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incubator-nuttx/drivers/rwbuffer.c

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/****************************************************************************
* drivers/rwbuffer.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* 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 <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/semaphore.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_DRVR_WRDELAY
# define CONFIG_DRVR_WRDELAY 350
#endif
#if !defined(CONFIG_SCHED_WORKQUEUE) && CONFIG_DRVR_WRDELAY != 0
# error "Worker thread support is required (CONFIG_SCHED_WORKQUEUE)"
#endif
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static ssize_t rwb_read_(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR uint8_t *rdbuffer);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: rwb_semtake
****************************************************************************/
static int rwb_semtake(FAR sem_t *sem)
{
return nxsem_wait_uninterruptible(sem);
}
/****************************************************************************
* Name: rwb_forcetake
****************************************************************************/
static int rwb_forcetake(FAR sem_t *sem)
{
int result;
int ret = OK;
do
{
result = rwb_semtake(sem);
/* The only expected failure is if the thread is canceled */
DEBUGASSERT(result == OK || result == -ECANCELED);
if (ret == OK && result < 0)
{
/* Remember the first error */
ret = result;
}
}
while (result < 0);
return ret;
}
/****************************************************************************
* Name: rwb_semgive
****************************************************************************/
#define rwb_semgive(s) nxsem_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(FAR struct rwbuffer_s *rwb)
{
/* We assume that the caller holds the wrsem */
rwb->wrnblocks = 0;
rwb->wrblockstart = -1;
}
#endif
/****************************************************************************
* Name: rwb_wrflush
*
* Assumptions:
* The caller holds the wrsem semaphore.
*
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
static void rwb_wrflush(FAR struct rwbuffer_s *rwb)
{
int ret;
if (rwb->wrnblocks > 0)
{
size_t padblocks;
finfo("Flushing: blockstart=0x%08lx nblocks=%d from buffer=%p\n",
(long)rwb->wrblockstart, rwb->wrnblocks, rwb->wrbuffer);
padblocks = rwb->wrnblocks % rwb->wralignblocks;
if (padblocks)
{
padblocks = rwb->wralignblocks - padblocks;
rwb_read_(rwb, rwb->wrblockstart + rwb->wrnblocks, padblocks,
&rwb->wrbuffer[rwb->wrnblocks * rwb->blocksize]);
rwb->wrnblocks += padblocks;
}
/* 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
****************************************************************************/
#if defined(CONFIG_DRVR_WRITEBUFFER) && CONFIG_DRVR_WRDELAY != 0
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 = (FAR struct rwbuffer_s *)arg;
DEBUGASSERT(rwb != NULL);
finfo("Timeout!\n");
/* If a timeout elapses with write buffer activity, this watchdog
* handler function will be evoked on the thread of execution of the
* worker thread.
*/
rwb_forcetake(&rwb->wrsem);
rwb_wrflush(rwb);
rwb_semgive(&rwb->wrsem);
}
#endif
/****************************************************************************
* Name: rwb_wrstarttimeout
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
static void rwb_wrstarttimeout(FAR struct rwbuffer_s *rwb)
{
#if CONFIG_DRVR_WRDELAY != 0
/* CONFIG_DRVR_WRDELAY provides the delay period in milliseconds. CLK_TCK
* provides the clock tick of the system (frequency in Hz).
*/
int ticks = MSEC2TICK(CONFIG_DRVR_WRDELAY);
work_queue(LPWORK, &rwb->work, rwb_wrtimeout, (FAR void *)rwb, ticks);
#endif
}
#endif
/****************************************************************************
* Name: rwb_wrcanceltimeout
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
static inline void rwb_wrcanceltimeout(FAR struct rwbuffer_s *rwb)
{
#if CONFIG_DRVR_WRDELAY != 0
work_cancel(LPWORK, &rwb->work);
#endif
}
#endif
/****************************************************************************
* 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)
{
uint32_t nwritten = nblocks;
/* Write writebuffer Logic */
rwb_wrcanceltimeout(rwb);
/* Is data saved in the write buffer? */
if (rwb->wrnblocks > 0)
{
off_t wrbend;
off_t newend;
/* Now there are five cases:
*
* 1. We update the non-overlapping region
*/
wrbend = rwb->wrblockstart + rwb->wrnblocks;
newend = startblock + nblocks;
if (wrbend < startblock || rwb->wrblockstart > newend)
{
/* Nothing to do */;
}
/* 2. We update the entire write buffer. */
else if (rwb->wrblockstart > startblock && wrbend < newend)
{
rwb->wrnblocks = 0;
}
/* We are going to update a subset of the write buffer. Three
* more cases to consider:
*
* 3. We update a portion in the middle of the write buffer
*/
else if (rwb->wrblockstart <= startblock && wrbend >= newend)
{
FAR uint8_t *dest;
size_t offset;
/* Copy the data to the middle of write buffer */
offset = startblock - rwb->wrblockstart;
dest = rwb->wrbuffer + offset * rwb->blocksize;
memcpy(dest, wrbuffer, nblocks * rwb->blocksize);
nblocks = 0;
}
/* 4. We upate a portion at the end of the write buffer */
else if (wrbend >= startblock && wrbend <= newend)
{
FAR uint8_t *dest;
size_t offset;
size_t ncopy;
/* Copy the data from the updating region to the end
* of the write buffer.
*/
offset = rwb->wrnblocks - (wrbend - startblock);
ncopy = rwb->wrmaxblocks - offset;
if (ncopy > nblocks)
{
ncopy = nblocks;
}
dest = rwb->wrbuffer + offset * rwb->blocksize;
memcpy(dest, wrbuffer, ncopy * rwb->blocksize);
rwb->wrnblocks = offset + ncopy;
wrbuffer += ncopy * rwb->blocksize;
startblock += ncopy;
nblocks -= ncopy;
}
/* 5. We update a portion at the beginning of the write buffer */
else /* if (rwb->wrblockstart >= startblock && wrbend >= newend) */
{
FAR uint8_t *dest;
FAR const uint8_t *src;
size_t ncopy;
DEBUGASSERT(rwb->wrblockstart >= startblock && wrbend >= newend);
/* Move the cached data to the end of the write buffer */
ncopy = rwb->wrblockstart - startblock;
if (ncopy > rwb->wrmaxblocks - rwb->wrnblocks)
{
ncopy = rwb->wrmaxblocks - rwb->wrnblocks;
}
dest = rwb->wrbuffer + ncopy * rwb->blocksize;
memmove(dest, rwb->wrbuffer, ncopy * rwb->blocksize);
rwb->wrblockstart -= ncopy;
rwb->wrnblocks += ncopy;
/* Copy the data from the updating region to the beginning
* of the write buffer.
*/
ncopy = newend - rwb->wrblockstart;
src = wrbuffer + (nblocks - ncopy) * rwb->blocksize;
memcpy(rwb->wrbuffer, src, ncopy * rwb->blocksize);
nblocks -= ncopy;
}
}
/* Use the block cache unless the buffer size is bigger than block cache */
if (nblocks > rwb->wrmaxblocks)
{
ssize_t ret = rwb->wrflush(rwb->dev, wrbuffer, startblock, nblocks);
if (ret < 0)
{
return ret;
}
}
else if (nblocks)
{
/* Flush the write buffer */
rwb_wrflush(rwb);
/* Buffer the data in the write buffer */
memcpy(rwb->wrbuffer, wrbuffer, nblocks * rwb->blocksize);
rwb->wrblockstart = startblock;
rwb->wrnblocks = nblocks;
}
if (rwb->wrnblocks > 0)
{
rwb_wrstarttimeout(rwb);
}
return nwritten;
}
#endif
/****************************************************************************
* Name: rwb_resetrhbuffer
****************************************************************************/
#ifdef CONFIG_DRVR_READAHEAD
static inline void rwb_resetrhbuffer(FAR struct rwbuffer_s *rwb)
{
/* We assume that the caller holds the readAheadBufferSemphore */
rwb->rhnblocks = 0;
rwb->rhblockstart = -1;
}
#endif
/****************************************************************************
* Name: rwb_bufferread
****************************************************************************/
#ifdef CONFIG_DRVR_READAHEAD
static inline void
rwb_bufferread(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR uint8_t **rdbuffer)
{
FAR uint8_t *rhbuffer;
/* 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 */
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(FAR 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 = OK;
/* Is there a write buffer? Is data saved in the write buffer? */
if (rwb->wrmaxblocks > 0 && rwb->wrnblocks > 0)
{
off_t wrbend;
off_t invend;
finfo("startblock=%d blockcount=%p\n", startblock, blockcount);
ret = rwb_semtake(&rwb->wrsem);
if (ret < 0)
{
return ret;
}
/* Now there are five cases:
*
* 1. We invalidate nothing
*/
wrbend = rwb->wrblockstart + rwb->wrnblocks;
invend = startblock + blockcount;
if (wrbend <= startblock || rwb->wrblockstart >= invend)
{
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:
*
* 3. We invalidate a portion in the middle of the write buffer
*/
else if (rwb->wrblockstart < startblock && wrbend > invend)
{
FAR 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;
}
}
/* 4. We invalidate a portion at the end of the write buffer */
else if (wrbend > startblock && wrbend <= invend)
{
rwb->wrnblocks -= wrbend - startblock;
ret = OK;
}
/* 5. We invalidate a portion at the beginning of the write buffer */
else /* if (rwb->wrblockstart >= startblock && wrbend > invend) */
{
FAR 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 = OK;
if (rwb->rhmaxblocks > 0 && rwb->rhnblocks > 0)
{
off_t rhbend;
off_t invend;
finfo("startblock=%d blockcount=%p\n", startblock, blockcount);
ret = rwb_semtake(&rwb->rhsem);
if (ret < 0)
{
return ret;
}
/* 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 begin of the read-ahead buffer */
else /* if (rwb->rhblockstart >= startblock && rhbend > invend) */
{
FAR uint8_t *src;
size_t ninval;
size_t nkeep;
DEBUGASSERT(rwb->rhblockstart >= startblock && rhbend > invend);
/* Copy the data from the uninvalidated region to the beginning
* of the read buffer.
*
* First calculate the source and destination of the transfer.
*/
ninval = invend - rwb->rhblockstart;
src = rwb->rhbuffer + ninval * rwb->blocksize;
/* Calculate the number of blocks we are keeping. We keep
* the ones that we don't invalidate.
*/
nkeep = rwb->rhnblocks - ninval;
/* Then move the data that we are keeping to the beginning
* the read buffer.
*/
memmove(rwb->rhbuffer, 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->rhblockstart = invend;
rwb->rhnblocks = nkeep;
}
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");
if (rwb->wralignblocks == 0)
{
rwb->wralignblocks = 1;
}
DEBUGASSERT(rwb->wralignblocks <= rwb->wrmaxblocks &&
rwb->wrmaxblocks % rwb->wralignblocks == 0);
/* Initialize the write buffer access semaphore */
nxsem_init(&rwb->wrsem, 0, 1);
/* Initialize write buffer parameters */
rwb_resetwrbuffer(rwb);
/* Allocate the write buffer */
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 */
nxsem_init(&rwb->rhsem, 0, 1);
/* Initialize read-ahead buffer parameters */
rwb_resetrhbuffer(rwb);
/* Allocate the read-ahead buffer */
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);
rwb_wrflush(rwb);
nxsem_destroy(&rwb->wrsem);
if (rwb->wrbuffer)
{
kmm_free(rwb->wrbuffer);
}
}
#endif
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
nxsem_destroy(&rwb->rhsem);
if (rwb->rhbuffer)
{
kmm_free(rwb->rhbuffer);
}
}
#endif
}
/****************************************************************************
* Name: rwb_read_
****************************************************************************/
static ssize_t rwb_read_(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR uint8_t *rdbuffer)
{
int ret = OK;
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
size_t remaining;
ret = nxsem_wait(&rwb->rhsem);
if (ret < 0)
{
return ret;
}
/* Loop until we have read all of the requested blocks */
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);
rwb_semgive(&rwb->rhsem);
return 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
#endif
{
/* No read-ahead buffering, (re)load the data directly into
* the user buffer.
*/
ret = rwb->rhreload(rwb->dev, rdbuffer, startblock, nblocks);
}
return ret;
}
/****************************************************************************
* Name: rwb_read
****************************************************************************/
ssize_t rwb_read(FAR struct rwbuffer_s *rwb, off_t startblock,
size_t nblocks, FAR uint8_t *rdbuffer)
{
int ret = OK;
size_t readblocks = 0;
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, we
* directly copy write buffer to read buffer. This boost performance.
*/
if (rwb->wrmaxblocks > 0)
{
ret = nxsem_wait(&rwb->wrsem);
if (ret < 0)
{
return ret;
}
/* If the write buffer overlaps the block(s) requested */
if (rwb_overlap(rwb->wrblockstart, rwb->wrnblocks, startblock,
nblocks))
{
size_t rdblocks = 0;
size_t wrnpass = 0;
if (rwb->wrblockstart > startblock)
{
rdblocks = rwb->wrblockstart - startblock;
ret = rwb_read_(rwb, startblock, rdblocks, rdbuffer);
if (ret < 0)
{
rwb_semgive(&rwb->wrsem);
return ret;
}
startblock += ret;
nblocks -= ret;
rdbuffer += ret * rwb->blocksize;
readblocks += ret;
}
if (rwb->wrblockstart < startblock)
{
wrnpass = startblock - rwb->wrblockstart;
}
rdblocks = nblocks > (rwb->wrnblocks - wrnpass) ?
(rwb->wrnblocks - wrnpass) : nblocks;
memcpy(rdbuffer, &rwb->wrbuffer[wrnpass * rwb->blocksize],
rdblocks * rwb->blocksize);
startblock += rdblocks;
nblocks -= rdblocks;
rdbuffer += rdblocks * rwb->blocksize;
readblocks += rdblocks;
}
rwb_semgive(&rwb->wrsem);
}
#endif
ret = rwb_read_(rwb, startblock, nblocks, rdbuffer);
if (ret < 0)
{
return ret;
}
return readblocks + 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.
*/
ret = nxsem_wait(&rwb->rhsem);
if (ret < 0)
{
return ret;
}
if (rwb_overlap(rwb->rhblockstart, rwb->rhnblocks, startblock,
nblocks))
{
#ifdef CONFIG_DRVR_INVALIDATE
/* Just invalidate the read buffer startblock + nblocks data */
ret = rwb_invalidate_readahead(rwb, startblock, nblocks);
if (ret < 0)
{
ferr("ERROR: rwb_invalidate_readahead failed: %d\n", ret);
rwb_semgive(&rwb->rhsem);
return ret;
}
#else
rwb_resetrhbuffer(rwb);
#endif
}
rwb_semgive(&rwb->rhsem);
}
#endif
#ifdef CONFIG_DRVR_WRITEBUFFER
if (rwb->wrmaxblocks > 0)
{
finfo("startblock=%d wrbuffer=%p\n", startblock, wrbuffer);
ret = nxsem_wait(&rwb->wrsem);
if (ret < 0)
{
return ret;
}
ret = rwb_writebuffer(rwb, startblock, nblocks, wrbuffer);
rwb_semgive(&rwb->wrsem);
/* 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
#endif /* CONFIG_DRVR_WRITEBUFFER */
{
/* No write buffer.. just pass the write operation through via the
* flush callback.
*/
ret = rwb->wrflush(rwb->dev, wrbuffer, startblock, nblocks);
}
return 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)
{
ret = rwb_semtake(&rwb->wrsem);
if (ret < 0)
{
return ret;
}
rwb_resetwrbuffer(rwb);
rwb_semgive(&rwb->wrsem);
}
#endif
#ifdef CONFIG_DRVR_READAHEAD
if (rwb->rhmaxblocks > 0)
{
ret = rwb_semtake(&rwb->rhsem);
if (ret < 0)
{
return ret;
}
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
/****************************************************************************
* Name: rwb_flush
*
* Description:
* Flush the write buffer
*
****************************************************************************/
#ifdef CONFIG_DRVR_WRITEBUFFER
int rwb_flush(FAR struct rwbuffer_s *rwb)
{
int ret;
ret = rwb_forcetake(&rwb->wrsem);
rwb_wrcanceltimeout(rwb);
rwb_wrflush(rwb);
rwb_semgive(&rwb->wrsem);
return ret;
}
#endif
#endif /* CONFIG_DRVR_WRITEBUFFER || CONFIG_DRVR_READAHEAD */
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