/*FUNCTION*-------------------------------------------------------------------
*
* Function Name : MFS_Read_data_sector
* Returned Value : error_code
* Comments :
* Readsone sector into the DATA_SECTOR buffer
*END*---------------------------------------------------------------------*/
_mfs_error MFS_Read_data_sector
(
MFS_DRIVE_STRUCT_PTR drive_ptr,
MFS_HANDLE_PTR handle, /*[IN] handle of the file for which we are doing the read/write */
uint_32 sector_number, /*[IN] sector number to read/write from/to file system medium */
boolean hw_read /*[IN] if read of a sector is needed or just validation of a new one */
)
{
_mfs_error error;
error = MFS_NO_ERROR;
if ( sector_number != drive_ptr->DATA_SECTOR_NUMBER )
{
MFS_Flush_data_sector_buffer(drive_ptr);
MFS_Invalidate_data_sector(drive_ptr);
if (hw_read)
{
error = MFS_Read_device_sector(drive_ptr,sector_number,drive_ptr->DATA_SECTOR_PTR);
}
else
{
error = MFS_NO_ERROR;
}
if ( error == MFS_NO_ERROR )
{
drive_ptr->DATA_SECTOR_NUMBER = sector_number;
}
}
return(error);
}
_mfs_error MFS_Release_chain
(
MFS_DRIVE_STRUCT_PTR drive_ptr, /*[IN] the drive on which to operate */
uint_32 cluster_number /*[IN] first cluster number to release */
)
{
uint_32 next_cluster,first_sector_in_cluster,last_sector_in_cluster;
_mfs_error error_code;
#if MFSCFG_READ_ONLY_CHECK
if (MFS_is_read_only (NULL, drive_ptr))
{
return MFS_DISK_IS_WRITE_PROTECTED;
}
#endif
if ( (cluster_number >= CLUSTER_MIN_GOOD) && (cluster_number <= drive_ptr->LAST_CLUSTER) )
{
do
{
error_code = MFS_get_cluster_from_fat(drive_ptr,cluster_number,&next_cluster);
if ( error_code != MFS_NO_ERROR )
{
break;
}
else if ( ((next_cluster > drive_ptr->LAST_CLUSTER) || (next_cluster < CLUSTER_MIN_GOOD)) && (next_cluster != CLUSTER_EOF) )
{
error_code = MFS_LOST_CHAIN;
break;
}
first_sector_in_cluster = CLUSTER_TO_SECTOR(cluster_number);
last_sector_in_cluster = first_sector_in_cluster+ drive_ptr->BPB.SECTORS_PER_CLUSTER -1;
// Check to see if the currently cached data sector is being deleted.
if ( (drive_ptr->DATA_SECTOR_NUMBER >= first_sector_in_cluster) && (drive_ptr->DATA_SECTOR_NUMBER <= last_sector_in_cluster) )
{
error_code = MFS_Invalidate_data_sector(drive_ptr);
if ( error_code != MFS_NO_ERROR )
{
return error_code;
}
}
error_code = MFS_Put_fat(drive_ptr,cluster_number, CLUSTER_UNUSED);
if ( error_code )
{
break;
}
cluster_number = next_cluster;
} while ( cluster_number != CLUSTER_EOF );
error_code = MFS_Write_back_fat(drive_ptr);
}
else
{
error_code = MFS_NO_ERROR;
}
return(error_code);
}
