| | 1 | /* Copyright (C) 1995,1996, 1997, 2000, 2001 Free Software Foundation, Inc. |
| | 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 |
| | 15 | * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, |
| | 16 | * Boston, MA 02111-1307 USA |
| | 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. |
| | 40 | * If you do not wish that, delete this exception notice. */ |
| | 41 | |
| | 42 | |
| | 43 | \f |
| | 44 | |
| | 45 | #include "libguile/_scm.h" |
| | 46 | #include "libguile/ports.h" |
| | 47 | #include "libguile/smob.h" |
| | 48 | |
| | 49 | #include "libguile/validate.h" |
| | 50 | #include "libguile/arbiters.h" |
| | 51 | |
| | 52 | \f |
| | 53 | /* {Arbiters} |
| | 54 | * |
| | 55 | * These procedures implement synchronization primitives. Processors |
| | 56 | * with an atomic test-and-set instruction can use it here (and not |
| | 57 | * SCM_DEFER_INTS). |
| | 58 | */ |
| | 59 | |
| | 60 | static scm_t_bits scm_tc16_arbiter; |
| | 61 | |
| | 62 | |
| | 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)); |
| | 66 | |
| | 67 | static int |
| | 68 | arbiter_print (SCM exp, SCM port, scm_print_state *pstate) |
| | 69 | { |
| | 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); |
| | 74 | scm_putc ('>', port); |
| | 75 | return !0; |
| | 76 | } |
| | 77 | |
| | 78 | SCM_DEFINE (scm_make_arbiter, "make-arbiter", 1, 0, 0, |
| | 79 | (SCM name), |
| | 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 |
| | 84 | { |
| | 85 | SCM_RETURN_NEWSMOB (scm_tc16_arbiter, SCM_UNPACK (name)); |
| | 86 | } |
| | 87 | #undef FUNC_NAME |
| | 88 | |
| | 89 | SCM_DEFINE (scm_try_arbiter, "try-arbiter", 1, 0, 0, |
| | 90 | (SCM arb), |
| | 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 |
| | 94 | { |
| | 95 | SCM_VALIDATE_SMOB (1, arb, arbiter); |
| | 96 | SCM_DEFER_INTS; |
| | 97 | if (SCM_ARB_LOCKED(arb)) |
| | 98 | arb = SCM_BOOL_F; |
| | 99 | else |
| | 100 | { |
| | 101 | SCM_LOCK_ARB(arb); |
| | 102 | arb = SCM_BOOL_T; |
| | 103 | } |
| | 104 | SCM_ALLOW_INTS; |
| | 105 | return arb; |
| | 106 | } |
| | 107 | #undef FUNC_NAME |
| | 108 | |
| | 109 | |
| | 110 | SCM_DEFINE (scm_release_arbiter, "release-arbiter", 1, 0, 0, |
| | 111 | (SCM arb), |
| | 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 |
| | 115 | { |
| | 116 | SCM_VALIDATE_SMOB (1, arb, arbiter); |
| | 117 | if (!SCM_ARB_LOCKED(arb)) |
| | 118 | return SCM_BOOL_F; |
| | 119 | SCM_UNLOCK_ARB (arb); |
| | 120 | return SCM_BOOL_T; |
| | 121 | } |
| | 122 | #undef FUNC_NAME |
| | 123 | |
| | 124 | |
| | 125 | |
| | 126 | void |
| | 127 | scm_init_arbiters () |
| | 128 | { |
| | 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" |
| | 133 | } |
| | 134 | |
| | 135 | /* |
| | 136 | Local Variables: |
| | 137 | c-file-style: "gnu" |
| | 138 | End: |
| | 139 | */ |
HCoop / bpt / guile.git / blame_incremental