int 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) {
fvdbg("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
#endif
{
/* No write buffer.. just pass the write operation through via the
* flush callback.
*/
ret = rwb->wrflush(rwb->dev, wrbuffer, startblock, nblocks);
}
return ret;
}
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;
}
int rwb_mediaremoved(FAR struct rwbuffer_s *rwb)
{
#ifdef CONFIG_FS_WRITEBUFFER
rwb_semtake(&rwb->wrsem);
rwb_resetwrbuffer(rwb);
rwb_semgive(&rwb->wrsem);
#endif
#ifdef CONFIG_FS_READAHEAD
rwb_semtake(&rwb->rhsem);
rwb_resetrhbuffer(rwb);
rwb_semgive(&rwb->rhsem);
#endif
return 0;
}
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;
}
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)
{
fvdbg("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)
{
fdbg("Write buffer kmm_malloc(%d) failed\n", allocsize);
return -ENOMEM;
}
}
fvdbg("Write buffer size: %d bytes\n", allocsize);
}
#endif /* CONFIG_DRVR_WRITEBUFFER */
#ifdef CONFIG_DRVR_READAHEAD
if (rhmaxblocks > 0)
{
fvdbg("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)
{
fdbg("Read-ahead buffer kmm_malloc(%d) failed\n", allocsize);
return -ENOMEM;
}
}
fvdbg("Read-ahead buffer size: %d bytes\n", allocsize);
}
#endif /* CONFIG_DRVR_READAHEAD */
return OK;
}