-/* Copyright (C) 1995,1996 Free Software Foundation, Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this software; see the file COPYING. If not, write to
- * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- * As a special exception, the Free Software Foundation gives permission
- * for additional uses of the text contained in its release of GUILE.
- *
- * The exception is that, if you link the GUILE library with other files
- * to produce an executable, this does not by itself cause the
- * resulting executable to be covered by the GNU General Public License.
- * Your use of that executable is in no way restricted on account of
- * linking the GUILE library code into it.
- *
- * This exception does not however invalidate any other reasons why
- * the executable file might be covered by the GNU General Public License.
- *
- * This exception applies only to the code released by the
- * Free Software Foundation under the name GUILE. If you copy
- * code from other Free Software Foundation releases into a copy of
- * GUILE, as the General Public License permits, the exception does
- * not apply to the code that you add in this way. To avoid misleading
- * anyone as to the status of such modified files, you must delete
- * this exception notice from them.
- *
- * If you write modifications of your own for GUILE, it is your choice
- * whether to permit this exception to apply to your modifications.
- * If you do not wish that, delete this exception notice.
- */
-\f
-
-#include <stdio.h>
-#include "_scm.h"
-#include "stackchk.h"
-#ifdef DEBUG_EXTENSIONS
-#include "debug.h"
-#endif
-#include "dynwind.h"
-
-#include "continuations.h"
-\f
-
-/* {Continuations}
- */
-
-static char s_cont[] = "continuation";
-
-
-SCM
-scm_make_cont (answer)
- SCM * answer;
-{
- long j;
- SCM cont;
-
-#ifdef CHEAP_CONTINUATIONS
- SCM_NEWCELL (cont);
- *answer = cont;
- SCM_DEFER_INTS;
- SCM_SETJMPBUF (cont, scm_must_malloc ((long) sizeof (regs), s_cont));
- SCM_CAR (cont) = scm_tc7_contin;
- SCM_DYNENV (cont) = scm_dynwinds;
- SCM_THROW_VALUE = SCM_EOL;
- SCM_BASE (cont) = SCM_BASE (rootcont);
- SCM_SEQ (cont) = SCM_SEQ (rootcont);
- SCM_ALLOW_INTS;
-#else
- register SCM_STACKITEM *src, *dst;
-
-#if 0
- {
- SCM winds;
-
- for (winds = scm_dynwinds; winds != SCM_EOL; winds = SCM_CDR (winds))
- {
- if (SCM_INUMP (SCM_CAR (winds)))
- {
- scm_relocate_chunk_to_heap (SCM_CAR (winds));
- }
- }
- }
-#endif
-
- SCM_NEWCELL (cont);
- *answer = cont;
- SCM_DEFER_INTS;
- SCM_FLUSH_REGISTER_WINDOWS;
- j = scm_stack_size (SCM_BASE (scm_rootcont));
- SCM_SETJMPBUF (cont,
- scm_must_malloc ((long) (sizeof (regs) + j * sizeof (SCM_STACKITEM)),
- s_cont));
- SCM_SETLENGTH (cont, j, scm_tc7_contin);
- SCM_DYNENV (cont) = scm_dynwinds;
- SCM_THROW_VALUE (cont) = SCM_EOL;
- src = SCM_BASE (cont) = SCM_BASE (scm_rootcont);
- SCM_SEQ (cont) = SCM_SEQ (scm_rootcont);
- SCM_ALLOW_INTS;
-#ifndef SCM_STACK_GROWS_UP
- src -= SCM_LENGTH (cont);
-#endif /* ndef SCM_STACK_GROWS_UP */
- dst = (SCM_STACKITEM *) (SCM_CHARS (cont) + sizeof (regs));
- for (j = SCM_LENGTH (cont); 0 <= --j;)
- *dst++ = *src++;
-#endif /* def CHEAP_CONTINUATIONS */
-#ifdef DEBUG_EXTENSIONS
- SCM_DFRAME (cont) = scm_last_debug_frame;
-#endif
- return cont;
-}
-
-/* Grow the stack so that there is room */
-/* to copy in the continuation. Then */
-#ifndef CHEAP_CONTINUATIONS
-
-static void grow_throw SCM_P ((SCM *a));
-
-static void
-grow_throw (a)
- SCM *a;
-{ /* retry the throw. */
- SCM growth[100];
- growth[0] = a[0];
- growth[1] = a[1];
- growth[2] = a[2] + 1;
- growth[3] = (SCM) a;
- scm_dynthrow (growth);
-}
-#endif /* ndef CHEAP_CONTINUATIONS */
-
-
-void
-scm_dynthrow (a)
- SCM *a;
-{
- SCM cont = a[0], val = a[1];
-#ifndef CHEAP_CONTINUATIONS
- register long j;
- register SCM_STACKITEM *src, *dst = SCM_BASE (scm_rootcont);
-#ifdef SCM_STACK_GROWS_UP
- if (a[2] && (a - ((SCM *) a[3]) < 100))
-#else
- if (a[2] && (((SCM *) a[3]) - a < 100))
-#endif
- fputs ("grow_throw: check if SCM growth[100]; being optimized out\n",
- stderr);
- /* if (a[2]) fprintf(stderr, " ct = %ld, dist = %ld\n",
- a[2], (((SCM *)a[3]) - a)); */
-#ifdef SCM_STACK_GROWS_UP
- if (SCM_PTR_GE (dst + SCM_LENGTH (cont), (SCM_STACKITEM *) & a))
- grow_throw (a);
-#else
- dst -= SCM_LENGTH (cont);
- if (SCM_PTR_LE (dst, (SCM_STACKITEM *) & a))
- grow_throw (a);
-#endif /* def SCM_STACK_GROWS_UP */
- SCM_FLUSH_REGISTER_WINDOWS;
- src = (SCM_STACKITEM *) (SCM_CHARS (cont) + sizeof (regs));
- for (j = SCM_LENGTH (cont); 0 <= --j;)
- *dst++ = *src++;
-#ifdef sparc /* clear out stack up to this stackframe */
- /* maybe this would help, maybe not */
-/* bzero((void *)&a, sizeof(SCM_STACKITEM) * (((SCM_STACKITEM *)&a) -
- (dst - SCM_LENGTH(cont)))) */
-#endif
-#endif /* ndef CHEAP_CONTINUATIONS */
-#ifdef DEBUG_EXTENSIONS
- scm_last_debug_frame = SCM_DFRAME (cont);
-#endif
- SCM_THROW_VALUE(cont) = val;
- longjmp (SCM_JMPBUF (cont), 1);
-}
-
-
-SCM
-scm_call_continuation (cont, val)
- SCM cont;
- SCM val;
-{
- SCM a[3];
- a[0] = cont;
- a[1] = val;
- a[2] = 0;
- if ( (SCM_SEQ (cont) != SCM_SEQ (scm_rootcont))
- || (SCM_BASE (cont) != SCM_BASE (scm_rootcont))) /* base compare not needed */
- scm_wta (cont, "continuation from wrong top level", s_cont);
-
- scm_dowinds (SCM_DYNENV (cont),
- scm_ilength (scm_dynwinds) - scm_ilength (SCM_DYNENV (cont)));
-
- scm_dynthrow (a);
- return SCM_UNSPECIFIED; /* not reached */
-}
-
-
-
-void
-scm_init_continuations ()
-{
-#include "continuations.x"
-}
-
+/* Copyright (C) 1995,1996,1998,2000,2001,2004, 2006, 2008 Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+\f
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libguile/_scm.h"
+
+#include <string.h>
+#include <stdio.h>
+
+#include "libguile/async.h"
+#include "libguile/debug.h"
+#include "libguile/root.h"
+#include "libguile/stackchk.h"
+#include "libguile/smob.h"
+#include "libguile/ports.h"
+#include "libguile/dynwind.h"
+#include "libguile/values.h"
+#include "libguile/eval.h"
+#include "libguile/vm.h"
+
+#include "libguile/validate.h"
+#include "libguile/continuations.h"
+
+\f
+
+/* {Continuations}
+ */
+
+scm_t_bits scm_tc16_continuation;
+
+static SCM
+continuation_mark (SCM obj)
+{
+ scm_t_contregs *continuation = SCM_CONTREGS (obj);
+
+ scm_gc_mark (continuation->root);
+ scm_gc_mark (continuation->throw_value);
+ scm_gc_mark (continuation->vm_conts);
+ scm_mark_locations (continuation->stack, continuation->num_stack_items);
+#ifdef __ia64__
+ if (continuation->backing_store)
+ scm_mark_locations (continuation->backing_store,
+ continuation->backing_store_size /
+ sizeof (SCM_STACKITEM));
+#endif /* __ia64__ */
+ return continuation->dynenv;
+}
+
+static size_t
+continuation_free (SCM obj)
+{
+ scm_t_contregs *continuation = SCM_CONTREGS (obj);
+ /* stack array size is 1 if num_stack_items is 0. */
+ size_t extra_items = (continuation->num_stack_items > 0)
+ ? (continuation->num_stack_items - 1)
+ : 0;
+ size_t bytes_free = sizeof (scm_t_contregs)
+ + extra_items * sizeof (SCM_STACKITEM);
+
+#ifdef __ia64__
+ scm_gc_free (continuation->backing_store, continuation->backing_store_size,
+ "continuation backing store");
+#endif /* __ia64__ */
+ scm_gc_free (continuation, bytes_free, "continuation");
+ return 0;
+}
+
+static int
+continuation_print (SCM obj, SCM port, scm_print_state *state SCM_UNUSED)
+{
+ scm_t_contregs *continuation = SCM_CONTREGS (obj);
+
+ scm_puts ("#<continuation ", port);
+ scm_intprint (continuation->num_stack_items, 10, port);
+ scm_puts (" @ ", port);
+ scm_uintprint (SCM_CELL_WORD_1 (obj), 16, port);
+ scm_putc ('>', port);
+ return 1;
+}
+
+/* this may return more than once: the first time with the escape
+ procedure, then subsequently with the value to be passed to the
+ continuation. */
+#define FUNC_NAME "scm_make_continuation"
+SCM
+scm_make_continuation (int *first)
+{
+ scm_i_thread *thread = SCM_I_CURRENT_THREAD;
+ SCM cont;
+ scm_t_contregs *continuation;
+ long stack_size;
+ SCM_STACKITEM * src;
+
+ SCM_FLUSH_REGISTER_WINDOWS;
+ stack_size = scm_stack_size (thread->continuation_base);
+ continuation = scm_gc_malloc (sizeof (scm_t_contregs)
+ + (stack_size - 1) * sizeof (SCM_STACKITEM),
+ "continuation");
+ continuation->num_stack_items = stack_size;
+ continuation->dynenv = scm_i_dynwinds ();
+ continuation->throw_value = SCM_EOL;
+ continuation->root = thread->continuation_root;
+ continuation->dframe = scm_i_last_debug_frame ();
+ src = thread->continuation_base;
+ SCM_NEWSMOB (cont, scm_tc16_continuation, continuation);
+
+#if ! SCM_STACK_GROWS_UP
+ src -= stack_size;
+#endif
+ continuation->offset = continuation->stack - src;
+ memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size);
+ continuation->vm_conts = scm_vm_capture_continuations ();
+
+ *first = !setjmp (continuation->jmpbuf);
+ if (*first)
+ {
+#ifdef __ia64__
+ continuation->backing_store_size =
+ (char *) scm_ia64_ar_bsp(&continuation->jmpbuf.ctx)
+ -
+ (char *) thread->register_backing_store_base;
+ continuation->backing_store = NULL;
+ continuation->backing_store =
+ scm_gc_malloc (continuation->backing_store_size,
+ "continuation backing store");
+ memcpy (continuation->backing_store,
+ (void *) thread->register_backing_store_base,
+ continuation->backing_store_size);
+#endif /* __ia64__ */
+ return cont;
+ }
+ else
+ {
+ SCM ret = continuation->throw_value;
+ continuation->throw_value = SCM_BOOL_F;
+ return ret;
+ }
+}
+#undef FUNC_NAME
+
+
+/* Invoking a continuation proceeds as follows:
+ *
+ * - the stack is made large enough for the called continuation
+ * - the old windchain is unwound down to the branching point
+ * - the continuation stack is copied into place
+ * - the windchain is rewound up to the continuation's context
+ * - the continuation is invoked via longjmp (or setcontext)
+ *
+ * This order is important so that unwind and rewind handlers are run
+ * with their correct stack.
+ */
+
+static void scm_dynthrow (SCM, SCM);
+
+/* Grow the stack by a fixed amount to provide space to copy in the
+ * continuation. Possibly this function has to be called several times
+ * recursively before enough space is available. Make sure the compiler does
+ * not optimize the growth array away by storing it's address into a global
+ * variable.
+ */
+
+scm_t_bits scm_i_dummy;
+
+static void
+grow_stack (SCM cont, SCM val)
+{
+ scm_t_bits growth[100];
+
+ scm_i_dummy = (scm_t_bits) growth;
+ scm_dynthrow (cont, val);
+}
+
+
+/* Copy the continuation stack into the current stack. Calling functions from
+ * within this function is safe, since only stack frames below this function's
+ * own frame are overwritten. Thus, memcpy can be used for best performance.
+ */
+
+typedef struct {
+ scm_t_contregs *continuation;
+ SCM_STACKITEM *dst;
+} copy_stack_data;
+
+static void
+copy_stack (void *data)
+{
+ copy_stack_data *d = (copy_stack_data *)data;
+ memcpy (d->dst, d->continuation->stack,
+ sizeof (SCM_STACKITEM) * d->continuation->num_stack_items);
+ scm_vm_reinstate_continuations (d->continuation->vm_conts);
+#ifdef __ia64__
+ SCM_I_CURRENT_THREAD->pending_rbs_continuation = d->continuation;
+#endif
+}
+
+static void
+copy_stack_and_call (scm_t_contregs *continuation, SCM val,
+ SCM_STACKITEM * dst)
+{
+ long delta;
+ copy_stack_data data;
+
+ delta = scm_ilength (scm_i_dynwinds ()) - scm_ilength (continuation->dynenv);
+ data.continuation = continuation;
+ data.dst = dst;
+ scm_i_dowinds (continuation->dynenv, delta, copy_stack, &data);
+
+ scm_i_set_last_debug_frame (continuation->dframe);
+
+ continuation->throw_value = val;
+ longjmp (continuation->jmpbuf, 1);
+}
+
+#ifdef __ia64__
+void
+scm_ia64_longjmp (jmp_buf *JB, int VAL)
+{
+ scm_i_thread *t = SCM_I_CURRENT_THREAD;
+
+ if (t->pending_rbs_continuation)
+ {
+ memcpy (t->register_backing_store_base,
+ t->pending_rbs_continuation->backing_store,
+ t->pending_rbs_continuation->backing_store_size);
+ t->pending_rbs_continuation = NULL;
+ }
+ setcontext (&JB->ctx);
+}
+#endif
+
+/* Call grow_stack until the stack space is large enough, then, as the current
+ * stack frame might get overwritten, let copy_stack_and_call perform the
+ * actual copying and continuation calling.
+ */
+static void
+scm_dynthrow (SCM cont, SCM val)
+{
+ scm_i_thread *thread = SCM_I_CURRENT_THREAD;
+ scm_t_contregs *continuation = SCM_CONTREGS (cont);
+ SCM_STACKITEM *dst = thread->continuation_base;
+ SCM_STACKITEM stack_top_element;
+
+ if (scm_i_critical_section_level)
+ {
+ fprintf (stderr, "continuation invoked from within critical section.\n");
+ abort ();
+ }
+
+#if SCM_STACK_GROWS_UP
+ if (dst + continuation->num_stack_items >= &stack_top_element)
+ grow_stack (cont, val);
+#else
+ dst -= continuation->num_stack_items;
+ if (dst <= &stack_top_element)
+ grow_stack (cont, val);
+#endif /* def SCM_STACK_GROWS_UP */
+
+ SCM_FLUSH_REGISTER_WINDOWS;
+ copy_stack_and_call (continuation, val, dst);
+}
+
+
+static SCM
+continuation_apply (SCM cont, SCM args)
+#define FUNC_NAME "continuation_apply"
+{
+ scm_i_thread *thread = SCM_I_CURRENT_THREAD;
+ scm_t_contregs *continuation = SCM_CONTREGS (cont);
+
+ if (continuation->root != thread->continuation_root)
+ {
+ SCM_MISC_ERROR
+ ("invoking continuation would cross continuation barrier: ~A",
+ scm_list_1 (cont));
+ }
+
+ scm_dynthrow (cont, scm_values (args));
+ return SCM_UNSPECIFIED; /* not reached */
+}
+#undef FUNC_NAME
+
+SCM
+scm_i_with_continuation_barrier (scm_t_catch_body body,
+ void *body_data,
+ scm_t_catch_handler handler,
+ void *handler_data,
+ scm_t_catch_handler pre_unwind_handler,
+ void *pre_unwind_handler_data)
+{
+ SCM_STACKITEM stack_item;
+ scm_i_thread *thread = SCM_I_CURRENT_THREAD;
+ SCM old_controot;
+ SCM_STACKITEM *old_contbase;
+ scm_t_debug_frame *old_lastframe;
+ SCM result;
+
+ /* Establish a fresh continuation root.
+ */
+ old_controot = thread->continuation_root;
+ old_contbase = thread->continuation_base;
+ old_lastframe = thread->last_debug_frame;
+ thread->continuation_root = scm_cons (thread->handle, old_controot);
+ thread->continuation_base = &stack_item;
+ thread->last_debug_frame = NULL;
+
+ /* Call FUNC inside a catch all. This is now guaranteed to return
+ directly and exactly once.
+ */
+ result = scm_c_catch (SCM_BOOL_T,
+ body, body_data,
+ handler, handler_data,
+ pre_unwind_handler, pre_unwind_handler_data);
+
+ /* Return to old continuation root.
+ */
+ thread->last_debug_frame = old_lastframe;
+ thread->continuation_base = old_contbase;
+ thread->continuation_root = old_controot;
+
+ return result;
+}
+
+struct c_data {
+ void *(*func) (void *);
+ void *data;
+ void *result;
+};
+
+static SCM
+c_body (void *d)
+{
+ struct c_data *data = (struct c_data *)d;
+ data->result = data->func (data->data);
+ return SCM_UNSPECIFIED;
+}
+
+static SCM
+c_handler (void *d, SCM tag, SCM args)
+{
+ struct c_data *data = (struct c_data *)d;
+ data->result = NULL;
+ return SCM_UNSPECIFIED;
+}
+
+void *
+scm_c_with_continuation_barrier (void *(*func) (void *), void *data)
+{
+ struct c_data c_data;
+ c_data.func = func;
+ c_data.data = data;
+ scm_i_with_continuation_barrier (c_body, &c_data,
+ c_handler, &c_data,
+ scm_handle_by_message_noexit, NULL);
+ return c_data.result;
+}
+
+struct scm_data {
+ SCM proc;
+};
+
+static SCM
+scm_body (void *d)
+{
+ struct scm_data *data = (struct scm_data *)d;
+ return scm_call_0 (data->proc);
+}
+
+static SCM
+scm_handler (void *d, SCM tag, SCM args)
+{
+ return SCM_BOOL_F;
+}
+
+SCM_DEFINE (scm_with_continuation_barrier, "with-continuation-barrier", 1,0,0,
+ (SCM proc),
+"Call @var{proc} and return its result. Do not allow the invocation of\n"
+"continuations that would leave or enter the dynamic extent of the call\n"
+"to @code{with-continuation-barrier}. Such an attempt causes an error\n"
+"to be signaled.\n"
+"\n"
+"Throws (such as errors) that are not caught from within @var{proc} are\n"
+"caught by @code{with-continuation-barrier}. In that case, a short\n"
+"message is printed to the current error port and @code{#f} is returned.\n"
+"\n"
+"Thus, @code{with-continuation-barrier} returns exactly once.\n")
+#define FUNC_NAME s_scm_with_continuation_barrier
+{
+ struct scm_data scm_data;
+ scm_data.proc = proc;
+ return scm_i_with_continuation_barrier (scm_body, &scm_data,
+ scm_handler, &scm_data,
+ scm_handle_by_message_noexit, NULL);
+}
+#undef FUNC_NAME
+
+void
+scm_init_continuations ()
+{
+ scm_tc16_continuation = scm_make_smob_type ("continuation", 0);
+ scm_set_smob_mark (scm_tc16_continuation, continuation_mark);
+ scm_set_smob_free (scm_tc16_continuation, continuation_free);
+ scm_set_smob_print (scm_tc16_continuation, continuation_print);
+ scm_set_smob_apply (scm_tc16_continuation, continuation_apply, 0, 0, 1);
+#include "libguile/continuations.x"
+}
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/
HCoop / bpt / guile.git / blobdiff