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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 | ||
47 | #include <stdio.h> | |
a0599745 MD |
48 | #include "libguile/_scm.h" |
49 | #include "libguile/ports.h" | |
50 | #include "libguile/smob.h" | |
20e6290e | 51 | |
a0599745 MD |
52 | #include "libguile/validate.h" |
53 | #include "libguile/arbiters.h" | |
0f2d19dd JB |
54 | |
55 | \f | |
56 | /* {Arbiters} | |
57 | * | |
58 | * These procedures implement synchronization primitives. Processors | |
59 | * with an atomic test-and-set instruction can use it here (and not | |
60 | * SCM_DEFER_INTS). | |
61 | */ | |
62 | ||
e841c3e0 | 63 | static scm_bits_t scm_tc16_arbiter; |
0f2d19dd | 64 | |
1cc91f1b | 65 | |
843524cc DH |
66 | #define SCM_ARB_LOCKED(arb) ((SCM_CELL_WORD_0 (arb)) & (1L << 16)) |
67 | #define SCM_LOCK_ARB(arb) (SCM_SET_CELL_WORD_0 ((arb), scm_tc16_arbiter | (1L << 16))); | |
68 | #define SCM_UNLOCK_ARB(arb) (SCM_SET_CELL_WORD_0 ((arb), scm_tc16_arbiter)); | |
c209c88e | 69 | |
0f2d19dd | 70 | static int |
e841c3e0 | 71 | arbiter_print (SCM exp, SCM port, scm_print_state *pstate) |
0f2d19dd | 72 | { |
b7f3516f | 73 | scm_puts ("#<arbiter ", port); |
c209c88e | 74 | if (SCM_ARB_LOCKED (exp)) |
b7f3516f | 75 | scm_puts ("locked ", port); |
9882ea19 | 76 | scm_iprin1 (SCM_CDR (exp), port, pstate); |
b7f3516f | 77 | scm_putc ('>', port); |
0f2d19dd JB |
78 | return !0; |
79 | } | |
80 | ||
3b3b36dd | 81 | SCM_DEFINE (scm_make_arbiter, "make-arbiter", 1, 0, 0, |
1bbd0b84 | 82 | (SCM name), |
b450f070 GB |
83 | "Returns an object of type arbiter and name name. Its state is initially unlocked.\n" |
84 | "Arbiters are a way to achieve 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, |
1bbd0b84 | 92 | (SCM arb), |
b450f070 | 93 | "Returns #t and locks arbiter if arbiter was unlocked. Otherwise, returns #f.") |
1bbd0b84 | 94 | #define FUNC_NAME s_scm_try_arbiter |
0f2d19dd | 95 | { |
3b3b36dd | 96 | SCM_VALIDATE_SMOB (1,arb,arbiter); |
0f2d19dd | 97 | SCM_DEFER_INTS; |
c209c88e | 98 | if (SCM_ARB_LOCKED(arb)) |
0f2d19dd JB |
99 | arb = SCM_BOOL_F; |
100 | else | |
101 | { | |
c209c88e | 102 | SCM_LOCK_ARB(arb); |
0f2d19dd JB |
103 | arb = SCM_BOOL_T; |
104 | } | |
105 | SCM_ALLOW_INTS; | |
106 | return arb; | |
107 | } | |
1bbd0b84 | 108 | #undef FUNC_NAME |
0f2d19dd JB |
109 | |
110 | ||
3b3b36dd | 111 | SCM_DEFINE (scm_release_arbiter, "release-arbiter", 1, 0, 0, |
1bbd0b84 | 112 | (SCM arb), |
b450f070 | 113 | "Returns #t and unlocks arbiter if arbiter was locked. Otherwise, returns #f.") |
1bbd0b84 | 114 | #define FUNC_NAME s_scm_release_arbiter |
0f2d19dd | 115 | { |
3b3b36dd | 116 | SCM_VALIDATE_SMOB (1,arb,arbiter); |
c209c88e | 117 | if (! SCM_ARB_LOCKED(arb)) |
0f2d19dd | 118 | return SCM_BOOL_F; |
c209c88e | 119 | SCM_UNLOCK_ARB (arb); |
0f2d19dd JB |
120 | return SCM_BOOL_T; |
121 | } | |
1bbd0b84 | 122 | #undef FUNC_NAME |
0f2d19dd JB |
123 | |
124 | ||
1cc91f1b | 125 | |
0f2d19dd JB |
126 | void |
127 | scm_init_arbiters () | |
0f2d19dd | 128 | { |
e841c3e0 KN |
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); | |
8dc9439f | 132 | #ifndef SCM_MAGIC_SNARFER |
a0599745 | 133 | #include "libguile/arbiters.x" |
8dc9439f | 134 | #endif |
0f2d19dd | 135 | } |
89e00824 ML |
136 | |
137 | /* | |
138 | Local Variables: | |
139 | c-file-style: "gnu" | |
140 | End: | |
141 | */ |