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-rw-r--r--libguile/dynstack.h206
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diff --git a/libguile/dynstack.h b/libguile/dynstack.h
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+++ b/libguile/dynstack.h
@@ -0,0 +1,206 @@
+/* classes: h_files */
+
+#ifndef SCM_DYNSTACK_H
+#define SCM_DYNSTACK_H
+
+/* Copyright (C) 2012 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 3 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
+ */
+
+
+
+#include "libguile/__scm.h"
+#include "libguile/control.h"
+
+
+
+typedef struct
+{
+ scm_t_bits *base;
+ scm_t_bits *top;
+ scm_t_bits *limit;
+} scm_t_dynstack;
+
+
+
+/* Items on the dynstack are preceded by two-word headers, giving the
+ offset of the preceding item (or 0 if there is none) and the type,
+ flags, and length of the following dynstack entry, in words. In
+ addition, there is a "null header" at the top of the stack,
+ indicating the length of the previous item, but with a tag of zero.
+
+ For example, consider an empty dynstack, with a capacity of 6 words:
+
+ +----------+----------+ +
+ |prev=0 |tag=0 | |
+ +----------+----------+ +
+ ^base ^top limit^
+
+ Now we evaluate (dynamic-wind enter thunk leave). That will result
+ in a dynstack of:
+
+ / the len=2 words \
+ +----------+----------+----------+----------+----------+----------+
+ |prev=0 |tag:len=2 |enter |leave |prev=4 |tag=0 |
+ +----------+----------+----------+----------+----------+----------+
+ ^base top,limit^
+
+ The tag is a combination of the type of the dynstack item, some flags
+ associated with the item, and the length of the item. See
+ SCM_MAKE_DYNSTACK_TAG below for the details.
+
+ This arrangement makes it possible to have variable-length dynstack
+ items, and yet be able to traverse them forwards or backwards. */
+
+#define SCM_DYNSTACK_HEADER_LEN 2
+
+#define SCM_DYNSTACK_PREV_OFFSET(top) ((top)[-2])
+#define SCM_DYNSTACK_SET_PREV_OFFSET(top, offset) (top)[-2] = (offset)
+
+#define SCM_DYNSTACK_TAG(top) ((top)[-1])
+#define SCM_DYNSTACK_SET_TAG(top, tag) (top)[-1] = (tag)
+
+typedef enum {
+ SCM_DYNSTACK_TYPE_NONE = 0,
+ SCM_DYNSTACK_TYPE_FRAME,
+ SCM_DYNSTACK_TYPE_UNWINDER,
+ SCM_DYNSTACK_TYPE_REWINDER,
+ SCM_DYNSTACK_TYPE_WITH_FLUIDS,
+ SCM_DYNSTACK_TYPE_PROMPT,
+ SCM_DYNSTACK_TYPE_DYNWIND,
+} scm_t_dynstack_item_type;
+
+#define SCM_DYNSTACK_TAG_TYPE_MASK 0xf
+#define SCM_DYNSTACK_TAG_FLAGS_MASK 0xf0
+#define SCM_DYNSTACK_TAG_FLAGS_SHIFT 4
+#define SCM_DYNSTACK_TAG_LEN_SHIFT 8
+
+#define SCM_MAKE_DYNSTACK_TAG(type, flags, len) \
+ ((type) | (flags) | ((len) << SCM_DYNSTACK_TAG_LEN_SHIFT))
+
+#define SCM_DYNSTACK_TAG_TYPE(tag) \
+ ((tag) & SCM_DYNSTACK_TAG_TYPE_MASK)
+#define SCM_DYNSTACK_TAG_FLAGS(tag) \
+ ((tag) & SCM_DYNSTACK_TAG_FLAGS_MASK)
+#define SCM_DYNSTACK_TAG_LEN(tag) \
+ ((tag) >> SCM_DYNSTACK_TAG_LEN_SHIFT)
+
+#define SCM_DYNSTACK_PREV(top) \
+ (SCM_DYNSTACK_PREV_OFFSET (top) \
+ ? ((top) - SCM_DYNSTACK_PREV_OFFSET (top)) : NULL)
+#define SCM_DYNSTACK_NEXT(top) \
+ (SCM_DYNSTACK_TAG (top) \
+ ? ((top) + SCM_DYNSTACK_TAG_LEN (SCM_DYNSTACK_TAG (top)) \
+ + SCM_DYNSTACK_HEADER_LEN) \
+ : NULL)
+
+#define SCM_DYNSTACK_FIRST(dynstack) \
+ ((dynstack)->base + SCM_DYNSTACK_HEADER_LEN)
+
+#define SCM_DYNSTACK_CAPACITY(dynstack) \
+ ((dynstack)->limit - (dynstack)->base)
+#define SCM_DYNSTACK_SPACE(dynstack) \
+ ((dynstack)->limit - (dynstack)->top)
+#define SCM_DYNSTACK_HEIGHT(dynstack) \
+ ((dynstack)->top - (dynstack)->base)
+
+#define SCM_DYNSTACK_HAS_SPACE(dynstack, n) \
+ (SCM_DYNSTACK_SPACE (dynstack) >= n + SCM_DYNSTACK_HEADER_LEN)
+
+typedef enum {
+ SCM_F_DYNSTACK_FRAME_REWINDABLE = (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT)
+} scm_t_dynstack_frame_flags;
+
+typedef enum {
+ SCM_F_DYNSTACK_WINDER_EXPLICIT = (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT)
+} scm_t_dynstack_winder_flags;
+
+typedef enum {
+ SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY = (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT)
+} scm_t_dynstack_prompt_flags;
+
+typedef void (*scm_t_guard) (void *);
+
+
+
+
+/* Pushing and popping entries on the dynamic stack. */
+
+SCM_INTERNAL void scm_dynstack_push_frame (scm_t_dynstack *,
+ scm_t_dynstack_frame_flags);
+SCM_INTERNAL void scm_dynstack_push_rewinder (scm_t_dynstack *,
+ scm_t_dynstack_winder_flags,
+ scm_t_guard, void *);
+SCM_INTERNAL void scm_dynstack_push_unwinder (scm_t_dynstack *,
+ scm_t_dynstack_winder_flags,
+ scm_t_guard, void *);
+SCM_INTERNAL void scm_dynstack_push_fluids (scm_t_dynstack *,
+ size_t,
+ SCM *fluids,
+ SCM *values,
+ SCM dynamic_state);
+SCM_INTERNAL void scm_dynstack_push_prompt (scm_t_dynstack *,
+ scm_t_dynstack_prompt_flags,
+ SCM key,
+ scm_t_prompt_registers *);
+SCM_INTERNAL void scm_dynstack_push_dynwind (scm_t_dynstack *,
+ SCM enter, SCM leave);
+
+SCM_INTERNAL void scm_dynstack_pop (scm_t_dynstack *);
+
+
+
+
+/* Capturing, winding, and unwinding. */
+
+SCM_INTERNAL scm_t_dynstack* scm_dynstack_capture_all (scm_t_dynstack *dynstack);
+SCM_INTERNAL scm_t_dynstack* scm_dynstack_capture (scm_t_dynstack *dynstack,
+ scm_t_bits *item);
+
+SCM_INTERNAL void scm_dynstack_wind_1 (scm_t_dynstack *, scm_t_bits *);
+SCM_INTERNAL scm_t_bits scm_dynstack_unwind_1 (scm_t_dynstack *);
+
+SCM_INTERNAL void scm_dynstack_wind (scm_t_dynstack *, scm_t_bits *);
+SCM_INTERNAL void scm_dynstack_unwind (scm_t_dynstack *, scm_t_bits *);
+
+SCM_INTERNAL scm_t_bits* scm_dynstack_unwind_fork (scm_t_dynstack *,
+ scm_t_dynstack *);
+
+SCM_INTERNAL void scm_dynstack_unwind_frame (scm_t_dynstack *);
+SCM_INTERNAL void scm_dynstack_unwind_fluids (scm_t_dynstack *dynstack,
+ SCM dynamic_state);
+
+
+
+
+/* Miscellany. */
+
+SCM_INTERNAL scm_t_bits* scm_dynstack_find_prompt (scm_t_dynstack *, SCM,
+ scm_t_prompt_registers **,
+ scm_t_dynstack_prompt_flags *);
+
+SCM_INTERNAL scm_t_prompt_registers*
+scm_dynstack_relocate_prompt (scm_t_dynstack *, scm_t_ptrdiff, scm_t_uint64);
+
+
+#endif /* SCM_DYNSTACK_H */
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/