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0bc908e7 | 1 | /* Copyright (C) 1995,1996, 1997, 2000 Free Software Foundation, Inc. |
0f2d19dd JB |
2 | * |
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) | |
6 | * any later version. | |
7 | * | |
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. | |
12 | * | |
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 | |
82892bed JB |
15 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
16 | * Boston, MA 02111-1307 USA | |
0f2d19dd JB |
17 | * |
18 | * As a special exception, the Free Software Foundation gives permission | |
19 | * for additional uses of the text contained in its release of GUILE. | |
20 | * | |
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. | |
26 | * | |
27 | * This exception does not however invalidate any other reasons why | |
28 | * the executable file might be covered by the GNU General Public License. | |
29 | * | |
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. | |
37 | * | |
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. | |
82892bed | 40 | * If you do not wish that, delete this exception notice. */ |
1bbd0b84 GB |
41 | |
42 | /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999, | |
43 | gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */ | |
44 | ||
0f2d19dd JB |
45 | \f |
46 | ||
a0599745 MD |
47 | #include "libguile/_scm.h" |
48 | #include "libguile/ports.h" | |
49 | #include "libguile/smob.h" | |
20e6290e | 50 | |
a0599745 MD |
51 | #include "libguile/validate.h" |
52 | #include "libguile/arbiters.h" | |
0f2d19dd JB |
53 | |
54 | \f | |
55 | /* {Arbiters} | |
56 | * | |
57 | * These procedures implement synchronization primitives. Processors | |
58 | * with an atomic test-and-set instruction can use it here (and not | |
59 | * SCM_DEFER_INTS). | |
60 | */ | |
61 | ||
92c2555f | 62 | static scm_t_bits scm_tc16_arbiter; |
0f2d19dd | 63 | |
1cc91f1b | 64 | |
843524cc DH |
65 | #define SCM_ARB_LOCKED(arb) ((SCM_CELL_WORD_0 (arb)) & (1L << 16)) |
66 | #define SCM_LOCK_ARB(arb) (SCM_SET_CELL_WORD_0 ((arb), scm_tc16_arbiter | (1L << 16))); | |
67 | #define SCM_UNLOCK_ARB(arb) (SCM_SET_CELL_WORD_0 ((arb), scm_tc16_arbiter)); | |
c209c88e | 68 | |
0f2d19dd | 69 | static int |
e841c3e0 | 70 | arbiter_print (SCM exp, SCM port, scm_print_state *pstate) |
0f2d19dd | 71 | { |
b7f3516f | 72 | scm_puts ("#<arbiter ", port); |
c209c88e | 73 | if (SCM_ARB_LOCKED (exp)) |
b7f3516f | 74 | scm_puts ("locked ", port); |
cb87e06a | 75 | scm_iprin1 (SCM_PACK (SCM_SMOB_DATA (exp)), port, pstate); |
b7f3516f | 76 | scm_putc ('>', port); |
0f2d19dd JB |
77 | return !0; |
78 | } | |
79 | ||
3b3b36dd | 80 | SCM_DEFINE (scm_make_arbiter, "make-arbiter", 1, 0, 0, |
cb87e06a MG |
81 | (SCM name), |
82 | "Return an object of type arbiter and name @var{name}. Its\n" | |
83 | "state is initially unlocked. Arbiters are a way to achieve\n" | |
84 | "process synchronization.") | |
1bbd0b84 | 85 | #define FUNC_NAME s_scm_make_arbiter |
0f2d19dd | 86 | { |
843524cc | 87 | SCM_RETURN_NEWSMOB (scm_tc16_arbiter, SCM_UNPACK (name)); |
0f2d19dd | 88 | } |
1bbd0b84 | 89 | #undef FUNC_NAME |
0f2d19dd | 90 | |
3b3b36dd | 91 | SCM_DEFINE (scm_try_arbiter, "try-arbiter", 1, 0, 0, |
cb87e06a MG |
92 | (SCM arb), |
93 | "Return @code{#t} and lock the arbiter @var{arb} if the arbiter\n" | |
94 | "was unlocked. Otherwise, return @code{#f}.") | |
1bbd0b84 | 95 | #define FUNC_NAME s_scm_try_arbiter |
0f2d19dd | 96 | { |
cb87e06a | 97 | SCM_VALIDATE_SMOB (1, arb, arbiter); |
0f2d19dd | 98 | SCM_DEFER_INTS; |
c209c88e | 99 | if (SCM_ARB_LOCKED(arb)) |
0f2d19dd JB |
100 | arb = SCM_BOOL_F; |
101 | else | |
102 | { | |
c209c88e | 103 | SCM_LOCK_ARB(arb); |
0f2d19dd JB |
104 | arb = SCM_BOOL_T; |
105 | } | |
106 | SCM_ALLOW_INTS; | |
107 | return arb; | |
108 | } | |
1bbd0b84 | 109 | #undef FUNC_NAME |
0f2d19dd JB |
110 | |
111 | ||
3b3b36dd | 112 | SCM_DEFINE (scm_release_arbiter, "release-arbiter", 1, 0, 0, |
cb87e06a MG |
113 | (SCM arb), |
114 | "Return @code{#t} and unlock the arbiter @var{arb} if the\n" | |
115 | "arbiter was locked. Otherwise, return @code{#f}.") | |
1bbd0b84 | 116 | #define FUNC_NAME s_scm_release_arbiter |
0f2d19dd | 117 | { |
cb87e06a MG |
118 | SCM_VALIDATE_SMOB (1, arb, arbiter); |
119 | if (!SCM_ARB_LOCKED(arb)) | |
0f2d19dd | 120 | return SCM_BOOL_F; |
c209c88e | 121 | SCM_UNLOCK_ARB (arb); |
0f2d19dd JB |
122 | return SCM_BOOL_T; |
123 | } | |
1bbd0b84 | 124 | #undef FUNC_NAME |
0f2d19dd JB |
125 | |
126 | ||
1cc91f1b | 127 | |
0f2d19dd JB |
128 | void |
129 | scm_init_arbiters () | |
0f2d19dd | 130 | { |
e841c3e0 KN |
131 | scm_tc16_arbiter = scm_make_smob_type ("arbiter", 0); |
132 | scm_set_smob_mark (scm_tc16_arbiter, scm_markcdr); | |
133 | scm_set_smob_print (scm_tc16_arbiter, arbiter_print); | |
8dc9439f | 134 | #ifndef SCM_MAGIC_SNARFER |
a0599745 | 135 | #include "libguile/arbiters.x" |
8dc9439f | 136 | #endif |
0f2d19dd | 137 | } |
89e00824 ML |
138 | |
139 | /* | |
140 | Local Variables: | |
141 | c-file-style: "gnu" | |
142 | End: | |
143 | */ |