212 lines
7.6 KiB
C
212 lines
7.6 KiB
C
/****************************************************************************
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* include/nuttx/rwbuffer.h
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*
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* Copyright (C) 2009, 2014 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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#ifndef __INCLUDE_NUTTX_RWBUFFER_H
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#define __INCLUDE_NUTTX_RWBUFFER_H
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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 <stdint.h>
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#include <semaphore.h>
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#include <nuttx/wqueue.h>
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#if defined(CONFIG_DRVR_WRITEBUFFER) || defined(CONFIG_DRVR_READAHEAD)
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/**********************************************************************
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* Pre-processor Definitions
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**********************************************************************/
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/**********************************************************************
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* Public Types
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**********************************************************************/
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/* Data transfer callouts. These must be provided by the block driver
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* logic in order to flush the write buffer when appropriate or to
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* reload the read-ahead buffer, when appropriate.
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*/
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typedef ssize_t (*rwbreload_t)(FAR void *dev, FAR uint8_t *buffer,
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off_t startblock, size_t nblocks);
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typedef ssize_t (*rwbflush_t)(FAR void *dev, FAR const uint8_t *buffer,
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off_t startblock, size_t nblocks);
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/* This structure holds the state of the buffers. In typical usage,
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* an instance of this structure is declared within each block driver
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* status structure like:
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*
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* struct foo_dev_s
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* {
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* ...
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* struct rwbuffer_s rwbuffer;
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* ...
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* };
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*
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* Note that this supports buffering for multiple block devices or for
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* multiple instances of same block device, because each rwbuffer instance
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* supports independent buffering.
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*
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* A reference to the struct rwbuffer_s instance is then passed to each
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* interface like:
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*
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* struct foo_dev_s *priv;
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* ...
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* ... [Setup blocksize, nblocks, dev, wrmaxblocks, wrflush,
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* rhmaxblocks, rhreload] ...
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* ret = rwb_initialize(&priv->rwbuffer);
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*/
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struct rwbuffer_s
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{
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/********************************************************************/
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/* These values must be provided by the user prior to calling
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* rwb_initialize()
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*/
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/* Supported geometry */
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uint16_t blocksize; /* The size of one block */
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size_t nblocks; /* The total number blocks supported */
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/* Read-ahead/Write buffer sizes. Buffering can be disabled (even if it
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* is enabled in the configuration) by setting the buffer size to zero
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* blocks.
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*/
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#ifdef CONFIG_DRVR_WRITEBUFFER
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uint16_t wrmaxblocks; /* The number of blocks to buffer in memory */
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#endif
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#ifdef CONFIG_DRVR_READAHEAD
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uint16_t rhmaxblocks; /* The number of blocks to buffer in memory */
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#endif
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/* Callback functions.
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*
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* wrflush. This callback is normally used to flush the contents of
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* the write buffer. If write buffering is disabled, then this
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* function will instead be used to perform unbuffered writes.
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* rhrelad. This callback is normally used to read new data into the
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* read-ahead buffer. If read-ahead buffering is disabled, then this
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* function will instead be used to perform unbuffered reads.
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*/
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FAR void *dev; /* Device state passed to callout functions */
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rwbflush_t wrflush; /* Callout to flush the write buffer */
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rwbreload_t rhreload; /* Callout to reload the read-ahead buffer */
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/********************************************************************/
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/* The user should never modify any of the remaining fields */
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/* This is the state of the write buffering */
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#ifdef CONFIG_DRVR_WRITEBUFFER
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sem_t wrsem; /* Enforces exclusive access to the write buffer */
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struct work_s work; /* Delayed work to flush buffer after a delay with no activity */
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uint8_t *wrbuffer; /* Allocated write buffer */
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uint16_t wrnblocks; /* Number of blocks in write buffer */
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off_t wrblockstart; /* First block in write buffer */
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off_t wrexpectedblock; /* Next block expected */
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#endif
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/* This is the state of the read-ahead buffering */
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#ifdef CONFIG_DRVR_READAHEAD
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sem_t rhsem; /* Enforces exclusive access to the write buffer */
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uint8_t *rhbuffer; /* Allocated read-ahead buffer */
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uint16_t rhnblocks; /* Number of blocks in read-ahead buffer */
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off_t rhblockstart; /* First block in read-ahead buffer */
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#endif
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};
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/**********************************************************************
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* Global Variables
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**********************************************************************/
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#undef EXTERN
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#if defined(__cplusplus)
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#define EXTERN extern "C"
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extern "C"
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{
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#else
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#define EXTERN extern
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#endif
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/**********************************************************************
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* Global Function Prototypes
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**********************************************************************/
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/* Buffer initialization */
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int rwb_initialize(FAR struct rwbuffer_s *rwb);
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void rwb_uninitialize(FAR struct rwbuffer_s *rwb);
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/* Block oriented transfers */
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ssize_t rwb_read(FAR struct rwbuffer_s *rwb, off_t startblock,
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size_t blockcount, FAR uint8_t *rdbuffer);
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ssize_t rwb_write(FAR struct rwbuffer_s *rwb,
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off_t startblock, size_t blockcount,
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FAR const uint8_t *wrbuffer);
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/* Character oriented transfers */
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#ifdef CONFIG_DRVR_READBYTES
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ssize_t rwb_readbytes(FAR struct rwbuffer_s *dev, off_t offset,
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size_t nbytes, FAR uint8_t *buffer);
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#endif
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/* Media events */
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#ifdef CONFIG_DRVR_REMOVABLE
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int rwb_mediaremoved(FAR struct rwbuffer_s *rwb);
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#endif
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#ifdef CONFIG_DRVR_INVALIDATE
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int rwb_invalidate(FAR struct rwbuffer_s *rwb,
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off_t startblock, size_t blockcount);
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#endif
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#undef EXTERN
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#if defined(__cplusplus)
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}
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#endif
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#endif /* CONFIG_DRVR_WRITEBUFFER || CONFIG_DRVR_READAHEAD */
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#endif /* __INCLUDE_NUTTX_RWBUFFER_H */
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