &c_data, |
494 | scm_handle_by_message_noexit, NULL); | |
9de87eea MV |
495 | return c_data.result; |
496 | } | |
497 | ||
498 | struct scm_data { | |
499 | SCM proc; | |
500 | }; | |
501 | ||
502 | static SCM | |
503 | scm_body (void *d) | |
504 | { | |
505 | struct scm_data *data = (struct scm_data *)d; | |
506 | return scm_call_0 (data->proc); | |
507 | } | |
508 | ||
509 | static SCM | |
510 | scm_handler (void *d, SCM tag, SCM args) | |
511 | { | |
9de87eea MV |
512 | return SCM_BOOL_F; |
513 | } | |
514 | ||
515 | SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0, | |
516 | (SCM proc), | |
69d2000d MV |
517 | "Call @var{proc} and return its result. Do not allow the invocation of\n" |
518 | "continuations that would leave or enter the dynamic extent of the call\n" | |
519 | "to @code{with-continuation-barrier}. Such an attempt causes an error\n" | |
520 | "to be signaled.\n" | |
521 | "\n" | |
522 | "Throws (such as errors) that are not caught from within @var{proc} are\n" | |
523 | "caught by @code{with-continuation-barrier}. In that case, a short\n" | |
524 | "message is printed to the current error port and @code{#f} is returned.\n" | |
525 | "\n" | |
526 | "Thus, @code{with-continuation-barrier} returns exactly once.\n") | |
9de87eea MV |
527 | #define FUNC_NAME s_scm_with_continuation_barrier |
528 | { | |
529 | struct scm_data scm_data; | |
530 | scm_data.proc = proc; | |
531 | return scm_i_with_continuation_barrier (scm_body, &scm_data, | |
43e01b1e NJ |
532 | scm_handler, &scm_data, |
533 | scm_handle_by_message_noexit, NULL); | |
9de87eea MV |
534 | } |
535 | #undef FUNC_NAME | |
db4b4ca6 | 536 | |
0f2d19dd JB |
537 | void |
538 | scm_init_continuations () | |
0f2d19dd | 539 | { |
1d1cae0e AW |
540 | tc16_continuation = scm_make_smob_type ("continuation", 0); |
541 | scm_set_smob_print (tc16_continuation, continuation_print); | |
a0599745 | 542 | #include "libguile/continuations.x" |
0f2d19dd JB |
543 | } |
544 | ||
89e00824 ML |
545 | /* |
546 | Local Variables: | |
547 | c-file-style: "gnu" | |
548 | End: | |
549 | */ |