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Transition FileX to Eclipse Fundation

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TiejunZhou
2024-01-02 07:35:14 +00:00
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common/src/fx_utility_FAT_sector_get.c
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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"
#include "fx_utility.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _fx_utility_FAT_sector_get PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function gets the sector of supplied FAT entry. */
/* */
/* INPUT */
/* */
/* media_ptr Media control block pointer */
/* cluster Cluster entry number */
/* */
/* OUTPUT */
/* */
/* return sector of FAT entry */
/* */
/* CALLS */
/* */
/* */
/* 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 */
/* */
/**************************************************************************/
ULONG _fx_utility_FAT_sector_get(FX_MEDIA *media_ptr, ULONG cluster)
{
ULONG FAT_sector;
ULONG byte_offset;
/* Determine which type of FAT is present. */
if (media_ptr -> fx_media_12_bit_FAT)
{
/* 12-bit FAT is present. */
/* Calculate the byte offset to the cluster entry. */
byte_offset = (((ULONG)cluster << 1) + cluster) >> 1;
}
else if (!media_ptr -> fx_media_32_bit_FAT)
{
/* 16-bit FAT is present. */
/* Calculate the byte offset to the cluster entry. */
byte_offset = (((ULONG)cluster) << 1);
}
else
{
/* 32-bit FAT is present. */
/* Calculate the byte offset to the cluster entry. */
byte_offset = (((ULONG)cluster) * 4);
}
/* Calculate the FAT sector the requested FAT entry resides in. */
FAT_sector = (byte_offset / media_ptr -> fx_media_bytes_per_sector) +
(ULONG)media_ptr -> fx_media_reserved_sectors;
/* Return successful status. */
return(FAT_sector);
}