/* ==== cond.c ============================================================ * Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Chris Provenzano. * 4. The name of Chris Provenzano may not be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL CHRIS PROVENZANO BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * Description : Condition cariable functions. * * 1.00 93/10/28 proven * -Started coding this file. */ #ifndef lint static const char rcsid[] = "$Id: cond.c,v 1.1 1995/10/18 08:43:04 deraadt Exp $ $provenid: cond.c,v 1.16 1994/02/07 02:18:35 proven Exp $"; #endif #include #include /* ========================================================================== * pthread_cond_init() * * In this implementation I don't need to allocate memory. * ENOMEM, EAGAIN should never be returned. Arch that have * weird constraints may need special coding. */ int pthread_cond_init(pthread_cond_t *cond, pthread_condattr_t *cond_attr) { /* Only check if attr specifies some mutex type other than fast */ if ((cond_attr) && (cond_attr->c_type != COND_TYPE_FAST)) { if (cond_attr->c_type >= COND_TYPE_MAX) { return(EINVAL); } if (cond->c_flags & COND_FLAGS_INITED) { return(EBUSY); } cond->c_type = cond_attr->c_type; } else { cond->c_type = COND_TYPE_FAST; } /* Set all other paramaters */ pthread_queue_init(&cond->c_queue); cond->c_flags |= COND_FLAGS_INITED; cond->c_lock = SEMAPHORE_CLEAR; return(OK); } /* ========================================================================== * pthread_cond_destroy() */ int pthread_cond_destroy(pthread_cond_t *cond) { /* Only check if cond is of type other than fast */ switch(cond->c_type) { case COND_TYPE_FAST: break; case COND_TYPE_STATIC_FAST: default: return(EINVAL); break; } /* Cleanup cond, others might want to use it. */ pthread_queue_init(&cond->c_queue); cond->c_flags |= COND_FLAGS_INITED; cond->c_lock = SEMAPHORE_CLEAR; cond->c_flags = 0; return(OK); } /* ========================================================================== * pthread_cond_wait() */ int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex) { semaphore *lock, *plock; int rval; lock = &(cond->c_lock); while (SEMAPHORE_TEST_AND_SET(lock)) { pthread_yield(); } switch (cond->c_type) { /* * Fast condition variables do not check for any error conditions. */ case COND_TYPE_FAST: case COND_TYPE_STATIC_FAST: plock = &(pthread_run->lock); while (SEMAPHORE_TEST_AND_SET(plock)) { pthread_yield(); } pthread_queue_enq(&cond->c_queue, pthread_run); pthread_mutex_unlock(mutex); SEMAPHORE_RESET(lock); /* Reschedule will unlock pthread_run */ reschedule(PS_COND_WAIT); return(pthread_mutex_lock(mutex)); break; default: rval = EINVAL; break; } SEMAPHORE_RESET(lock); return(rval); } /* ========================================================================== * pthread_cond_signal() */ int pthread_cond_signal(pthread_cond_t *cond) { struct pthread *pthread; semaphore *lock, *plock; int rval; lock = &(cond->c_lock); while (SEMAPHORE_TEST_AND_SET(lock)) { pthread_yield(); } switch (cond->c_type) { case COND_TYPE_FAST: case COND_TYPE_STATIC_FAST: if (pthread = pthread_queue_get(&cond->c_queue)) { plock = &(pthread->lock); while (SEMAPHORE_TEST_AND_SET(plock)) { pthread_yield(); } pthread_queue_deq(&cond->c_queue); pthread->state = PS_RUNNING; SEMAPHORE_RESET(plock); } rval = OK; break; default: rval = EINVAL; break; } SEMAPHORE_RESET(lock); return(rval); } /* ========================================================================== * pthread_cond_broadcast() * * Not much different then the above routine. */ int pthread_cond_broadcast(pthread_cond_t *cond) { struct pthread *pthread; semaphore *lock, *plock; int rval; lock = &(cond->c_lock); while (SEMAPHORE_TEST_AND_SET(lock)) { pthread_yield(); } switch (cond->c_type) { case COND_TYPE_FAST: case COND_TYPE_STATIC_FAST: while (pthread = pthread_queue_get(&cond->c_queue)) { plock = &(pthread->lock); while (SEMAPHORE_TEST_AND_SET(plock)) { pthread_yield(); } pthread_queue_deq(&cond->c_queue); pthread->state = PS_RUNNING; SEMAPHORE_RESET(plock); } rval = OK; break; default: rval = EINVAL; break; } SEMAPHORE_RESET(lock); return(rval); }