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- /* Copyright (C) 2010, 2011, 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
- */
- #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_abort_to_prompt_star, "abort-to-prompt*", 2, 0, 0,
- (SCM tag, SCM args),
- "Abort to the nearest prompt with tag @var{tag}, yielding the\n"
- "values in the list, @var{args}.")
- #define FUNC_NAME s_scm_abort_to_prompt_star
- {
- 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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