int
_fat_block_zero(
rtems_filesystem_mount_table_entry_t *mt_entry,
uint32_t start,
uint32_t offset,
uint32_t count)
{
int rc = RC_OK;
fat_fs_info_t *fs_info = mt_entry->fs_info;
uint32_t blk = start;
uint32_t ofs = offset;
rtems_bdbuf_buffer *block = NULL;
uint32_t c = 0;
while(count > 0)
{
c = MIN(count, (fs_info->vol.bps - ofs));
if (c == fs_info->vol.bps)
rc = fat_buf_access(fs_info, blk, FAT_OP_TYPE_GET, &block);
else
rc = fat_buf_access(fs_info, blk, FAT_OP_TYPE_READ, &block);
if (rc != RC_OK)
return -1;
memset((block->buffer + ofs), 0, c);
fat_buf_mark_modified(fs_info);
count -= c;
blk++;
ofs = 0;
}
return 0;
}
/* _fat_block_read --
* This function reads 'count' bytes from device filesystem is mounted on,
* starts at 'start+offset' position where 'start' computed in sectors
* and 'offset' is offset inside sector (reading may cross sectors
* boundary; in this case assumed we want to read sequential sector(s))
*
* PARAMETERS:
* mt_entry - mount table entry
* start - sector num to start read from
* offset - offset inside sector 'start'
* count - count of bytes to read
* buff - buffer provided by user
*
* RETURNS:
* bytes read on success, or -1 if error occured
* and errno set appropriately
*/
ssize_t
_fat_block_read(
rtems_filesystem_mount_table_entry_t *mt_entry,
uint32_t start,
uint32_t offset,
uint32_t count,
void *buff
)
{
int rc = RC_OK;
register fat_fs_info_t *fs_info = mt_entry->fs_info;
ssize_t cmpltd = 0;
uint32_t blk = start;
uint32_t ofs = offset;
bdbuf_buffer *block = NULL;
uint32_t c = 0;
while (count > 0)
{
rc = fat_buf_access(fs_info, blk, FAT_OP_TYPE_READ, &block);
if (rc != RC_OK)
return -1;
c = MIN(count, (fs_info->vol.bps - ofs));
memcpy((buff + cmpltd), (block->buffer + ofs), c);
count -= c;
cmpltd += c;
blk++;
ofs = 0;
}
return cmpltd;
}
/* _fat_block_write --
* This function write 'count' bytes to device filesystem is mounted on,
* starts at 'start+offset' position where 'start' computed in sectors
* and 'offset' is offset inside sector (writing may cross sectors
* boundary; in this case assumed we want to write sequential sector(s))
*
* PARAMETERS:
* mt_entry - mount table entry
* start - sector num to start read from
* offset - offset inside sector 'start'
* count - count of bytes to write
* buff - buffer provided by user
*
* RETURNS:
* bytes written on success, or -1 if error occured
* and errno set appropriately
*/
ssize_t
_fat_block_write(
rtems_filesystem_mount_table_entry_t *mt_entry,
uint32_t start,
uint32_t offset,
uint32_t count,
const void *buff)
{
int rc = RC_OK;
fat_fs_info_t *fs_info = mt_entry->fs_info;
ssize_t cmpltd = 0;
uint32_t blk = start;
uint32_t ofs = offset;
bdbuf_buffer *block = NULL;
uint32_t c = 0;
while(count > 0)
{
c = MIN(count, (fs_info->vol.bps - ofs));
if (c == fs_info->vol.bps)
rc = fat_buf_access(fs_info, blk, FAT_OP_TYPE_GET, &block);
else
rc = fat_buf_access(fs_info, blk, FAT_OP_TYPE_READ, &block);
if (rc != RC_OK)
return -1;
memcpy((block->buffer + ofs), (buff + cmpltd), c);
fat_buf_mark_modified(fs_info);
count -= c;
cmpltd +=c;
blk++;
ofs = 0;
}
return cmpltd;
}
