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incubator-nuttx/drivers/rwbuffer.c

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/****************************************************************************
* drivers/rwbuffer.c
*
* Copyright (C) 2009, 2011, 2013-2014 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 <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <assert.h>
#include <semaphore.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/wqueue.h>
#include <nuttx/drivers/rwbuffer.h>
#if defined(CONFIG_DRVR_WRITEBUFFER) || defined(CONFIG_DRVR_READAHEAD)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#ifndef CONFIG_SCHED_WORKQUEUE
# error "Worker thread support is required (CONFIG_SCHED_WORKQUEUE)"
#endif
#ifndef CONFIG_DRVR_WRDELAY
# define CONFIG_DRVR_WRDELAY 350
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: rwb_semtake
****************************************************************************/
static void rwb_semtake(sem_t *sem)
{
/* Take the semaphore (perhaps waiting) */
while (sem_wait(sem) != 0)
{
/* The only case that an error should occur here is if
* the wait was awakened by a signal.
*/
ASSERT(get_errno() == EINTR);
}
}
/****************************************************************************
* Name: rwb_semgive
****************************************************************************/
#define rwb_semgive(s) sem_post(s)
/****************************************************************************
* Name: rwb_overlap
****************************************************************************/
static inline bool rwb_overlap(off_t blockstart1, size_t nblocks1,
off_t blockstart2, size_t nblocks2)
{
off_t blockend1 = blockstart1 + nblocks1 - 1;
off_t blockend2 = blockstart2 + nblocks2 - 1;
/* If the buffer 1 is wholly outside of buffer 2, return false */
if ((blockend1 < blockstart2) || /* Wholly "below" */
(blockstart1 > blockend2)) /* Wholly "above" */
{
return false;
}
else
{
return true;
}
}
/****************************************************************************
* Name: rwb_resetwrbuffer
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
static inline void rwb_resetwrbuffer(struct rwbuffer_s *rwb)
{
/* We assume that the caller holds the wrsem */
rwb->wrnblocks = 0;
rwb->wrblockstart = (off_t)-1;
rwb->wrexpectedblock = (off_t)-1;
}
#endif
/****************************************************************************
* Name: rwb_wrflush
*
* Assumptions:
* The caller holds the wrsem semaphore.
*
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
static void rwb_wrflush(struct rwbuffer_s *rwb)
{
int ret;
finfo("Timeout!\n");
if (rwb->wrnblocks > 0)
{
finfo("Flushing: blockstart=0x%08lx nblocks=%d from buffer=%p\n",
(long)rwb->wrblockstart, rwb->wrnblocks, rwb->wrbuffer);
/* Flush cache. On success, the flush method will return the number
* of blocks written. Anything other than the number requested is
* an error.
*/
ret = rwb->wrflush(rwb->dev, rwb->wrbuffer, rwb->wrblockstart, rwb->wrnblocks);
if (ret != rwb->wrnblocks)
{
ferr("ERROR: Error flushing write buffer: %d\n", ret);
}
rwb_resetwrbuffer(rwb);
}
}
#endif
/****************************************************************************
* Name: rwb_wrtimeout
****************************************************************************/
static void rwb_wrtimeout(FAR void *arg)
{
/* The following assumes that the size of a pointer is 4-bytes or less */
FAR struct rwbuffer_s *rwb = (struct rwbuffer_s *)arg;
DEBUGASSERT(rwb != NULL);
/* If a timeout elapses with with write buffer activity, this watchdog
* handler function will be evoked on the thread of execution of the
* worker thread.
*/
rwb_semtake(&rwb->wrsem);
rwb_wrflush(rwb);
rwb_semgive(&rwb->wrsem);
}
/****************************************************************************
* Name: rwb_wrstarttimeout
****************************************************************************/
static void rwb_wrstarttimeout(FAR struct rwbuffer_s *rwb)
{
/* CONFIG_DRVR_WRDELAY provides the delay period in milliseconds. CLK_TCK
* provides the clock tick of the system (frequency in Hz).
*/
int ticks = (CONFIG_DRVR_WRDELAY + CLK_TCK/2) / CLK_TCK;
(void)work_queue(LPWORK, &rwb->work, rwb_wrtimeout, (FAR void *)rwb, ticks);
}
/****************************************************************************
* Name: rwb_wrcanceltimeout
****************************************************************************/
static inline void rwb_wrcanceltimeout(struct rwbuffer_s *rwb)
{
(void)work_cancel(LPWORK, &rwb->work);
}
/****************************************************************************
* Name: rwb_writebuffer
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
static ssize_t rwb_writebuffer(FAR struct rwbuffer_s *rwb,
off_t startblock, uint32_t nblocks,
FAR const uint8_t *wrbuffer)
{
int ret;
/* Write writebuffer Logic */
rwb_wrcanceltimeout(rwb);
/* First: Should we flush out our cache? We would do that if (1) we already
* buffering blocks and the next block writing is not in the same sequence,
* or (2) the number of blocks would exceed our allocated buffer capacity
*/
if (((startblock != rwb->wrexpectedblock) && (rwb->wrnblocks)) ||
((rwb->wrnblocks + nblocks) > rwb->wrmaxblocks))
{
finfo("writebuffer miss, expected: %08x, given: %08x\n",
rwb->wrexpectedblock, startblock);
/* Flush the write buffer */
ret = rwb->wrflush(rwb->dev, rwb->wrbuffer, rwb->wrblockstart, rwb->wrnblocks);
if (ret < 0)
{
ferr("ERROR: Error writing multiple from cache: %d\n", -ret);
return ret;
}
rwb_resetwrbuffer(rwb);
}
/* writebuffer is empty? Then initialize it */
if (rwb->wrnblocks == 0)
{
finfo("Fresh cache starting at block: 0x%08x\n", startblock);
rwb->wrblockstart = startblock;
}
/* Add data to cache */
finfo("writebuffer: copying %d bytes from %p to %p\n",
nblocks * rwb->blocksize, wrbuffer,
&rwb->wrbuffer[rwb->wrnblocks * rwb->blocksize]);
memcpy(&rwb->wrbuffer[rwb->wrnblocks * rwb->blocksize],
wrbuffer, nblocks * rwb->blocksize);
rwb->wrnblocks += nblocks;
rwb->wrexpectedblock = rwb->wrblockstart + rwb->wrnblocks;
rwb_wrstarttimeout(rwb);
return nblocks;
}
#endif
/****************************************************************************
* Name: rwb_resetrhbuffer
****************************************************************************/
#ifdef CONFIG_DRVR_READAHEAD
static inline void rwb_resetrhbuffer(struct rwbuffer_s *rwb)
{
/* We assume that the caller holds the readAheadBufferSemphore */
rwb->rhnblocks = 0;
rwb->rhblockstart = (off_t)-1;
}
#endif
/****************************************************************************
* Name: rwb_bufferread
****************************************************************************/
#ifdef CONFIG_DRVR_READAHEAD
static inline void
rwb_bufferread(struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, uint8_t **rdbuffer)
{
/* We assume that (1) the caller holds the readAheadBufferSemphore, and (2)
* that the caller already knows that all of the blocks are in the
* read-ahead buffer.
*/
/* Convert the units from blocks to bytes */
off_t blockoffset = startblock - rwb->rhblockstart;
off_t byteoffset = rwb->blocksize * blockoffset;
size_t nbytes = rwb->blocksize * nblocks;
/* Get the byte address in the read-ahead buffer */
uint8_t *rhbuffer = rwb->rhbuffer + byteoffset;
/* Copy the data from the read-ahead buffer into the IO buffer */
memcpy(*rdbuffer, rhbuffer, nbytes);
/* Update the caller's copy for the next address */
*rdbuffer += nbytes;
}
#endif
/****************************************************************************
* Name: rwb_rhreload
****************************************************************************/
#ifdef CONFIG_DRVR_READAHEAD
static int rwb_rhreload(struct rwbuffer_s *rwb, off_t startblock)
{
off_t endblock;
size_t nblocks;
int ret;
/* Check for attempts to read beyond the end of the media */
if (startblock >= rwb->nblocks)
{
return -ESPIPE;
}
/* Get the block number +1 of the last block that will fit in the
* read-ahead buffer
*/
endblock = startblock + rwb->rhmaxblocks;
/* Make sure that we don't read past the end of the device */
if (endblock > rwb->nblocks)
{
endblock = rwb->nblocks;
}
nblocks = endblock - startblock;
/* Reset the read buffer */
rwb_resetrhbuffer(rwb);
/* Now perform the read */
ret = rwb->rhreload(rwb->dev, rwb->rhbuffer, startblock, nblocks);
if (ret == nblocks)
{
/* Update information about what is in the read-ahead buffer */
rwb->rhnblocks = nblocks;
rwb->rhblockstart = startblock;
/* The return value is not the number of blocks we asked to be loaded. */
return nblocks;
}
return -EIO;
}
#endif
/****************************************************************************
* Name: rwb_invalidate_writebuffer
*
* Description:
* Invalidate a region of the write buffer
*
****************************************************************************/
#if defined(CONFIG_DRVR_WRITEBUFFER) && defined(CONFIG_DRVR_INVALIDATE)
int rwb_invalidate_writebuffer(FAR struct rwbuffer_s *rwb,
off_t startblock, size_t blockcount)
{
int ret;
if (rwb->wrmaxblocks > 0 && rwb->wrnblocks > 0)
{
off_t wrbend;
off_t invend;
finfo("startblock=%d blockcount=%p\n", startblock, blockcount);
rwb_semtake(&rwb->wrsem);
/* Now there are five cases:
*
* 1. We invalidate nothing
*/
wrbend = rwb->wrblockstart + rwb->wrnblocks;
invend = startblock + blockcount;
if (rwb->wrblockstart > invend || wrbend < startblock)
{
ret = OK;
}
/* 2. We invalidate the entire write buffer. */
else if (rwb->wrblockstart >= startblock && wrbend <= invend)
{
rwb->wrnblocks = 0;
ret = OK;
}
/* We are going to invalidate a subset of the write buffer. Three
* more cases to consider:
*
* 2. We invalidate a portion in the middle of the write buffer
*/
else if (rwb->wrblockstart < startblock && wrbend > invend)
{
uint8_t *src;
off_t block;
off_t offset;
size_t nblocks;
/* Write the blocks at the end of the media to hardware */
nblocks = wrbend - invend;
block = invend;
offset = block - rwb->wrblockstart;
src = rwb->wrbuffer + offset * rwb->blocksize;
ret = rwb->wrflush(rwb->dev, src, block, nblocks);
if (ret < 0)
{
ferr("ERROR: wrflush failed: %d\n", ret);
}
/* Keep the blocks at the beginning of the buffer up the
* start of the invalidated region.
*/
else
{
rwb->wrnblocks = startblock - rwb->wrblockstart;
ret = OK;
}
}
/* 3. We invalidate a portion at the end of the write buffer */
else if (wrbend > startblock && wrbend <= invend)
{
rwb->wrnblocks = wrbend - startblock;
ret = OK;
}
/* 4. We invalidate a portion at the beginning of the write buffer */
else /* if (rwb->wrblockstart >= startblock && wrbend > invend) */
{
uint8_t *src;
size_t ninval;
size_t nkeep;
DEBUGASSERT(rwb->wrblockstart >= startblock && wrbend > invend);
/* Copy the data from the uninvalidated region to the beginning
* of the write buffer.
*
* First calculate the source and destination of the transfer.
*/
ninval = invend - rwb->wrblockstart;
src = rwb->wrbuffer + ninval * rwb->blocksize;
/* Calculate the number of blocks we are keeping. We keep
* the ones that we don't invalidate.
*/
nkeep = rwb->wrnblocks - ninval;
/* Then move the data that we are keeping to the beginning
* the write buffer.
*/
memcpy(rwb->wrbuffer, src, nkeep * rwb->blocksize);
/* Update the block info. The first block is now the one just
* after the invalidation region and the number buffered blocks
* is the number that we kept.
*/
rwb->wrblockstart = invend;
rwb->wrnblocks = nkeep;
ret = OK;
}
rwb_semgive(&rwb->wrsem);
}
return ret;
}
#endif
/****************************************************************************
* Name: rwb_invalidate_readahead
*
* Description:
* Invalidate a region of the read-ahead buffer
*
****************************************************************************/
#if defined(CONFIG_DRVR_READAHEAD) && defined(CONFIG_DRVR_INVALIDATE)
int rwb_invalidate_readahead(FAR struct rwbuffer_s *rwb,
off_t startblock, size_t blockcount)
{
int ret;
if (rwb->rhmaxblocks > 0 && rwb->rhnblocks > 0)
{
off_t rhbend;
off_t invend;
finfo("startblock=%d blockcount=%p\n", startblock, blockcount);
rwb_semtake(&rwb->rhsem);
/* Now there are five cases:
*
* 1. We invalidate nothing
*/
rhbend = rwb->rhblockstart + rwb->rhnblocks;
invend = startblock + blockcount;
if (rhbend <= startblock || rwb->rhblockstart >= invend)
{
ret = OK;
}
/* 2. We invalidate the entire read-ahead buffer. */
else if (rwb->rhblockstart >= startblock && rhbend <= invend)
{
rwb->rhnblocks = 0;
ret = OK;
}
/* We are going to invalidate a subset of the read-ahead buffer.
* Three more cases to consider:
*
* 2. We invalidate a portion in the middle of the read-ahead buffer
*/
else if (rwb->rhblockstart < startblock && rhbend > invend)
{
/* Keep the blocks at the beginning of the buffer up the
* start of the invalidated region.
*/
rwb->rhnblocks = startblock - rwb->rhblockstart;
ret = OK;
}
/* 3. We invalidate a portion at the end of the read-ahead buffer */
else if (rhbend > startblock && rhbend <= invend)
{
rwb->rhnblocks = rhbend - startblock;
ret = OK;
}
/* 4. We invalidate a portion at the beginning of the write buffer */
else /* if (rwb->rhblockstart >= startblock && rhbend > invend) */
{
/* Let's just force the whole read-ahead buffer to be reloaded.
* That might cost s small amount of performance, but well worth
* the lower complexity.
*/
DEBUGASSERT(rwb->rhblockstart >= startblock && rhbend > invend);
rwb->rhnblocks = 0;
ret = OK;
}
rwb_semgive(&rwb->rhsem);
}
return ret;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: rwb_initialize
****************************************************************************/
int rwb_initialize(FAR struct rwbuffer_s *rwb)
{
uint32_t allocsize;
/* Sanity checking */
DEBUGASSERT(rwb != NULL);
DEBUGASSERT(rwb->blocksize > 0);
DEBUGASSERT(rwb->nblocks > 0);
DEBUGASSERT(rwb->dev != NULL);
/* Setup so that rwb_uninitialize can handle a failure */
#ifdef CONFIG_DRVR_WRITEBUFFER
DEBUGASSERT(rwb->wrflush != NULL);
rwb->wrbuffer = NULL;
#endif
#ifdef CONFIG_DRVR_READAHEAD
DEBUGASSERT(rwb->rhreload != NULL);
rwb->rhbuffer = NULL;
#endif
#ifdef CONFIG_DRVR_WRITEBUFFER
if (rwb->wrmaxblocks > 0)
{
finfo("Initialize the write buffer\n");
/* Initialize the write buffer access semaphore */
sem_init(&rwb->wrsem, 0, 1);
/* Initialize write buffer parameters */
rwb_resetwrbuffer(rwb);
/* Allocate the write buffer */
rwb->wrbuffer = NULL;
if (rwb->wrmaxblocks > 0)
{
allocsize = rwb->wrmaxblocks * rwb->blocksize;
rwb->wrbuffer = kmm_malloc(allocsize);
if (!rwb->wrbuffer)
{
ferr("Write buffer kmm_malloc(%d) failed\n", allocsize);
return -ENOMEM;
}
}
finfo("Write buffer size: %d bytes\n", allocsize);
}
#endif /* CONFIG_DRVR_WRITEBUFFER */
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
finfo("Initialize the read-ahead buffer\n");
/* Initialize the read-ahead buffer access semaphore */
sem_init(&rwb->rhsem, 0, 1);
/* Initialize read-ahead buffer parameters */
rwb_resetrhbuffer(rwb);
/* Allocate the read-ahead buffer */
rwb->rhbuffer = NULL;
if (rwb->rhmaxblocks > 0)
{
allocsize = rwb->rhmaxblocks * rwb->blocksize;
rwb->rhbuffer = kmm_malloc(allocsize);
if (!rwb->rhbuffer)
{
ferr("Read-ahead buffer kmm_malloc(%d) failed\n", allocsize);
return -ENOMEM;
}
}
finfo("Read-ahead buffer size: %d bytes\n", allocsize);
}
#endif /* CONFIG_DRVR_READAHEAD */
return OK;
}
/****************************************************************************
* Name: rwb_uninitialize
****************************************************************************/
void rwb_uninitialize(FAR struct rwbuffer_s *rwb)
{
#ifdef CONFIG_DRVR_WRITEBUFFER
if (rwb->wrmaxblocks > 0)
{
rwb_wrcanceltimeout(rwb);
sem_destroy(&rwb->wrsem);
if (rwb->wrbuffer)
{
kmm_free(rwb->wrbuffer);
}
}
#endif
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
sem_destroy(&rwb->rhsem);
if (rwb->rhbuffer)
{
kmm_free(rwb->rhbuffer);
}
}
#endif
}
/****************************************************************************
* Name: rwb_read
****************************************************************************/
ssize_t rwb_read(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR uint8_t *rdbuffer)
{
size_t remaining;
int ret = OK;
finfo("startblock=%ld nblocks=%ld rdbuffer=%p\n",
(long)startblock, (long)nblocks, rdbuffer);
#ifdef CONFIG_DRVR_WRITEBUFFER
/* If the new read data overlaps any part of the write buffer, then
* flush the write data onto the physical media before reading. We
* could attempt some more exotic handling -- but this simple logic
* is well-suited for simple streaming applications.
*/
if (rwb->wrmaxblocks > 0)
{
/* If the write buffer overlaps the block(s) requested, then flush the
* write buffer.
*/
rwb_semtake(&rwb->wrsem);
if (rwb_overlap(rwb->wrblockstart, rwb->wrnblocks, startblock, nblocks))
{
rwb_wrflush(rwb);
}
rwb_semgive(&rwb->wrsem);
}
#endif
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
/* Loop until we have read all of the requested blocks */
rwb_semtake(&rwb->rhsem);
for (remaining = nblocks; remaining > 0; )
{
/* Is there anything in the read-ahead buffer? */
if (rwb->rhnblocks > 0)
{
off_t bufferend;
/* How many blocks are available in this buffer? */
bufferend = rwb->rhblockstart + rwb->rhnblocks;
if (startblock >= rwb->rhblockstart && startblock < bufferend)
{
size_t rdblocks = bufferend - startblock;
if (rdblocks > remaining)
{
rdblocks = remaining;
}
/* Then read the data from the read-ahead buffer */
rwb_bufferread(rwb, startblock, rdblocks, &rdbuffer);
startblock += rdblocks;
remaining -= rdblocks;
}
}
/* If we did not get all of the data from the buffer, then we have
* to refill the buffer and try again.
*/
if (remaining > 0)
{
ret = rwb_rhreload(rwb, startblock);
if (ret < 0)
{
ferr("ERROR: Failed to fill the read-ahead buffer: %d\n", ret);
return (ssize_t)ret;
}
}
}
/* On success, return the number of blocks that we were requested to
* read. This is for compatibility with the normal return of a block
* driver read method
*/
rwb_semgive(&rwb->rhsem);
ret = nblocks;
}
else
#else
{
/* No read-ahead buffering, (re)load the data directly into
* the user buffer.
*/
ret = rwb->rhreload(rwb->dev, rdbuffer, startblock, nblocks);
}
#endif
return (ssize_t)ret;
}
/****************************************************************************
* Name: rwb_write
****************************************************************************/
ssize_t rwb_write(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR const uint8_t *wrbuffer)
{
int ret = OK;
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
/* If the new write data overlaps any part of the read buffer, then
* flush the data from the read buffer. We could attempt some more
* exotic handling -- but this simple logic is well-suited for simple
* streaming applications.
*/
rwb_semtake(&rwb->rhsem);
if (rwb_overlap(rwb->rhblockstart, rwb->rhnblocks, startblock, nblocks))
{
rwb_resetrhbuffer(rwb);
}
rwb_semgive(&rwb->rhsem);
}
#endif
#ifdef CONFIG_DRVR_WRITEBUFFER
if (rwb->wrmaxblocks > 0)
{
finfo("startblock=%d wrbuffer=%p\n", startblock, wrbuffer);
/* Use the block cache unless the buffer size is bigger than block cache */
if (nblocks > rwb->wrmaxblocks)
{
/* First flush the cache */
rwb_semtake(&rwb->wrsem);
rwb_wrflush(rwb);
rwb_semgive(&rwb->wrsem);
/* Then transfer the data directly to the media */
ret = rwb->wrflush(rwb->dev, wrbuffer, startblock, nblocks);
}
else
{
/* Buffer the data in the write buffer */
ret = rwb_writebuffer(rwb, startblock, nblocks, wrbuffer);
}
/* On success, return the number of blocks that we were requested to
* write. This is for compatibility with the normal return of a block
* driver write method
*/
}
else
#else
{
/* No write buffer.. just pass the write operation through via the
* flush callback.
*/
ret = rwb->wrflush(rwb->dev, wrbuffer, startblock, nblocks);
}
#endif
return (ssize_t)ret;
}
/****************************************************************************
* Name: rwb_readbytes
*
* Description:
* Character-oriented read
*
****************************************************************************/
#ifdef CONFIG_DRVR_READBYTES
ssize_t rwb_readbytes(FAR struct rwbuffer_s *dev, off_t offset,
size_t nbytes, FAR uint8_t *buffer)
{
/* Loop while there are bytes still be be read */
/* Make sure that the sector containing the next bytes to transfer is in
* memory.
*/
/* How many bytes can be transfer from the in-memory data? */
/* Transfer the bytes */
/* Adjust counts and offsets for the next time through the loop */
#warning Not Implemented
return -ENOSYS;
}
#endif
/****************************************************************************
* Name: rwb_mediaremoved
*
* Description:
* The following function is called when media is removed
*
****************************************************************************/
#ifdef CONFIG_DRVR_REMOVABLE
int rwb_mediaremoved(FAR struct rwbuffer_s *rwb)
{
#ifdef CONFIG_DRVR_WRITEBUFFER
if (rwb->wrmaxblocks > 0)
{
rwb_semtake(&rwb->wrsem);
rwb_resetwrbuffer(rwb);
rwb_semgive(&rwb->wrsem);
}
#endif
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
rwb_semtake(&rwb->rhsem);
rwb_resetrhbuffer(rwb);
rwb_semgive(&rwb->rhsem);
}
#endif
return OK;
}
#endif
/****************************************************************************
* Name: rwb_invalidate
*
* Description:
* Invalidate a region of the caches
*
****************************************************************************/
#ifdef CONFIG_DRVR_INVALIDATE
int rwb_invalidate(FAR struct rwbuffer_s *rwb,
off_t startblock, size_t blockcount)
{
int ret;
#ifdef CONFIG_DRVR_WRITEBUFFER
ret = rwb_invalidate_writebuffer(rwb, startblock, blockcount);
if (ret < 0)
{
ferr("ERROR: rwb_invalidate_writebuffer failed: %d\n", ret);
return ret;
}
#endif
#ifdef CONFIG_DRVR_READAHEAD
ret = rwb_invalidate_readahead(rwb, startblock, blockcount);
if (ret < 0)
{
ferr("ERROR: rwb_invalidate_readahead failed: %d\n", ret);
return ret;
}
#endif
return OK;
}
#endif
#endif /* CONFIG_DRVR_WRITEBUFFER || CONFIG_DRVR_READAHEAD */
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