qsem.c (2266B)
1 /* $Id: //depot/blt/lib/libc/qsem.c#1 $ 2 ** 3 ** Copyright 1999 Sidney Cammeresi. 4 ** All rights reserved. 5 ** 6 ** Redistribution and use in source and binary forms, with or without 7 ** modification, are permitted provided that the following conditions 8 ** are met: 9 ** 10 ** 1. Redistributions of source code must retain the above copyright notice, 11 ** this list of conditions and the following disclaimer. 12 ** 13 ** 2. Redistributions in binary form must reproduce the above copyright 14 ** notice, this list of conditions and the following disclaimer in the 15 ** documentation and/or other materials provided with the distribution. 16 ** 17 ** 3. The name of the author may not be used to endorse or promote products 18 ** derived from this software without specific prior written permission. 19 ** 20 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS' AND ANY EXPRESS OR IMPLIED 21 ** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 22 ** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN 23 ** NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 25 ** TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 26 ** PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 27 ** LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 28 ** NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 29 ** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <stdlib.h> 33 #include <blt/syscall.h> 34 #include <blt/qsem.h> 35 36 qsem_t *qsem_create (int count) 37 { 38 qsem_t *s; 39 40 s = (qsem_t *) malloc (sizeof (qsem_t)); 41 #ifdef I386 42 s->mutex = sem_create (count, "qsem_mutex"); 43 s->count = 0; 44 #else 45 s->mutex = sem_create (0, "qsem_mutex"); 46 s->count = count; 47 #endif 48 return s; 49 } 50 51 void qsem_destroy (qsem_t *s) 52 { 53 sem_destroy (s->mutex); 54 free (s); 55 } 56 57 void qsem_acquire (qsem_t *s) 58 { 59 #ifdef I386 60 /* no atomic_add() in i386 */ 61 sem_acquire(s->mutex); 62 #else 63 if (atomic_add (&s->count, -1) <= 0) 64 sem_acquire (s->mutex); 65 #endif 66 } 67 68 void qsem_release (qsem_t *s) 69 { 70 #ifdef I386 71 /* no atomic_add() in i386 */ 72 sem_release(s->mutex); 73 #else 74 if (atomic_add (&s->count, 1) < 0) 75 sem_release (s->mutex); 76 #endif 77 } 78