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Diffstat (limited to 'nuttx/graphics/nxconsole/nxcon_sem.c')
-rw-r--r-- | nuttx/graphics/nxconsole/nxcon_sem.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/nuttx/graphics/nxconsole/nxcon_sem.c b/nuttx/graphics/nxconsole/nxcon_sem.c new file mode 100644 index 000000000..4cf960971 --- /dev/null +++ b/nuttx/graphics/nxconsole/nxcon_sem.c @@ -0,0 +1,129 @@ +/**************************************************************************** + * nuttx/graphics/nxconsole/nxcon_sem.c + * + * Copyright (C) 2012 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * 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 NuttX 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 <nuttx/config.h> + +#include <unistd.h> +#include <semaphore.h> +#include <assert.h> +#include <errno.h> + +#include "nxcon_internal.h" + +#ifdef CONFIG_DEBUG + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: nxcon_semwait and nxcon_sempost + * + * Description: + * If debug is on, then lower level code may attempt console output while + * we are doing console output! In this case, we will toss the nested + * output to avoid deadlocks and infinite loops. + * + * Input Parameters: + * priv - Driver data structure + * + * Returned Value: + * + * + ****************************************************************************/ + +int nxcon_semwait(FAR struct nxcon_state_s *priv) +{ + pid_t me; + int ret; + + /* Does I already hold the semaphore */ + + me = getpid(); + if (priv->holder != me) + { + /* No.. then wait until the thread that does hold it is finished with it */ + + ret = sem_wait(&priv->exclsem); + if (ret == OK) + { + /* No I hold the semaphore */ + + priv->holder = me; + } + return ret; + } + + /* Abort, abort, abort! I have been re-entered */ + + set_errno(EBUSY); + return ERROR; +} + +int nxcon_sempost(FAR struct nxcon_state_s *priv) +{ + pid_t me = getpid(); + + /* Make sure that I really hold the semaphore */ + + ASSERT(priv->holder == me); + + /* Then let go of it */ + + priv->holder = NO_HOLDER; + return sem_post(&priv->exclsem); +} + +#endif /* CONFIG_DEBUG */ |