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;
}
int rwb_read(FAR struct rwbuffer_s *rwb, off_t startblock, uint32_t nblocks,
FAR uint8_t *rdbuffer)
{
uint32_t remaining;
fvdbg("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 (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 startblock = startblock;
size_t nbufblocks = 0;
off_t bufferend;
/* Loop for each block we find in the read-head buffer. Count
* the number of buffers that we can read from read-ahead
* buffer.
*/
bufferend = rwb->rhblockstart + rwb->rhnblocks;
while ((startblock >= rwb->rhblockstart) &&
(startblock < bufferend) &&
(remaining > 0))
{
/* This is one more that we will read from the read ahead
* buffer.
*/
nbufblocks++;
/* And one less that we will read from the media */
startblock++;
remaining--;
}
/* Then read the data from the read-ahead buffer */
rwb_bufferread(rwb, startblock, nbufblocks, &rdbuffer);
}
/* 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)
{
int ret = rwb_rhreload(rwb, startblock);
if (ret < 0)
{
fdbg("ERROR: Failed to fill the read-ahead buffer: %d\n", ret);
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
#else
{
/* No read-ahead buffering, (re)load the data directly into
* the user buffer.
*/
ret = rwb->rhreload(rwb->dev, startblock, nblocks, rdbuffer);
}
#endif
return ret;
}
