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/*************************************************************************** |
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* Copyright (c) 2024 Microsoft Corporation |
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* |
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* This program and the accompanying materials are made available under the |
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* terms of the MIT License which is available at |
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* https://opensource.org/licenses/MIT. |
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* |
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* SPDX-License-Identifier: MIT |
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**************************************************************************/ |
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/**************************************************************************/ |
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/**************************************************************************/ |
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/** */ |
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/** FileX Component */ |
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/** */ |
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/** Utility */ |
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/** */ |
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/**************************************************************************/ |
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/**************************************************************************/ |
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#define FX_SOURCE_CODE |
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/* Include necessary system files. */ |
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#include "fx_api.h" |
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#include "fx_system.h" |
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#include "fx_utility.h" |
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/**************************************************************************/ |
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/* */ |
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/* FUNCTION RELEASE */ |
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/* */ |
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/* _fx_utility_FAT_map_flush PORTABLE C */ |
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/* 6.1 */ |
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/* AUTHOR */ |
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/* */ |
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/* William E. Lamie, Microsoft Corporation */ |
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/* */ |
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/* DESCRIPTION */ |
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/* */ |
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/* This function updates mirrors changes in the primary FAT to each of */ |
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/* secondary FATs in the media. */ |
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/* */ |
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/* INPUT */ |
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/* */ |
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/* media_ptr Media control block pointer */ |
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/* */ |
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/* OUTPUT */ |
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/* */ |
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/* return status */ |
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/* */ |
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/* CALLS */ |
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/* */ |
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/* _fx_utility_logical_sector_read Read FAT sector into memory */ |
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/* _fx_utility_logical_sector_write Write FAT sector back to disk */ |
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/* */ |
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/* CALLED BY */ |
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/* */ |
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/* FileX System Functions */ |
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/* */ |
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/* RELEASE HISTORY */ |
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/* */ |
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/* DATE NAME DESCRIPTION */ |
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/* */ |
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/* 05-19-2020 William E. Lamie Initial Version 6.0 */ |
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/* 09-30-2020 William E. Lamie Modified comment(s), */ |
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/* resulting in version 6.1 */ |
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/* */ |
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/**************************************************************************/ |
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340691 |
UINT _fx_utility_FAT_map_flush(FX_MEDIA *media_ptr) |
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{ |
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ULONG FAT_sector, last_sector; |
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UINT i, status, FATs; |
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UCHAR sectors_per_bit; |
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/* Determine how many FAT sectors each bit in the bit map represents. Depending on |
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the number of sectors in the primary FAT, each bit in this map may represent one |
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or more primary FAT sectors. Because of this, it is possible some FAT sectors that |
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were not changed may get flushed out to the secondary FAT. However, this method |
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provides very nice performance benefits during normal operation and is much more |
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reasonable than performing a total copy of the primary FAT to each secondary FAT |
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on media flush and media close. */ |
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✓✓ |
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if (media_ptr -> fx_media_sectors_per_FAT % (FX_FAT_MAP_SIZE << 3) == 0) |
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{ |
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sectors_per_bit = (UCHAR)(media_ptr -> fx_media_sectors_per_FAT / (FX_FAT_MAP_SIZE << 3)); |
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} |
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else |
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{ |
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sectors_per_bit = (UCHAR)(media_ptr -> fx_media_sectors_per_FAT / (FX_FAT_MAP_SIZE << 3) + 1); |
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} |
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/* Loop through the FAT update map to mirror primary FAT sectors to secondary FAT(s). */ |
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✓✓ |
3066195 |
for (i = 0; i < FX_FAT_MAP_SIZE << 3; i++) |
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{ |
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/* Determine if there are FAT changes specified by this entry. */ |
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✓✓ |
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if ((media_ptr -> fx_media_fat_secondary_update_map[i >> 3] & (1 << (i & 7))) == 0) |
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{ |
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/* No, look at the next bit map entry. */ |
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continue; |
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} |
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/* Setup the parameters for performing the update. */ |
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FAT_sector = i * sectors_per_bit + media_ptr -> fx_media_reserved_sectors; |
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last_sector = FAT_sector + sectors_per_bit; |
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/* Make sure the last update sector is within range. */ |
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✓✓ |
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if (last_sector > (media_ptr -> fx_media_sectors_per_FAT + media_ptr -> fx_media_reserved_sectors)) |
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{ |
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last_sector = media_ptr -> fx_media_sectors_per_FAT + media_ptr -> fx_media_reserved_sectors; |
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} |
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/* Loop to mirror primary FAT sectors to secondary FAT(s). */ |
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✓✓ |
3529382 |
for (; FAT_sector < last_sector; FAT_sector++) |
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{ |
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/* Read the FAT sector. */ |
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status = _fx_utility_logical_sector_read(media_ptr, (ULONG64) FAT_sector, |
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media_ptr -> fx_media_memory_buffer, ((ULONG) 1), FX_FAT_SECTOR); |
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/* Determine if an error occurred. */ |
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✓✓ |
3294086 |
if (status != FX_SUCCESS) |
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{ |
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/* Return the error status. */ |
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return(status); |
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} |
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/* Pickup how many secondary FATs there are. */ |
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FATs = media_ptr -> fx_media_number_of_FATs - 1; |
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/* Loop to update additional FAT entries. */ |
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✓✓ |
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while (FATs) |
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{ |
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/* Mirror main FAT sector write into the additional FATs. */ |
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status = _fx_utility_logical_sector_write(media_ptr, |
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((ULONG64) FAT_sector) + ((ULONG64)FATs * (ULONG64)(media_ptr -> fx_media_sectors_per_FAT)), |
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media_ptr -> fx_media_memory_buffer, ((ULONG) 1), FX_FAT_SECTOR); |
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/* Determine if an error occurred. */ |
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✓✓ |
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if (status != FX_SUCCESS) |
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{ |
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/* Return the error status. */ |
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return(status); |
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} |
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/* Decrement the number of FATs. */ |
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FATs--; |
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} |
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} |
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} |
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/* Clear the bit map that indicates primary FAT updates. */ |
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✓✓ |
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for (i = 0; i < FX_FAT_MAP_SIZE; i++) |
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{ |
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/* Clear each entry in the bit map. */ |
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media_ptr -> fx_media_fat_secondary_update_map[i] = 0; |
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} |
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/* Return a successful completion. */ |
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return(FX_SUCCESS); |
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} |
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