6 /* Copyright (C) 2012, 2013 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"
39 /* Items on the dynstack are preceded by two-word headers, giving the
40 offset of the preceding item (or 0 if there is none) and the type,
41 flags, and length of the following dynstack entry, in words. In
42 addition, there is a "null header" at the top of the stack,
43 indicating the length of the previous item, but with a tag of zero.
45 For example, consider an empty dynstack, with a capacity of 6 words:
47 +----------+----------+ +
49 +----------+----------+ +
52 Now we evaluate (dynamic-wind enter thunk leave). That will result
56 +----------+----------+----------+----------+----------+----------+
57 |prev=0 |tag:len=2 |enter |leave |prev=4 |tag=0 |
58 +----------+----------+----------+----------+----------+----------+
61 The tag is a combination of the type of the dynstack item, some flags
62 associated with the item, and the length of the item. See
63 SCM_MAKE_DYNSTACK_TAG below for the details.
65 This arrangement makes it possible to have variable-length dynstack
66 items, and yet be able to traverse them forwards or backwards. */
68 #define SCM_DYNSTACK_HEADER_LEN 2
70 #define SCM_DYNSTACK_PREV_OFFSET(top) ((top)[-2])
71 #define SCM_DYNSTACK_SET_PREV_OFFSET(top, offset) (top)[-2] = (offset)
73 #define SCM_DYNSTACK_TAG(top) ((top)[-1])
74 #define SCM_DYNSTACK_SET_TAG(top, tag) (top)[-1] = (tag)
77 SCM_DYNSTACK_TYPE_NONE
= 0,
78 SCM_DYNSTACK_TYPE_FRAME
,
79 SCM_DYNSTACK_TYPE_UNWINDER
,
80 SCM_DYNSTACK_TYPE_REWINDER
,
81 SCM_DYNSTACK_TYPE_WITH_FLUID
,
82 SCM_DYNSTACK_TYPE_PROMPT
,
83 SCM_DYNSTACK_TYPE_DYNWIND
,
84 } scm_t_dynstack_item_type
;
86 #define SCM_DYNSTACK_TAG_TYPE_MASK 0xf
87 #define SCM_DYNSTACK_TAG_FLAGS_MASK 0xf0
88 #define SCM_DYNSTACK_TAG_FLAGS_SHIFT 4
89 #define SCM_DYNSTACK_TAG_LEN_SHIFT 8
91 #define SCM_MAKE_DYNSTACK_TAG(type, flags, len) \
92 ((type) | (flags) | ((len) << SCM_DYNSTACK_TAG_LEN_SHIFT))
94 #define SCM_DYNSTACK_TAG_TYPE(tag) \
95 ((tag) & SCM_DYNSTACK_TAG_TYPE_MASK)
96 #define SCM_DYNSTACK_TAG_FLAGS(tag) \
97 ((tag) & SCM_DYNSTACK_TAG_FLAGS_MASK)
98 #define SCM_DYNSTACK_TAG_LEN(tag) \
99 ((tag) >> SCM_DYNSTACK_TAG_LEN_SHIFT)
101 #define SCM_DYNSTACK_PREV(top) \
102 (SCM_DYNSTACK_PREV_OFFSET (top) \
103 ? ((top) - SCM_DYNSTACK_PREV_OFFSET (top)) : NULL)
104 #define SCM_DYNSTACK_NEXT(top) \
105 (SCM_DYNSTACK_TAG (top) \
106 ? ((top) + SCM_DYNSTACK_TAG_LEN (SCM_DYNSTACK_TAG (top)) \
107 + SCM_DYNSTACK_HEADER_LEN) \
110 #define SCM_DYNSTACK_FIRST(dynstack) \
111 ((dynstack)->base + SCM_DYNSTACK_HEADER_LEN)
113 #define SCM_DYNSTACK_CAPACITY(dynstack) \
114 ((dynstack)->limit - (dynstack)->base)
115 #define SCM_DYNSTACK_SPACE(dynstack) \
116 ((dynstack)->limit - (dynstack)->top)
117 #define SCM_DYNSTACK_HEIGHT(dynstack) \
118 ((dynstack)->top - (dynstack)->base)
120 #define SCM_DYNSTACK_HAS_SPACE(dynstack, n) \
121 (SCM_DYNSTACK_SPACE (dynstack) >= n + SCM_DYNSTACK_HEADER_LEN)
124 SCM_F_DYNSTACK_FRAME_REWINDABLE
= (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT
)
125 } scm_t_dynstack_frame_flags
;
128 SCM_F_DYNSTACK_WINDER_EXPLICIT
= (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT
)
129 } scm_t_dynstack_winder_flags
;
132 SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY
= (1 << SCM_DYNSTACK_TAG_FLAGS_SHIFT
),
133 SCM_F_DYNSTACK_PROMPT_PUSH_NARGS
= (2 << 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_fluid (scm_t_dynstack
*,
152 SCM fluid
, SCM value
,
154 SCM_INTERNAL
void scm_dynstack_push_prompt (scm_t_dynstack
*,
155 scm_t_dynstack_prompt_flags
,
157 scm_t_ptrdiff fp_offset
,
158 scm_t_ptrdiff sp_offset
,
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_fluid (scm_t_dynstack
*dynstack
,
193 SCM_INTERNAL scm_t_bits
* scm_dynstack_find_prompt (scm_t_dynstack
*, SCM
,
194 scm_t_dynstack_prompt_flags
*,
200 SCM_INTERNAL
void scm_dynstack_wind_prompt (scm_t_dynstack
*, scm_t_bits
*,
201 scm_t_ptrdiff
, scm_i_jmp_buf
*);
204 #endif /* SCM_DYNSTACK_H */