/* 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 #endif #include #include "libguile/_scm.h" #include "libguile/control.h" #include "libguile/objcodes.h" #include "libguile/instructions.h" #include "libguile/vm.h" SCM scm_c_make_prompt (SCM k, SCM *fp, SCM *sp, scm_t_uint8 *abort_ip, scm_t_uint8 escape_only_p, scm_t_int64 vm_cookie, SCM winds) { scm_t_bits tag; struct scm_prompt_registers *regs; tag = scm_tc7_prompt; if (escape_only_p) tag |= (SCM_F_PROMPT_ESCAPE<<8); regs = scm_gc_malloc_pointerless (sizeof (*regs), "prompt registers"); regs->fp = fp; regs->sp = sp; regs->ip = abort_ip; regs->cookie = vm_cookie; return scm_double_cell (tag, SCM_UNPACK (k), (scm_t_bits)regs, SCM_UNPACK (winds)); } /* Only to be called if the SCM_PROMPT_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_object_ref, 1, /* push internal winds */ /* 4 */ scm_op_partial_cont_call, /* and go! */ /* 5 */ 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, 5, /* arity: from ip 0 to ip 7 */ /* 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 prompt, SCM extwinds, scm_t_int64 cookie) { SCM vm_cont, dynwinds, intwinds = SCM_EOL, ret; scm_t_uint32 flags; /* No need to reify if the continuation is never referenced in the handler. */ if (SCM_PROMPT_ESCAPE_P (prompt)) return SCM_BOOL_F; dynwinds = scm_i_dynwinds (); while (!scm_is_eq (dynwinds, extwinds)) { intwinds = scm_cons (scm_car (dynwinds), intwinds); dynwinds = scm_cdr (dynwinds); } flags = SCM_F_VM_CONT_PARTIAL; if (cookie >= 0 && SCM_PROMPT_REGISTERS (prompt)->cookie == cookie) 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 (SCM_PROMPT_REGISTERS (prompt)->sp[1]) != SCM_PROMPT_REGISTERS (prompt)->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 (SCM_PROMPT_REGISTERS (prompt)->sp + 4, SCM_VM_DATA (vm)->fp, SCM_VM_DATA (vm)->sp, NULL, SCM_VM_DATA (vm)->ip, flags); ret = scm_make_program (cont_objcode, scm_vector (scm_list_2 (vm_cont, intwinds)), 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_t_int64 cookie) { SCM cont, winds, prompt = SCM_BOOL_F; long delta; size_t i; /* Search the wind list for an appropriate prompt. "Waiter, please bring us the wind list." */ for (winds = scm_i_dynwinds (), delta = 0; scm_is_pair (winds); winds = SCM_CDR (winds), delta++) { SCM elt = SCM_CAR (winds); if (SCM_PROMPT_P (elt) && scm_is_eq (SCM_PROMPT_TAG (elt), tag)) { prompt = elt; break; } } /* If we didn't find anything, raise an error. */ if (scm_is_false (prompt)) scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag)); cont = reify_partial_continuation (vm, prompt, winds, cookie); /* Unwind once more, beyond the prompt. */ winds = SCM_CDR (winds), delta++; /* Unwind */ scm_dowinds (winds, delta); /* 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 = SCM_PROMPT_REGISTERS (prompt)->fp; SCM_VM_DATA (vm)->sp = SCM_PROMPT_REGISTERS (prompt)->sp; SCM_VM_DATA (vm)->ip = SCM_PROMPT_REGISTERS (prompt)->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 (SCM_PROMPT_REGISTERS (prompt)->regs, 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, -1); /* 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_i_prompt_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) { scm_puts ("#', port); } void scm_init_control (void) { #include "libguile/control.x" } /* Local Variables: c-file-style: "gnu" End: */