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/* classes: h_files */
#ifndef SCM_DYNSTACK_H
#define SCM_DYNSTACK_H
/* Copyright (C) 2012, 2013 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"
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_FLUID,
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_F_DYNSTACK_PROMPT_PUSH_NARGS = (2 << 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_fluid (scm_t_dynstack *,
SCM fluid, SCM value,
SCM dynamic_state);
SCM_INTERNAL void scm_dynstack_push_prompt (scm_t_dynstack *,
scm_t_dynstack_prompt_flags,
SCM key,
scm_t_ptrdiff fp_offset,
scm_t_ptrdiff sp_offset,
scm_t_uint32 *ip,
scm_i_jmp_buf *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 *);
/* Miscellany. */
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_fluid (scm_t_dynstack *dynstack,
SCM dynamic_state);
SCM_INTERNAL scm_t_bits* scm_dynstack_find_prompt (scm_t_dynstack *, SCM,
scm_t_dynstack_prompt_flags *,
scm_t_ptrdiff *,
scm_t_ptrdiff *,
scm_t_uint32 **,
scm_i_jmp_buf **);
SCM_INTERNAL void scm_dynstack_wind_prompt (scm_t_dynstack *, scm_t_bits *,
scm_t_ptrdiff, scm_i_jmp_buf *);
#endif /* SCM_DYNSTACK_H */
/*
Local Variables:
c-file-style: "gnu"
End:
*/
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