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/*********************************************************************************
Function:
void FSGetDiskProperties(FS_DISK_PROPERTIES* properties)
Summary:
Allows user to get the disk properties (size of disk, free space, etc)
Conditions:
1) ALLOW_GET_DISK_PROPERTIES must be defined in FSconfig.h
2) a FS_DISK_PROPERTIES object must be created before the function is called
3) the new_request member of the FS_DISK_PROPERTIES object must be set before
calling the function for the first time. This will start a new search.
4) this function should not be called while there is a file open. Close all
files before calling this function.
Input:
properties - a pointer to a FS_DISK_PROPERTIES object where the results should
be stored.
Return Values:
This function returns void. The properties_status of the previous call of this
function is located in the properties.status field. This field has the
following possible values:
FS_GET_PROPERTIES_NO_ERRORS - operation completed without error. Results
are in the properties object passed into the function.
FS_GET_PROPERTIES_DISK_NOT_MOUNTED - there is no mounted disk. Results in
properties object is not valid
FS_GET_PROPERTIES_CLUSTER_FAILURE - there was a failure trying to read a
cluster from the drive. The results in the properties object is a partial
result up until the point of the failure.
FS_GET_PROPERTIES_STILL_WORKING - the search for free sectors is still in
process. Continue calling this function with the same properties pointer
until either the function completes or until the partial results meets the
application needs. The properties object contains the partial results of
the search and can be used by the application.
Side Effects:
Can cause errors if called when files are open. Close all files before
calling this function.
Calling this function without setting the new_request member on the first
call can result in undefined behavior and results.
Calling this function after a result is returned other than
FS_GET_PROPERTIES_STILL_WORKING can result in undefined behavior and results.
Description:
This function returns the information about the mounted drive. The results
member of the properties object passed into the function is populated with
the information about the drive.
Before starting a new request, the new_request member of the properties
input parameter should be set to TRUE. This will initiate a new search
request.
This function will return before the search is complete with partial results.
All of the results except the free_clusters will be correct after the first
call. The free_clusters will contain the number of free clusters found up
until that point, thus the free_clusters result will continue to grow until
the entire drive is searched. If an application only needs to know that a
certain number of bytes is available and doesn't need to know the total free
size, then this function can be called until the required free size is
verified. To continue a search, pass a pointer to the same FS_DISK_PROPERTIES
object that was passed in to create the search.
A new search request sould be made once this function has returned a value
other than FS_GET_PROPERTIES_STILL_WORKING. Continuing a completed search
can result in undefined behavior or results.
Typical Usage:
<code>
FS_DISK_PROPERTIES disk_properties;
disk_properties.new_request = TRUE;
do
{
my_results = FSGetDiskProperties(&disk_properties);
} while (disk_properties->properties_status == FS_GET_PROPERTIES_STILL_WORKING);
</code>
results.disk_format - contains the format of the drive. Valid results are
FAT12(1), FAT16(2), or FAT32(3).
results.sector_size - the sector size of the mounted drive. Valid values are
512, 1024, 2048, and 4096.
results.sectors_per_cluster - the number sectors per cluster.
results.total_clusters - the number of total clusters on the drive. This
can be used to calculate the total disk size (total_clusters *
sectors_per_cluster * sector_size = total size of drive in bytes)
results.free_clusters - the number of free (unallocated) clusters on the drive.
This can be used to calculate the total free disk size (free_clusters *
sectors_per_cluster * sector_size = total size of drive in bytes)
Remarks:
PIC24F size estimates:
Flash - 400 bytes (-Os setting)
PIC24F speed estimates:
Search takes approximately 7 seconds per Gigabyte of drive space. Speed
will vary based on the number of sectors per cluster and the sector size.
*********************************************************************************/ |
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