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Diffstat (limited to 'nuttx/sched/pthread_condsignal.c')
-rw-r--r-- | nuttx/sched/pthread_condsignal.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/nuttx/sched/pthread_condsignal.c b/nuttx/sched/pthread_condsignal.c new file mode 100644 index 000000000..f9ee3781d --- /dev/null +++ b/nuttx/sched/pthread_condsignal.c @@ -0,0 +1,126 @@ +/************************************************************ + * pthread_condsignal.c + * + * Copyright (C) 2007 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * 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. Neither the name Gregory Nutt nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "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 THE + * COPYRIGHT OWNER OR CONTRIBUTORS 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. + * + ************************************************************/ + +/************************************************************ + * Included Files + ************************************************************/ + +#include <sys/types.h> +#include <pthread.h> +#include <errno.h> +#include <debug.h> +#include "pthread_internal.h" + +/************************************************************ + * Definitions + ************************************************************/ + +/************************************************************ + * Private Type Declarations + ************************************************************/ + +/************************************************************ + * Global Variables + ************************************************************/ + +/************************************************************ + * Private Variables + ************************************************************/ + +/************************************************************ + * Private Functions + ************************************************************/ + +/************************************************************ + * Public Functions + ************************************************************/ + +/************************************************************ + * Function: pthread_cond_signal + * + * Description: + * A thread can signal on a condition variable. + * + * Parameters: + * None + * + * Return Value: + * None + * + * Assumptions: + * + ************************************************************/ + +int pthread_cond_signal(pthread_cond_t *cond) +{ + int ret = OK; + int sval; + + dbg("%s: cond=0x%p\n", __FUNCTION__, cond); + + if (!cond) + { + ret = EINVAL; + } + else + { + /* Get the current value of the semaphore */ + + if (sem_getvalue((sem_t*)&cond->sem, &sval) != OK) + { + ret = EINVAL; + } + + /* If the value is less than zero (meaning that one or more + * thread is waiting), then post the condition semaphore. + * Only the highest priority waiting thread will get to execute + */ + + else + { + dbg("%s: sval=%d\n", __FUNCTION__, sval); + if (sval < 0) + { + dbg("%s: Signalling...\n", __FUNCTION__); + ret = pthread_givesemaphore((sem_t*)&cond->sem); + } + } + } + + dbg("%s: Returning %d\n", __FUNCTION__, ret); + return ret; +} + + |