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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** FileX Component */
/** */
/** Utility */
/** */
/**************************************************************************/
/**************************************************************************/
#define FX_SOURCE_CODE
/* Include necessary system files. */
#include "fx_api.h"
#ifdef FX_ENABLE_EXFAT
#include "fx_directory_exFAT.h"
#include "fx_utility.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _fx_utility_exFAT_cluster_free PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function deallocates clusters deleted unknown type */
/* directory entry. */
/* */
/* INPUT */
/* */
/* media_ptr Media control block pointer */
/* work_ptr Pointer to directory to */
/* unknown directory entry */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* _fx_utility_32_unsigned_read Read 32-bit value */
/* _fx_utility_64_unsigned_read Read 64-bit value */
/* _fx_utility_FAT_entry_read Read FAT entry */
/* _fx_utility_FAT_entry_write Write FAT entry */
/* _fx_utility_exFAT_cluster_state_set Set cluster state */
/* */
/* CALLED BY */
/* */
/* _fx_directory_exFAT_unicode_entry_write */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 William E. Lamie Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _fx_utility_exFAT_cluster_free(FX_MEDIA *media_ptr, UCHAR *work_ptr)
{
ULONG cluster;
ULONG64 data_length;
ULONG clusters_released;
ULONG clusters_count;
ULONG bytes_per_cluster;
ULONG contents = 0;
UCHAR dont_use_fat;
UINT status;
/* Pickup the cluster to release. */
cluster = _fx_utility_32_unsigned_read(&(work_ptr[FX_EXFAT_FIRST_CLUSTER]));
/* Pickup the data length. */
data_length = _fx_utility_64_unsigned_read(&(work_ptr[FX_EXFAT_DATA_LENGTH]));
/* Pickup the flag that determines if the FAT should be used. */
dont_use_fat = (work_ptr[FX_EXFAT_SECOND_FLAG] >> 1) & 1;
/* Default status to success. */
status = FX_SUCCESS;
/* Is the allocation possible flag cleared? Is there any allocated cluster for this entry? */
if (((work_ptr[FX_EXFAT_SECOND_FLAG] & FX_EXFAT_SECOND_FLAG_ALLOCATION_POSSIBLE_MASK) == 0) ||
(cluster == 0) ||
(data_length == 0))
{
/* No cluster allocated to this entry, nothing to deallocate. */
return(FX_SUCCESS);
}
/* Calculate the number of bytes per cluster. */
bytes_per_cluster = ((ULONG)media_ptr -> fx_media_bytes_per_sector) *
((ULONG)media_ptr -> fx_media_sectors_per_cluster);
/* Determine how many clusters. */
clusters_count = (ULONG)((data_length + bytes_per_cluster - 1) / bytes_per_cluster - 1);
/* Initialize released cluster count to 0. */
clusters_released = 0;
/* Follow the link of FAT entries. */
while ((cluster >= FX_FAT_ENTRY_START) && (cluster < FX_RESERVED_1_exFAT))
{
/* Increment the number of clusters released. */
clusters_released++;
/* Determine if the FAT chain is to be used. */
if (dont_use_fat)
{
/* Yes, don't use the FAT chain. */
/* Check for file size range. */
if (clusters_released - 1 >= clusters_count)
{
/* Set the next cluster to LAST to indicate it is the last cluster. */
contents = FX_LAST_CLUSTER_exFAT;
}
else
{
/* The next cluster is just after the current cluster. */
contents = cluster + 1;
}
}
else
{
/* Read the current cluster entry from the FAT. */
status = _fx_utility_FAT_entry_read(media_ptr, cluster, &contents);
/* Check the return value. */
if (status != FX_SUCCESS)
{
/* Return the error status. */
return(status);
}
}
/* Check for data corruption. */
if ((cluster == contents) || (clusters_released > media_ptr -> fx_media_total_clusters))
{
/* Return the bad status. */
return(FX_FAT_READ_ERROR);
}
/* Make the current cluster available. */
if (!dont_use_fat)
{
/* Write the FAT to free the cluster. */
status = _fx_utility_FAT_entry_write(media_ptr, cluster, FX_FREE_CLUSTER);
/* Check the return value. */
if (status != FX_SUCCESS)
{
/* Return the error status. */
return(status);
}
}
/* Set cluster state in the bitmap. */
status = _fx_utility_exFAT_cluster_state_set(media_ptr, cluster, FX_EXFAT_BITMAP_CLUSTER_FREE);
/* Check the return status. */
if (status != FX_SUCCESS)
{
/* Return the bad status. */
return(status);
}
/* Setup for the next cluster. */
cluster = contents;
}
/* Update the free clusters in the media control block. */
media_ptr -> fx_media_available_clusters = media_ptr -> fx_media_available_clusters + clusters_released;
/* Return success. */
return(FX_SUCCESS);
}
#endif /* FX_ENABLE_EXFAT */
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