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/* Copyright (C) 2010, 2011, 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
*/
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <alloca.h>
#include "libguile/_scm.h"
#include "libguile/control.h"
#include "libguile/objcodes.h"
#include "libguile/instructions.h"
#include "libguile/vm.h"
#define PROMPT_ESCAPE_P(p) \
(SCM_DYNSTACK_TAG_FLAGS (SCM_DYNSTACK_TAG (p)) \
& SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY)
/* Only to be called if the SCM_I_SETJMP returns 1 */
SCM
scm_i_prompt_pop_abort_args_x (SCM vm)
{
size_t i, n;
SCM vals = SCM_EOL;
n = scm_to_size_t (SCM_VM_DATA (vm)->sp[0]);
for (i = 0; i < n; i++)
vals = scm_cons (SCM_VM_DATA (vm)->sp[-(i + 1)], vals);
/* The abort did reset the VM's registers, but then these values
were pushed on; so we need to pop them ourselves. */
SCM_VM_DATA (vm)->sp -= n + 1;
/* FIXME NULLSTACK */
return vals;
}
#ifdef WORDS_BIGENDIAN
#define OBJCODE_HEADER(main,meta) 0, 0, 0, main, 0, 0, 0, meta+8
#define META_HEADER(meta) 0, 0, 0, meta, 0, 0, 0, 0
#else
#define OBJCODE_HEADER(main,meta) main, 0, 0, 0, meta+8, 0, 0, 0
#define META_HEADER(meta) meta, 0, 0, 0, 0, 0, 0, 0
#endif
#define OBJCODE_TAG SCM_MAKE_OBJCODE_TAG (SCM_OBJCODE_TYPE_STATIC, 0)
#if defined (SCM_ALIGNED)
#define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym) \
static const type sym[]
#define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym) \
static SCM_ALIGNED (alignment) const type sym[]
#define SCM_STATIC_OBJCODE(sym) \
SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode); \
SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = { \
{ SCM_PACK (OBJCODE_TAG), SCM_PACK (sym##__bytecode) }, \
{ SCM_BOOL_F, SCM_PACK (0) } \
}; \
static const SCM sym = SCM_PACK (sym##__cells); \
SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode)
#else
#define SCM_STATIC_OBJCODE(sym) \
static SCM sym; \
static scm_t_uint8 *sym##_bytecode; \
SCM_SNARF_INIT(sym##_bytecode = scm_gc_malloc_pointerless (sizeof(sym##_bytecode__unaligned), "partial continuation stub"); \
memcpy (sym##_bytecode, sym##_bytecode__unaligned, sizeof(sym##_bytecode__unaligned));) \
SCM_SNARF_INIT(sym = scm_double_cell (OBJCODE_TAG, \
(scm_t_bits)sym##_bytecode, \
SCM_UNPACK (SCM_BOOL_F), \
0);) \
static const scm_t_uint8 sym##_bytecode__unaligned[]
#endif
SCM_STATIC_OBJCODE (cont_objcode) = {
/* Like in continuations.c, but with partial-cont-call. */
OBJCODE_HEADER (8, 19),
/* leave args on the stack */
/* 0 */ scm_op_object_ref, 0, /* push scm_vm_cont object */
/* 2 */ scm_op_partial_cont_call, /* and go! */
/* 3 */ scm_op_nop,
/* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop, /* pad to 8 bytes */
/* 8 */
/* We could put some meta-info to say that this proc is a continuation. Not sure
how to do that, though. */
META_HEADER (19),
/* 0 */ scm_op_make_eol, /* bindings */
/* 1 */ scm_op_make_eol, /* sources */
/* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */
/* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */
/* 7 */ scm_op_make_int8_0, /* 0 optionals */
/* 8 */ scm_op_make_true, /* and a rest arg */
/* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */
/* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */
/* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */
/* 18 */ scm_op_return /* and return */
/* 19 */
};
static SCM
reify_partial_continuation (SCM vm,
SCM *saved_fp, SCM *saved_sp, scm_t_uint8 *saved_ip,
scm_i_jmp_buf *saved_registers,
scm_t_dynstack *dynstack,
scm_i_jmp_buf *current_registers)
{
SCM vm_cont, ret;
scm_t_uint32 flags;
flags = SCM_F_VM_CONT_PARTIAL;
/* If we are aborting to a prompt that has the same registers as those
of the abort, it means there are no intervening C frames on the
stack, and so the continuation can be relocated elsewhere on the
stack: it is rewindable. */
if (saved_registers && saved_registers == current_registers)
flags |= SCM_F_VM_CONT_REWINDABLE;
/* Since non-escape continuations should begin with a thunk application, the
first bit of the stack should be a frame, with the saved fp equal to the fp
that was current when the prompt was made. */
if ((SCM*)SCM_UNPACK (saved_sp[1]) != saved_fp)
abort ();
/* Capture from the top of the thunk application frame up to the end. Set an
MVRA only, as the post-abort code is in an MV context. */
vm_cont = scm_i_vm_capture_stack (saved_sp + 4,
SCM_VM_DATA (vm)->fp,
SCM_VM_DATA (vm)->sp,
NULL,
SCM_VM_DATA (vm)->ip,
dynstack,
flags);
ret = scm_make_program (cont_objcode,
scm_c_make_vector (1, vm_cont),
SCM_BOOL_F);
SCM_SET_CELL_WORD_0 (ret,
SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION);
return ret;
}
void
scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv,
scm_i_jmp_buf *current_registers)
{
SCM cont;
scm_t_dynstack *dynstack = &SCM_I_CURRENT_THREAD->dynstack;
scm_t_bits *prompt;
scm_t_dynstack_prompt_flags flags;
SCM *fp, *sp;
scm_t_uint8 *ip;
scm_i_jmp_buf *registers;
size_t i;
prompt = scm_dynstack_find_prompt (dynstack, tag,
&flags, &fp, &sp, &ip, ®isters);
if (!prompt)
scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag));
/* Only reify if the continuation referenced in the handler. */
if (flags & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY)
cont = SCM_BOOL_F;
else
{
scm_t_dynstack *captured;
captured = scm_dynstack_capture (dynstack, SCM_DYNSTACK_NEXT (prompt));
cont = reify_partial_continuation (vm, fp, sp, ip, registers, captured,
current_registers);
}
/* Unwind. */
scm_dynstack_unwind (dynstack, prompt);
/* Unwinding may have changed the current thread's VM, so use the
new one. */
vm = scm_the_vm ();
/* Restore VM regs */
SCM_VM_DATA (vm)->fp = fp;
SCM_VM_DATA (vm)->sp = sp;
SCM_VM_DATA (vm)->ip = ip;
/* Since we're jumping down, we should always have enough space. */
if (SCM_VM_DATA (vm)->sp + n + 1 >= SCM_VM_DATA (vm)->stack_limit)
abort ();
/* Push vals */
*(++(SCM_VM_DATA (vm)->sp)) = cont;
for (i = 0; i < n; i++)
*(++(SCM_VM_DATA (vm)->sp)) = argv[i];
*(++(SCM_VM_DATA (vm)->sp)) = scm_from_size_t (n+1); /* +1 for continuation */
/* Jump! */
SCM_I_LONGJMP (*registers, 1);
/* Shouldn't get here */
abort ();
}
SCM_DEFINE (scm_at_abort, "@abort", 2, 0, 0, (SCM tag, SCM args),
"Abort to the nearest prompt with tag @var{tag}.")
#define FUNC_NAME s_scm_at_abort
{
SCM *argv;
size_t i;
long n;
SCM_VALIDATE_LIST_COPYLEN (SCM_ARG2, args, n);
argv = alloca (sizeof (SCM)*n);
for (i = 0; i < n; i++, args = scm_cdr (args))
argv[i] = scm_car (args);
scm_c_abort (scm_the_vm (), tag, n, argv, NULL);
/* Oh, what, you're still here? The abort must have been reinstated. Actually,
that's quite impossible, given that we're already in C-land here, so...
abort! */
abort ();
}
#undef FUNC_NAME
void
scm_init_control (void)
{
#include "libguile/control.x"
}
/*
Local Variables:
c-file-style: "gnu"
End:
*/
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