summaryrefslogtreecommitdiff
path: root/libguile/continuations.c
diff options
context:
space:
mode:
Diffstat (limited to 'libguile/continuations.c')
-rw-r--r--libguile/continuations.c227
1 files changed, 227 insertions, 0 deletions
diff --git a/libguile/continuations.c b/libguile/continuations.c
new file mode 100644
index 000000000..054ed8e56
--- /dev/null
+++ b/libguile/continuations.c
@@ -0,0 +1,227 @@
+/* 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.
+ */
+
+
+#include <stdio.h>
+#include "_scm.h"
+
+
+
+/* {Continuations}
+ */
+
+static char s_cont[] = "continuation";
+
+#ifdef __STDC__
+SCM
+scm_make_cont (SCM * answer)
+#else
+SCM
+scm_make_cont (answer)
+ SCM * answer;
+#endif
+{
+ 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) = 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;
+
+ {
+ SCM winds;
+
+ for (winds = scm_dynwinds; winds != SCM_EOL; winds = SCM_CDR (winds))
+ {
+#if 0
+ 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) = last_debug_info_frame;
+#endif
+ return cont;
+}
+
+
+void scm_dynthrow SCM_P ((SCM *a));
+
+/* Grow the stack so that there is room */
+/* to copy in the continuation. Then */
+#ifndef CHEAP_CONTINUATIONS
+#ifdef __STDC__
+static void
+grow_throw (SCM *a)
+#else
+static void
+grow_throw (a)
+ SCM *a;
+#endif
+{ /* 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 */
+
+#ifdef __STDC__
+void
+scm_dynthrow (SCM *a)
+#else
+void
+scm_dynthrow (a)
+ SCM *a;
+#endif
+{
+ 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
+ last_debug_info_frame = SCM_DFRAME (cont);
+#endif
+ SCM_THROW_VALUE(cont) = val;
+ longjmp (SCM_JMPBUF (cont), 1);
+}
+
+#ifdef __STDC__
+SCM
+scm_call_continuation (SCM cont, SCM val)
+#else
+SCM
+scm_call_continuation (cont, val)
+ SCM cont;
+ SCM val;
+#endif
+{
+ 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 */
+}
+
+
+#ifdef __STDC__
+void
+scm_init_continuations (void)
+#else
+void
+scm_init_continuations ()
+#endif
+{
+#include "continuations.x"
+}
+