1 /* Copyright (C) 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public License
5 * as published by the Free Software Foundation; either version 3 of
6 * the License, or (at your option) any later version.
8 * This library is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
25 #include "libguile/_scm.h"
26 #include "libguile/control.h"
27 #include "libguile/programs.h"
28 #include "libguile/instructions.h"
29 #include "libguile/vm.h"
33 #define PROMPT_ESCAPE_P(p) \
34 (SCM_DYNSTACK_TAG_FLAGS (SCM_DYNSTACK_TAG (p)) \
35 & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY)
40 /* Only to be called if the SCM_I_SETJMP returns 1 */
42 scm_i_prompt_pop_abort_args_x (SCM vm
)
47 n
= scm_to_size_t (SCM_VM_DATA (vm
)->sp
[0]);
48 for (i
= 0; i
< n
; i
++)
49 vals
= scm_cons (SCM_VM_DATA (vm
)->sp
[-(i
+ 1)], vals
);
51 /* The abort did reset the VM's registers, but then these values
52 were pushed on; so we need to pop them ourselves. */
53 SCM_VM_DATA (vm
)->sp
-= n
+ 1;
60 static const scm_t_uint32 compose_continuation_code
[] =
62 SCM_PACK_RTL_24 (scm_rtl_op_compose_continuation
, 0)
67 make_partial_continuation (SCM vm_cont
)
70 scm_t_bits flags
= SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION
;
73 ret
= scm_words (scm_tc7_rtl_program
| (nfree
<< 16) | flags
, nfree
+ 2);
74 SCM_SET_CELL_WORD_1 (ret
, compose_continuation_code
);
75 SCM_RTL_PROGRAM_FREE_VARIABLE_SET (ret
, 0, vm_cont
);
81 reify_partial_continuation (SCM vm
,
82 SCM
*saved_fp
, SCM
*saved_sp
, scm_t_uint8
*saved_ip
,
83 scm_i_jmp_buf
*saved_registers
,
84 scm_t_dynstack
*dynstack
,
85 scm_i_jmp_buf
*current_registers
)
91 flags
= SCM_F_VM_CONT_PARTIAL
;
92 /* If we are aborting to a prompt that has the same registers as those
93 of the abort, it means there are no intervening C frames on the
94 stack, and so the continuation can be relocated elsewhere on the
95 stack: it is rewindable. */
96 if (saved_registers
&& saved_registers
== current_registers
)
97 flags
|= SCM_F_VM_CONT_REWINDABLE
;
99 /* Walk the stack down until we find the first frame after saved_fp.
100 We will save the stack down to that frame. It used to be that we
101 could determine the stack bottom in O(1) time, but that's no longer
102 the case, since the thunk application doesn't occur where the
104 for (bottom_fp
= SCM_VM_DATA (vm
)->fp
;
105 SCM_FRAME_DYNAMIC_LINK (bottom_fp
) > saved_fp
;
106 bottom_fp
= SCM_FRAME_DYNAMIC_LINK (bottom_fp
));
108 if (SCM_FRAME_DYNAMIC_LINK (bottom_fp
) != saved_fp
)
111 /* Capture from the top of the thunk application frame up to the end. */
112 vm_cont
= scm_i_vm_capture_stack (bottom_fp
- 1,
113 SCM_VM_DATA (vm
)->fp
,
114 SCM_VM_DATA (vm
)->sp
,
115 SCM_VM_DATA (vm
)->ip
,
119 return make_partial_continuation (vm_cont
);
123 scm_c_abort (SCM vm
, SCM tag
, size_t n
, SCM
*argv
,
124 scm_i_jmp_buf
*current_registers
)
127 scm_t_dynstack
*dynstack
= &SCM_I_CURRENT_THREAD
->dynstack
;
129 scm_t_dynstack_prompt_flags flags
;
132 scm_i_jmp_buf
*registers
;
135 prompt
= scm_dynstack_find_prompt (dynstack
, tag
,
136 &flags
, &fp
, &sp
, &ip
, ®isters
);
139 scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag
));
141 /* Only reify if the continuation referenced in the handler. */
142 if (flags
& SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY
)
146 scm_t_dynstack
*captured
;
148 captured
= scm_dynstack_capture (dynstack
, SCM_DYNSTACK_NEXT (prompt
));
149 cont
= reify_partial_continuation (vm
, fp
, sp
, ip
, registers
, captured
,
154 scm_dynstack_unwind (dynstack
, prompt
);
156 /* Unwinding may have changed the current thread's VM, so use the
160 /* Restore VM regs */
161 SCM_VM_DATA (vm
)->fp
= fp
;
162 SCM_VM_DATA (vm
)->sp
= sp
;
163 SCM_VM_DATA (vm
)->ip
= ip
;
165 /* Since we're jumping down, we should always have enough space. */
166 if (SCM_VM_DATA (vm
)->sp
+ n
+ 1 >= SCM_VM_DATA (vm
)->stack_limit
)
170 *(++(SCM_VM_DATA (vm
)->sp
)) = cont
;
171 for (i
= 0; i
< n
; i
++)
172 *(++(SCM_VM_DATA (vm
)->sp
)) = argv
[i
];
173 if (flags
& SCM_F_DYNSTACK_PROMPT_PUSH_NARGS
)
174 *(++(SCM_VM_DATA (vm
)->sp
)) = scm_from_size_t (n
+1); /* +1 for continuation */
177 SCM_I_LONGJMP (*registers
, 1);
179 /* Shouldn't get here */
183 SCM_DEFINE (scm_abort_to_prompt_star
, "abort-to-prompt*", 2, 0, 0,
185 "Abort to the nearest prompt with tag @var{tag}, yielding the\n"
186 "values in the list, @var{args}.")
187 #define FUNC_NAME s_scm_abort_to_prompt_star
193 SCM_VALIDATE_LIST_COPYLEN (SCM_ARG2
, args
, n
);
194 argv
= alloca (sizeof (SCM
)*n
);
195 for (i
= 0; i
< n
; i
++, args
= scm_cdr (args
))
196 argv
[i
] = scm_car (args
);
198 scm_c_abort (scm_the_vm (), tag
, n
, argv
, NULL
);
200 /* Oh, what, you're still here? The abort must have been reinstated. Actually,
201 that's quite impossible, given that we're already in C-land here, so...
209 scm_init_control (void)
211 #include "libguile/control.x"