mirror of
https://github.com/eclipse-threadx/filex.git
synced 2026-09-14 03:57:29 +08:00
Frédéric Desbiens
61b0b06c3e
* Updated version number constants * Updated copyright headers and removed revision history
156 lines
7.0 KiB
C
156 lines
7.0 KiB
C
/***************************************************************************
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* Copyright (c) 2024 Microsoft Corporation
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* Copyright (c) 2026-present Eclipse ThreadX contributors
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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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/** File */
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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_directory.h"
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#include "fx_file.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_file_extended_relative_seek 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 positions the internal file pointers to the specified */
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/* byte relative offset such that the next read or write operation is */
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/* performed there. */
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/* */
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/* INPUT */
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/* */
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/* file_ptr File control block pointer */
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/* byte_offset Byte offset of the seek */
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/* seek_from Direction for relative seek, */
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/* legal values are: */
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/* */
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/* FX_SEEK_BEGIN */
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/* FX_SEEK_END */
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/* FX_SEEK_FORWARD */
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/* FX_SEEK_BACK */
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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_file_extended_seek Seek to specified position */
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/* */
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/* CALLED BY */
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/* */
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/* Application Code */
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/* */
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/**************************************************************************/
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UINT _fx_file_extended_relative_seek(FX_FILE *file_ptr, ULONG64 byte_offset, UINT seek_from)
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{
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#ifndef FX_MEDIA_STATISTICS_DISABLE
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FX_MEDIA *media_ptr;
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/* First, determine if the file is still open. */
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if (file_ptr -> fx_file_id != FX_FILE_ID)
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{
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/* Return the file not open error status. */
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return(FX_NOT_OPEN);
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}
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/* Setup pointer to media structure. */
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media_ptr = file_ptr -> fx_file_media_ptr;
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/* Increment the number of times this service has been called. */
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media_ptr -> fx_media_file_relative_seeks++;
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#endif
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/* If trace is enabled, insert this event into the trace buffer. */
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FX_TRACE_IN_LINE_INSERT(FX_TRACE_FILE_RELATIVE_SEEK, file_ptr, byte_offset, seek_from, file_ptr -> fx_file_current_file_offset, FX_TRACE_FILE_EVENTS, 0, 0)
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/* Determine if seeking from the beginning is requested. */
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if (seek_from == FX_SEEK_BEGIN)
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{
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/* Yes, use the base file seek routine to seek from the beginning of
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the file. */
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return(_fx_file_extended_seek(file_ptr, byte_offset));
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}
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/* Otherwise, determine if seeking from the end is requested. */
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else if (seek_from == FX_SEEK_END)
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{
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/* Yes, seek from the end of the file. */
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/* Determine if the requested seek offset is greater than
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the file size. */
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if (byte_offset >= file_ptr -> fx_file_current_file_size)
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{
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/* Yes, just seek to the beginning of the file. */
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return(_fx_file_extended_seek(file_ptr, ((ULONG64) 0)));
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}
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else
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{
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/* Logically seek from the end of the file. */
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return(_fx_file_extended_seek(file_ptr, file_ptr -> fx_file_current_file_size - byte_offset));
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}
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}
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/* Otherwise, determine if seeking from the current position is requested. */
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else if (seek_from == FX_SEEK_FORWARD)
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{
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/* Yes, just seek ahead from the current file position. */
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return(_fx_file_extended_seek(file_ptr, file_ptr -> fx_file_current_file_offset + byte_offset));
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}
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/* Otherwise, seeking backward from the current position is assumed. */
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else
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{
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/* Determine if the backward offset is greater than the current file offset. */
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if (byte_offset >= file_ptr -> fx_file_current_file_offset)
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{
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/* Yes, just position the file to the beginning. */
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return(_fx_file_extended_seek(file_ptr, ((ULONG64) 0)));
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}
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else
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{
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/* Seek backward relative to the current position. */
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return(_fx_file_extended_seek(file_ptr, file_ptr -> fx_file_current_file_offset - byte_offset));
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}
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}
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}
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