2008-07-26 13:12:11 +00:00
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/****************************************************************************
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* drivers/pipe-common.c
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*
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* Copyright (C) 2008 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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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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* Compilation Switches
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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 <sys/types.h>
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#include <sys/stat.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sched.h>
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#include <semaphore.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <assert.h>
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#include <nuttx/fs.h>
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#include "pipe-common.h"
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2008-07-26 14:02:46 +00:00
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#if CONFIG_DEV_PIPE_SIZE > 0
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2008-07-26 13:12:11 +00:00
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/****************************************************************************
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* Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static void pipecommon_semtake(sem_t *sem);
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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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* Name: pipecommon_semtake
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****************************************************************************/
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static void pipecommon_semtake(sem_t *sem)
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{
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while (sem_wait(sem) != 0)
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{
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/* The only case that an error should occur here is if the wait was
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* awakened by a signal.
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*/
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ASSERT(errno == EINTR);
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}
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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: pipecommon_allocdev
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****************************************************************************/
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FAR struct pipe_dev_s *pipecommon_allocdev(void)
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{
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struct pipe_dev_s *dev;
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2008-07-26 14:02:46 +00:00
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/* Allocate a private structure to manage the pipe */
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2008-07-26 13:12:11 +00:00
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dev = (struct pipe_dev_s *)malloc(sizeof(struct pipe_dev_s));
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if (dev)
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{
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/* Initialize the private structure */
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memset(&dev->s, 0, sizeof(struct pipe_state_s));
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sem_init(&dev->s.d_bfsem, 0, 1);
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sem_init(&dev->s.d_rdsem, 0, 0);
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sem_init(&dev->s.d_wrsem, 0, 0);
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}
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return dev;
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}
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/****************************************************************************
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* Name: pipecommon_freedev
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****************************************************************************/
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2008-07-26 20:40:49 +00:00
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void pipecommon_freedev(FAR struct pipe_dev_s *dev)
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2008-07-26 13:12:11 +00:00
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{
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sem_destroy(&dev->s.d_bfsem);
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sem_destroy(&dev->s.d_rdsem);
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sem_destroy(&dev->s.d_wrsem);
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free(dev);
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}
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/****************************************************************************
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* Name: pipecommon_open
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****************************************************************************/
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int pipecommon_open(FAR struct file *filep)
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{
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struct inode *inode = filep->f_inode;
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struct pipe_dev_s *dev = inode->i_private;
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2008-07-26 14:24:17 +00:00
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int sval;
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2008-07-26 13:12:11 +00:00
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/* Some sanity checking */
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#if CONFIG_DEBUG
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if (!dev)
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{
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return -EBADF;
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}
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#endif
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/* Make sure that we have exclusive access to the device structure */
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if (sem_wait(&dev->s.d_bfsem) == 0)
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{
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/* Increment the reference count on the pipe instance */
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dev->s.d_refs++;
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/* If opened for writing, increment the count of writers on on the pipe instance */
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if ((filep->f_oflags & O_WROK) != 0)
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{
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dev->s.d_nwriters++;
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2008-07-26 14:24:17 +00:00
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/* If this this is the first writer, then the read semaphore indicates the
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* number of readers waiting for the first writer. Wake them all up.
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*/
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if (dev->s.d_nwriters == 1)
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{
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while (sem_getvalue(&dev->s.d_rdsem, &sval) == 0 && sval < 0)
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{
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sem_post(&dev->s.d_rdsem);
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}
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}
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2008-07-26 13:12:11 +00:00
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}
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2008-07-26 14:02:46 +00:00
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/* If opened for read-only, then wait for at least one writer on the pipe */
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2008-07-26 14:24:17 +00:00
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sched_lock();
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2008-07-26 13:12:11 +00:00
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(void)sem_post(&dev->s.d_bfsem);
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2008-07-26 20:40:49 +00:00
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if ((filep->f_oflags & O_RDWR) == O_RDONLY && dev->s.d_nwriters < 1)
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2008-07-26 14:24:17 +00:00
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{
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/* NOTE: d_rdsem is normally used when the read logic waits for more
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* data to be written. But until the first writer has opened the
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* pipe, the meaning is different: it is used prevent O_RDONLY open
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* calls from returning until there is at least one writer on the pipe.
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* This is required both by spec and also because it prevents
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* subsequent read() calls from returning end-of-file because there is
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* no writer on the pipe.
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*/
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pipecommon_semtake(&dev->s.d_rdsem);
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}
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sched_unlock();
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2008-07-26 13:12:11 +00:00
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return OK;
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}
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return ERROR;
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}
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/****************************************************************************
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* Name: pipecommon_close
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****************************************************************************/
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int pipecommon_close(FAR struct file *filep)
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{
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struct inode *inode = filep->f_inode;
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struct pipe_dev_s *dev = inode->i_private;
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2008-07-26 14:02:46 +00:00
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int sval;
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2008-07-26 13:12:11 +00:00
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/* Some sanity checking */
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#if CONFIG_DEBUG
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if (!dev)
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{
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return -EBADF;
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}
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#endif
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/* Make sure that we have exclusive access to the device structure.
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* NOTE: close() is supposed to return EINTR if interrupted, however
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* I've never seen anyone check that.
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*/
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pipecommon_semtake(&dev->s.d_bfsem);
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2008-07-26 20:47:39 +00:00
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/* Check if the decremented reference count would be less than zero */
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2008-07-26 13:12:11 +00:00
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2008-07-26 20:47:39 +00:00
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if (dev->s.d_refs > 0)
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2008-07-26 13:12:11 +00:00
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{
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/* No.. then just decrement the reference count */
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dev->s.d_refs--;
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/* If opened for writing, decrement the count of writers on on the pipe instance */
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if ((filep->f_oflags & O_WROK) != 0)
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{
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2008-07-26 14:02:46 +00:00
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/* If there are no longer any writers on the pipe, then notify all of the
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* waiting readers that they must return end-of-file.
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2008-07-26 13:12:11 +00:00
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*/
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2008-07-26 14:02:46 +00:00
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if (--dev->s.d_nwriters <= 0)
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2008-07-26 13:12:11 +00:00
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{
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2008-07-26 14:02:46 +00:00
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while (sem_getvalue(&dev->s.d_rdsem, &sval) == 0 && sval < 0)
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{
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sem_post(&dev->s.d_rdsem);
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}
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2008-07-26 13:12:11 +00:00
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}
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}
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}
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2008-07-26 20:40:49 +00:00
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sem_post(&dev->s.d_bfsem);
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2008-07-26 13:12:11 +00:00
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return OK;
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}
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/****************************************************************************
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* Name: pipecommon_read
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****************************************************************************/
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ssize_t pipecommon_read(FAR struct file *filep, FAR char *buffer, size_t len)
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{
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struct inode *inode = filep->f_inode;
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struct pipe_dev_s *dev = inode->i_private;
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ssize_t nread = 0;
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2008-07-26 14:02:46 +00:00
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int sval;
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2008-07-26 13:12:11 +00:00
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int ret;
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/* Some sanity checking */
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#if CONFIG_DEBUG
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if (!dev)
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{
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return -ENODEV;
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}
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#endif
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/* Make sure that we have exclusive access to the device structure */
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if (sem_wait(&dev->s.d_bfsem) < 0)
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{
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return ERROR;
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}
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2008-07-26 14:02:46 +00:00
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/* If the pipe is empty, then wait for something to be written to it */
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2008-07-26 13:12:11 +00:00
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while (dev->s.d_wrndx == dev->s.d_rdndx)
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{
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/* If O_NONBLOCK was set, then return EGAIN */
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if (filep->f_oflags & O_NONBLOCK)
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{
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sem_post(&dev->s.d_bfsem);
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return -EAGAIN;
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}
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/* If there are no writers on the pipe, then return end of file */
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if (dev->s.d_nwriters <= 0)
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{
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sem_post(&dev->s.d_bfsem);
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return 0;
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}
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2008-07-26 14:02:46 +00:00
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/* Otherwise, wait for something to be written to the pipe */
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2008-07-26 13:12:11 +00:00
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sched_lock();
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sem_post(&dev->s.d_bfsem);
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ret = sem_wait(&dev->s.d_rdsem);
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sched_unlock();
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if (ret < 0 || sem_wait(&dev->s.d_bfsem) < 0)
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{
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return ERROR;
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}
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}
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2008-07-26 14:02:46 +00:00
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/* Then return whatever is available in the pipe (which is at least one byte) */
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2008-07-26 13:12:11 +00:00
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nread = 0;
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while (nread < len && dev->s.d_wrndx != dev->s.d_rdndx)
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{
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*buffer++ = dev->d_buffer[dev->s.d_rdndx];
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2008-07-26 14:02:46 +00:00
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if (++dev->s.d_rdndx >= CONFIG_DEV_PIPE_SIZE)
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2008-07-26 13:12:11 +00:00
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{
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dev->s.d_rdndx = 0;
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}
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nread++;
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}
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2008-07-26 14:02:46 +00:00
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/* Notify all waiting writers that bytes have been removed from the buffer */
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2008-07-26 13:12:11 +00:00
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2008-07-26 14:02:46 +00:00
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while (sem_getvalue(&dev->s.d_wrsem, &sval) == 0 && sval < 0)
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2008-07-26 13:12:11 +00:00
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{
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sem_post(&dev->s.d_wrsem);
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}
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sem_post(&dev->s.d_bfsem);
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return nread;
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}
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/****************************************************************************
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* Name: pipecommon_write
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****************************************************************************/
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ssize_t pipecommon_write(FAR struct file *filep, FAR const char *buffer, size_t len)
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{
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struct inode *inode = filep->f_inode;
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struct pipe_dev_s *dev = inode->i_private;
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ssize_t nwritten = 0;
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ssize_t last;
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int nxtwrndx;
|
2008-07-26 14:02:46 +00:00
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int sval;
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2008-07-26 13:12:11 +00:00
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/* Some sanity checking */
|
|
|
|
#if CONFIG_DEBUG
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|
if (!dev)
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{
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return -ENODEV;
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}
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#endif
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|
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/* Make sure that we have exclusive access to the device structure */
|
|
|
|
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if (sem_wait(&dev->s.d_bfsem) < 0)
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{
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return ERROR;
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}
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/* Loop until all of the bytes have been written */
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last = 0;
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for (;;)
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{
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/* Calculate the write index AFTER the next byte is written */
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|
nxtwrndx = dev->s.d_wrndx + 1;
|
2008-07-26 14:02:46 +00:00
|
|
|
if (nxtwrndx >= CONFIG_DEV_PIPE_SIZE)
|
2008-07-26 13:12:11 +00:00
|
|
|
{
|
|
|
|
nxtwrndx = 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Would the next write overflow the circular buffer? */
|
|
|
|
|
|
|
|
if (nxtwrndx != dev->s.d_rdndx)
|
|
|
|
{
|
|
|
|
/* No... copy the byte */
|
|
|
|
|
|
|
|
dev->d_buffer[dev->s.d_wrndx] = *buffer++;
|
|
|
|
dev->s.d_wrndx = nxtwrndx;
|
|
|
|
|
|
|
|
/* Is the write complete? */
|
|
|
|
|
|
|
|
if (++nwritten >= len)
|
|
|
|
{
|
2008-07-26 14:02:46 +00:00
|
|
|
/* Yes.. Notify all of the waiting readers that more data is available */
|
2008-07-26 13:12:11 +00:00
|
|
|
|
2008-07-26 14:02:46 +00:00
|
|
|
while (sem_getvalue(&dev->s.d_rdsem, &sval) == 0 && sval < 0)
|
2008-07-26 13:12:11 +00:00
|
|
|
{
|
|
|
|
sem_post(&dev->s.d_rdsem);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Return the number of bytes written */
|
|
|
|
|
|
|
|
sem_post(&dev->s.d_bfsem);
|
|
|
|
return len;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
/* There is not enough room for the next byte. Was anything written in this pass? */
|
|
|
|
|
|
|
|
if (last < nwritten)
|
|
|
|
{
|
2008-07-26 14:02:46 +00:00
|
|
|
/* Yes.. Notify all of the waiting readers that more data is available */
|
2008-07-26 13:12:11 +00:00
|
|
|
|
2008-07-26 14:02:46 +00:00
|
|
|
while (sem_getvalue(&dev->s.d_rdsem, &sval) == 0 && sval < 0)
|
2008-07-26 13:12:11 +00:00
|
|
|
{
|
|
|
|
sem_post(&dev->s.d_rdsem);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
last = nwritten;
|
|
|
|
|
|
|
|
/* If O_NONBLOCK was set, then return partial bytes written or EGAIN */
|
|
|
|
|
|
|
|
if (filep->f_oflags & O_NONBLOCK)
|
|
|
|
{
|
|
|
|
if (nwritten == 0)
|
|
|
|
{
|
|
|
|
nwritten = -EAGAIN;
|
|
|
|
}
|
|
|
|
sem_post(&dev->s.d_bfsem);
|
|
|
|
return nwritten;
|
|
|
|
}
|
|
|
|
|
2008-07-26 14:02:46 +00:00
|
|
|
/* There is more to be written.. wait for data to be removed from the pipe */
|
2008-07-26 13:12:11 +00:00
|
|
|
|
|
|
|
sched_lock();
|
|
|
|
sem_post(&dev->s.d_bfsem);
|
|
|
|
pipecommon_semtake(&dev->s.d_wrsem);
|
|
|
|
sched_unlock();
|
|
|
|
pipecommon_semtake(&dev->s.d_bfsem);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2008-07-26 14:02:46 +00:00
|
|
|
#endif /* CONFIG_DEV_PIPE_SIZE > 0 */
|