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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_system.h"
#include "fx_media.h"
#include "fx_utility.h"
#include "fx_directory_exFAT.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _fx_utility_exFAT_bitmap_start_sector_get PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function gets the start sector of exFAT bitmap. */
/* */
/* INPUT */
/* */
/* media_ptr Media control block pointer */
/* bitmap_started_sector Pointer to ULONG */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* _fx_utility_logical_sector_read Read logical sector */
/* _fx_utility_64_unsigned_read Read a ULONG64 from memory */
/* */
/* CALLED BY */
/* */
/* FileX System Functions */
/* */
/* 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_bitmap_start_sector_get(FX_MEDIA *media_ptr, ULONG *bitmap_started_sector)
{
ULONG sectors_count;
UCHAR *dir_entry_ptr;
/* Initialize the sector count. */
sectors_count = 0;
/* Go through the first cluster of exFAT root directory. This cluster should
contain BitMap allocation DirEntry */
while (sectors_count < media_ptr -> fx_media_sectors_per_cluster)
{
/* Will use read sector function with cache functionality since first cluster
will be used by other services. */
if (FX_SUCCESS != _fx_utility_logical_sector_read(media_ptr,
(ULONG64) (media_ptr -> fx_media_root_sector_start + sectors_count),
media_ptr -> fx_media_memory_buffer,
((ULONG) 1), FX_DATA_SECTOR))
{
/* Error reading the sector, get out of the loop. */
break;
}
/* Increment the sectors count. */
sectors_count++;
/* Setup pointer to directory entry. */
dir_entry_ptr = media_ptr -> fx_media_memory_buffer;
/* Go through the read buffer and try to find BitMap table directory entry. */
while (dir_entry_ptr < (media_ptr -> fx_media_memory_buffer +
media_ptr -> fx_media_bytes_per_sector))
{
/* Determine if this entry is the bitmap allocation type. */
if (FX_EXFAT_DIR_ENTRY_TYPE_ALLOCATION_BITMAP == dir_entry_ptr[FX_EXFAT_ENTRY_TYPE])
{
/* Yes, calculate BitMap table start sector. */
*bitmap_started_sector = media_ptr -> fx_media_data_sector_start +
(UINT)((dir_entry_ptr[FX_EXFAT_FIRST_CLUSTER] - FX_FAT_ENTRY_START) <<
media_ptr -> fx_media_exfat_sector_per_clusters_shift);
/* Check FirstCluster and DataLength fields for error. */
if ((0 == *bitmap_started_sector) ||
(media_ptr -> fx_media_total_clusters >
((ULONG)_fx_utility_64_unsigned_read(&dir_entry_ptr[FX_EXFAT_DATA_LENGTH]) <<
BITS_PER_BYTE_SHIFT)))
{
/* Media invalid - return error! */
return(FX_MEDIA_INVALID);
}
/* Return success! */
return(FX_SUCCESS);
}
else
{
/* Move to next directory entry. */
dir_entry_ptr += FX_EXFAT_DIR_ENTRY_SIZE;
}
}
}
/* Return media invalid error. */
return(FX_MEDIA_INVALID);
}
#endif /* FX_ENABLE_EXFAT */
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