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129 lines
4.3 KiB
129 lines
4.3 KiB
/**************************************************************************** |
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* nuttx/graphics/nxconsole/nxcon_sem.c |
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* |
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* Copyright (C) 2012 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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****************************************************************************/ |
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/**************************************************************************** |
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* Included Files |
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****************************************************************************/ |
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#include <nuttx/config.h> |
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#include <unistd.h> |
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#include <semaphore.h> |
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#include <assert.h> |
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#include <errno.h> |
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#include "nxcon_internal.h" |
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#ifdef CONFIG_DEBUG |
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/**************************************************************************** |
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* Pre-processor Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Function Prototypes |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Data |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Name: nxcon_semwait and nxcon_sempost |
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* |
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* Description: |
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* If debug is on, then lower level code may attempt console output while |
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* we are doing console output! In this case, we will toss the nested |
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* output to avoid deadlocks and infinite loops. |
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* |
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* Input Parameters: |
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* priv - Driver data structure |
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* |
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* Returned Value: |
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* |
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* |
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****************************************************************************/ |
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int nxcon_semwait(FAR struct nxcon_state_s *priv) |
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{ |
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pid_t me; |
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int ret; |
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/* Does I already hold the semaphore */ |
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me = getpid(); |
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if (priv->holder != me) |
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{ |
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/* No.. then wait until the thread that does hold it is finished with it */ |
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ret = sem_wait(&priv->exclsem); |
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if (ret == OK) |
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{ |
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/* No I hold the semaphore */ |
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priv->holder = me; |
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} |
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return ret; |
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} |
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/* Abort, abort, abort! I have been re-entered */ |
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set_errno(EBUSY); |
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return ERROR; |
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} |
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int nxcon_sempost(FAR struct nxcon_state_s *priv) |
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{ |
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pid_t me = getpid(); |
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/* Make sure that I really hold the semaphore */ |
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ASSERT(priv->holder == me); |
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/* Then let go of it */ |
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priv->holder = NO_HOLDER; |
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return sem_post(&priv->exclsem); |
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} |
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#endif /* CONFIG_DEBUG */
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