6 /* Copyright (C) 2012 Free Software Foundation, Inc.
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public License
10 * as published by the Free Software Foundation; either version 3 of
11 * the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
26 #include "libguile/__scm.h"
27 #include "libguile/control.h"
40 /* Items on the dynstack are preceded by two-word headers, giving the
41 offset of the preceding item (or 0 if there is none) and the type,
42 flags, and length of the following dynstack entry, in words. In
43 addition, there is a "null header" at the top of the stack,
44 indicating the length of the previous item, but with a tag of zero.
46 For example, consider an empty dynstack, with a capacity of 6 words:
48 +----------+----------+ +
50 +----------+----------+ +
53 Now we evaluate (dynamic-wind enter thunk leave). That will result
57 +----------+----------+----------+----------+----------+----------+
58 |prev=0 |tag:len=2 |enter |leave |prev=4 |tag=0 |
59 +----------+----------+----------+----------+----------+----------+
62 The tag is a combination of the type of the dynstack item, some flags
63 associated with the item, and the length of the item. See
64 SCM_MAKE_DYNSTACK_TAG below for the details.
66 This arrangement makes it possible to have variable-length dynstack
67 items, and yet be able to traverse them forwards or backwards. */
69 #define SCM_DYNSTACK_HEADER_LEN 2
71 #define SCM_DYNSTACK_PREV_OFFSET(top) ((top)[-2])
72 #define SCM_DYNSTACK_SET_PREV_OFFSET(top, offset) (top)[-2] = (offset)
74 #define SCM_DYNSTACK_TAG(top) ((top)[-1])
75 #define SCM_DYNSTACK_SET_TAG(top, tag) (top)[-1] = (tag)
78 SCM_DYNSTACK_TYPE_NONE
= 0,
79 SCM_DYNSTACK_TYPE_FRAME
,
80 SCM_DYNSTACK_TYPE_UNWINDER
,
81 SCM_DYNSTACK_TYPE_REWINDER
,
82 SCM_DYNSTACK_TYPE_WITH_FLUIDS
,
83 SCM_DYNSTACK_TYPE_PROMPT
,
84 SCM_DYNSTACK_TYPE_DYNWIND
,
85 } scm_t_dynstack_item_type
;
87 #define SCM_DYNSTACK_TAG_TYPE_MASK 0xf
88 #define SCM_DYNSTACK_TAG_FLAGS_MASK 0xf0
89 #define SCM_DYNSTACK_TAG_FLAGS_SHIFT 4
90 #define SCM_DYNSTACK_TAG_LEN_SHIFT 8
92 #define SCM_MAKE_DYNSTACK_TAG(type, flags, len) \
93 ((type) | (flags) | ((len) << SCM_DYNSTACK_TAG_LEN_SHIFT))
95 #define SCM_DYNSTACK_TAG_TYPE(tag) \
96 ((tag) & SCM_DYNSTACK_TAG_TYPE_MASK)
97 #define SCM_DYNSTACK_TAG_FLAGS(tag) \
98 ((tag) & SCM_DYNSTACK_TAG_FLAGS_MASK)
99 #define SCM_DYNSTACK_TAG_LEN(tag) \
100 ((tag) >> SCM_DYNSTACK_TAG_LEN_SHIFT)
102 #define SCM_DYNSTACK_PREV(top) \
103 (SCM_DYNSTACK_PREV_OFFSET (top) \
104 ? ((top) - SCM_DYNSTACK_PREV_OFFSET (top)) : NULL)
105 #define SCM_DYNSTACK_NEXT(top) \
106 (SCM_DYNSTACK_TAG (top) \
107 ? ((top) + SCM_DYNSTACK_TAG_LEN (SCM_DYNSTACK_TAG (top)) \
108 + SCM_DYNSTACK_HEADER_LEN) \
111 #define SCM_DYNSTACK_FIRST(dynstack) \
112 ((dynstack)->base + SCM_DYNSTACK_HEADER_LEN)
114 #define SCM_DYNSTACK_CAPACITY(dynstack) \
115 ((dynstack)->limit - (dynstack)->base)
116 #define SCM_DYNSTACK_SPACE(dynstack) \
117 ((dynstack)->limit - (dynstack)->top)
118 #define SCM_DYNSTACK_HEIGHT(dynstack) \
119 ((dynstack)->top - (dynstack)->base)
121 #define SCM_DYNSTACK_HAS_SPACE(dynstack, n) \
122 (SCM_DYNSTACK_SPACE (dynstack) >= n + SCM_DYNSTACK_HEADER_LEN)
125 SCM_F_DYNSTACK_FRAME_REWINDABLE
= (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT
)
126 } scm_t_dynstack_frame_flags
;
129 SCM_F_DYNSTACK_WINDER_EXPLICIT
= (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT
)
130 } scm_t_dynstack_winder_flags
;
133 SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY
= (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT
)
134 } scm_t_dynstack_prompt_flags
;
136 typedef void (*scm_t_guard
) (void *);
141 /* Pushing and popping entries on the dynamic stack. */
143 SCM_INTERNAL
void scm_dynstack_push_frame (scm_t_dynstack
*,
144 scm_t_dynstack_frame_flags
);
145 SCM_INTERNAL
void scm_dynstack_push_rewinder (scm_t_dynstack
*,
146 scm_t_dynstack_winder_flags
,
147 scm_t_guard
, void *);
148 SCM_INTERNAL
void scm_dynstack_push_unwinder (scm_t_dynstack
*,
149 scm_t_dynstack_winder_flags
,
150 scm_t_guard
, void *);
151 SCM_INTERNAL
void scm_dynstack_push_fluids (scm_t_dynstack
*,
156 SCM_INTERNAL
void scm_dynstack_push_prompt (scm_t_dynstack
*,
157 scm_t_dynstack_prompt_flags
,
159 SCM
*fp
, SCM
*sp
, scm_t_uint8
*ip
,
160 scm_i_jmp_buf
*registers
);
161 SCM_INTERNAL
void scm_dynstack_push_dynwind (scm_t_dynstack
*,
162 SCM enter
, SCM leave
);
164 SCM_INTERNAL
void scm_dynstack_pop (scm_t_dynstack
*);
169 /* Capturing, winding, and unwinding. */
171 SCM_INTERNAL scm_t_dynstack
* scm_dynstack_capture_all (scm_t_dynstack
*dynstack
);
172 SCM_INTERNAL scm_t_dynstack
* scm_dynstack_capture (scm_t_dynstack
*dynstack
,
175 SCM_INTERNAL
void scm_dynstack_wind_1 (scm_t_dynstack
*, scm_t_bits
*);
176 SCM_INTERNAL scm_t_bits
scm_dynstack_unwind_1 (scm_t_dynstack
*);
178 SCM_INTERNAL
void scm_dynstack_wind (scm_t_dynstack
*, scm_t_bits
*);
179 SCM_INTERNAL
void scm_dynstack_unwind (scm_t_dynstack
*, scm_t_bits
*);
186 SCM_INTERNAL scm_t_bits
* scm_dynstack_unwind_fork (scm_t_dynstack
*,
189 SCM_INTERNAL
void scm_dynstack_unwind_frame (scm_t_dynstack
*);
190 SCM_INTERNAL
void scm_dynstack_unwind_fluids (scm_t_dynstack
*dynstack
,
193 SCM_INTERNAL scm_t_bits
* scm_dynstack_find_prompt (scm_t_dynstack
*, SCM
,
194 scm_t_dynstack_prompt_flags
*,
195 SCM
**, SCM
**, scm_t_uint8
**,
198 SCM_INTERNAL
void scm_dynstack_wind_prompt (scm_t_dynstack
*, scm_t_bits
*,
199 scm_t_ptrdiff
, scm_i_jmp_buf
*);
202 #endif /* SCM_DYNSTACK_H */