1 /* Copyright (C) 1995,1996, 1997, 2000, 2001 Free Software Foundation, Inc.
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2, or (at your option)
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
13 * You should have received a copy of the GNU General Public License
14 * along with this software; see the file COPYING. If not, write to
15 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
16 * Boston, MA 02111-1307 USA
18 * As a special exception, the Free Software Foundation gives permission
19 * for additional uses of the text contained in its release of GUILE.
21 * The exception is that, if you link the GUILE library with other files
22 * to produce an executable, this does not by itself cause the
23 * resulting executable to be covered by the GNU General Public License.
24 * Your use of that executable is in no way restricted on account of
25 * linking the GUILE library code into it.
27 * This exception does not however invalidate any other reasons why
28 * the executable file might be covered by the GNU General Public License.
30 * This exception applies only to the code released by the
31 * Free Software Foundation under the name GUILE. If you copy
32 * code from other Free Software Foundation releases into a copy of
33 * GUILE, as the General Public License permits, the exception does
34 * not apply to the code that you add in this way. To avoid misleading
35 * anyone as to the status of such modified files, you must delete
36 * this exception notice from them.
38 * If you write modifications of your own for GUILE, it is your choice
39 * whether to permit this exception to apply to your modifications.
40 * If you do not wish that, delete this exception notice. */
45 #include "libguile/_scm.h"
46 #include "libguile/ports.h"
47 #include "libguile/smob.h"
49 #include "libguile/validate.h"
50 #include "libguile/arbiters.h"
55 * These procedures implement synchronization primitives. Processors
56 * with an atomic test-and-set instruction can use it here (and not
60 static scm_t_bits scm_tc16_arbiter
;
63 #define SCM_ARB_LOCKED(arb) ((SCM_CELL_WORD_0 (arb)) & (1L << 16))
64 #define SCM_LOCK_ARB(arb) (SCM_SET_CELL_WORD_0 ((arb), scm_tc16_arbiter | (1L << 16)));
65 #define SCM_UNLOCK_ARB(arb) (SCM_SET_CELL_WORD_0 ((arb), scm_tc16_arbiter));
68 arbiter_print (SCM exp
, SCM port
, scm_print_state
*pstate
)
70 scm_puts ("#<arbiter ", port
);
71 if (SCM_ARB_LOCKED (exp
))
72 scm_puts ("locked ", port
);
73 scm_iprin1 (SCM_PACK (SCM_SMOB_DATA (exp
)), port
, pstate
);
78 SCM_DEFINE (scm_make_arbiter
, "make-arbiter", 1, 0, 0,
80 "Return an object of type arbiter and name @var{name}. Its\n"
81 "state is initially unlocked. Arbiters are a way to achieve\n"
82 "process synchronization.")
83 #define FUNC_NAME s_scm_make_arbiter
85 SCM_RETURN_NEWSMOB (scm_tc16_arbiter
, SCM_UNPACK (name
));
89 SCM_DEFINE (scm_try_arbiter
, "try-arbiter", 1, 0, 0,
91 "Return @code{#t} and lock the arbiter @var{arb} if the arbiter\n"
92 "was unlocked. Otherwise, return @code{#f}.")
93 #define FUNC_NAME s_scm_try_arbiter
95 SCM_VALIDATE_SMOB (1, arb
, arbiter
);
97 if (SCM_ARB_LOCKED(arb
))
110 SCM_DEFINE (scm_release_arbiter
, "release-arbiter", 1, 0, 0,
112 "Return @code{#t} and unlock the arbiter @var{arb} if the\n"
113 "arbiter was locked. Otherwise, return @code{#f}.")
114 #define FUNC_NAME s_scm_release_arbiter
116 SCM_VALIDATE_SMOB (1, arb
, arbiter
);
117 if (!SCM_ARB_LOCKED(arb
))
119 SCM_UNLOCK_ARB (arb
);
129 scm_tc16_arbiter
= scm_make_smob_type ("arbiter", 0);
130 scm_set_smob_mark (scm_tc16_arbiter
, scm_markcdr
);
131 scm_set_smob_print (scm_tc16_arbiter
, arbiter_print
);
132 #include "libguile/arbiters.x"