1 /* 2 * ------------------------------------------------------------- 3 * 4 * Module: sem_post_multiple.c 5 * 6 * Purpose: 7 * Semaphores aren't actually part of the PThreads standard. 8 * They are defined by the POSIX Standard: 9 * 10 * POSIX 1003.1b-1993 (POSIX.1b) 11 * 12 * ------------------------------------------------------------- 13 * 14 * -------------------------------------------------------------------------- 15 * 16 * Pthreads-win32 - POSIX Threads Library for Win32 17 * Copyright(C) 1998 John E. Bossom 18 * Copyright(C) 1999,2005 Pthreads-win32 contributors 19 * 20 * Contact Email: rpj (at) callisto.canberra.edu.au 21 * 22 * The current list of contributors is contained 23 * in the file CONTRIBUTORS included with the source 24 * code distribution. The list can also be seen at the 25 * following World Wide Web location: 26 * http://sources.redhat.com/pthreads-win32/contributors.html 27 * 28 * This library is free software; you can redistribute it and/or 29 * modify it under the terms of the GNU Lesser General Public 30 * License as published by the Free Software Foundation; either 31 * version 2 of the License, or (at your option) any later version. 32 * 33 * This library is distributed in the hope that it will be useful, 34 * but WITHOUT ANY WARRANTY; without even the implied warranty of 35 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 36 * Lesser General Public License for more details. 37 * 38 * You should have received a copy of the GNU Lesser General Public 39 * License along with this library in the file COPYING.LIB; 40 * if not, write to the Free Software Foundation, Inc., 41 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 42 */ 43 44 #include "pthread.h" 45 #include "semaphore.h" 46 #include "implement.h" 47 48 49 int 50 sem_post_multiple (sem_t * sem, int count) 51 /* 52 * ------------------------------------------------------ 53 * DOCPUBLIC 54 * This function posts multiple wakeups to a semaphore. 55 * 56 * PARAMETERS 57 * sem 58 * pointer to an instance of sem_t 59 * 60 * count 61 * counter, must be greater than zero. 62 * 63 * DESCRIPTION 64 * This function posts multiple wakeups to a semaphore. If there 65 * are waiting threads (or processes), n <= count are awakened; 66 * the semaphore value is incremented by count - n. 67 * 68 * RESULTS 69 * 0 successfully posted semaphore, 70 * -1 failed, error in errno 71 * ERRNO 72 * EINVAL 'sem' is not a valid semaphore 73 * or count is less than or equal to zero. 74 * ERANGE semaphore count is too big 75 * 76 * ------------------------------------------------------ 77 */ 78 { 79 int result = 0; 80 long waiters; 81 sem_t s = *sem; 82 83 if (s == NULL || count <= 0) 84 { 85 result = EINVAL; 86 } 87 else if ((result = pthread_mutex_lock (&s->lock)) == 0) 88 { 89 /* See sem_destroy.c 90 */ 91 if (*sem == NULL) 92 { 93 (void) pthread_mutex_unlock (&s->lock); 94 result = EINVAL; 95 return -1; 96 } 97 98 if (s->value <= (SEM_VALUE_MAX - count)) 99 { 100 waiters = -s->value; 101 s->value += count; 102 if (waiters > 0) 103 { 104 #if defined(NEED_SEM) 105 if (SetEvent(s->sem)) 106 { 107 waiters--; 108 s->leftToUnblock += count - 1; 109 if (s->leftToUnblock > waiters) 110 { 111 s->leftToUnblock = waiters; 112 } 113 } 114 #else 115 if (ReleaseSemaphore (s->sem, (waiters<=count)?waiters:count, 0)) 116 { 117 /* No action */ 118 } 119 #endif 120 else 121 { 122 s->value -= count; 123 result = EINVAL; 124 } 125 } 126 } 127 else 128 { 129 result = ERANGE; 130 } 131 (void) pthread_mutex_unlock (&s->lock); 132 } 133 134 if (result != 0) 135 { 136 errno = result; 137 return -1; 138 } 139 140 return 0; 141 142 } /* sem_post_multiple */ 143
