FAT32 文件系统C语言接口.docx

FAT32 文件系统C语言接口.docx

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FAT32文件系统C语言接口

FATFileSystemModule

FatFsmoduleisanexperimentalprojecttoimplementaFATfilesystemtosmallembddedsystems.TheFatFsmoduleiswrittenincompliancewithANSIC,thereforeitisindependentofhardwarearchitecture.Itcanbeincorporatedintomost8-bitmicrocontrollers,suchas8051,PIC,AVR,H8,Z80andetc...,withoutanychange.Icreatedtwomodulesindifferentconfigurationsinconsiderationofvarioususe.

FeaturesofFatFsModule

1.SeparatedbufferforFATstructureandeachfile,suitableforfastmultiplefileaccsess.

2.Supportsmultipledrives/partitions.

3.SupportsFAT12,FAT16（+FAT64）andFAT32.（FAT64:

FAT16in64KB/cluster）

4.Supports8.3formatfilenameandNTlowercaseflag.（LFNisnotsupported）

5.Supportstwopartitioningrules:

FDISKandSuper-floppy.

6.Optimizedfor8/16-bitmicrocontrollers.

FeaturesofTiny-FatFsModule（differenttoFatFs）

1.Verylowmemoryconsumption,suitableforsmallmemorysystem.（RAM:

1KB）

2.Supportsonlysingledrive.

ApplicationInterface

FatFs/Tiny-FatFsmoduleprovidesfollowingfunctions.

∙f_mount-Register/UnregisteraWorkArea

∙f_open-Open/CreateaFile

∙f_close-CloseaFile

∙f_read-ReadFile

∙f_write-WriteFile

∙f_lseek-MoveR/WPointer

∙f_sync-FlushCachedData

∙f_opendir-OpenaDirectory

∙f_readdir-ReadaDirectoryItem

∙f_getfree-GetFreeClusters

∙f_stat-GetFileStatus

∙f_mkdir-CreateaDirectory

∙f_unlink-RemoveaFileorDirectory

∙f_chmod-ChangeAttribute

∙f_rename-Rename/MoveaFileorDirectory

∙f_mkfs-CreateaFileSystemontheDrive

f_mount

Thef_mountfucntionregisters/unregistersaworkareatotheFatFsmodule.

FRESULTf_mount（

BYTEDrive,/*Logicaldrivenumber*/

FATFS*FileSystemObject/*Pointertotheworkarea*/

）;

Parameters

Drive

Logicaldrivenumber（0-9）toregister/unregistertheworkarea.Always0forTiny-FatFs.

FileSystemObject

Pointertotheworkarea（filesystemobject）toberegistered.

ReturnValues

FR_OK（0）

Thefunctionsucceeded.

FR_INVALID_DRIVE

Thedrivenumberisinvalid.

Description

Thef_mountfunctionregisters/unregistersaworkareatotheFatFsmodule.Theworkareamustbegiventothelogicaldrivewiththisfunctionbeforeusinganyfilefunction.Tounregisteraworkarea,specifyaNULLtotheFileSystemObject,andthentheworkareacanbediscarded.

Thisfunctiononlyinitializestheworkareaandregistersitsaddresstotheinternaltable,anyaccesstothediskI/Olayerdoesnotoccure.Actualmountingprocessisperformedinanyotherfilefuncitonswithpathnamewhenitisneeded.

References

FATFS

Return

f_open

Thef_openfunctioncreatesafileobjecttobeusedtoaccessthefile.

FRESULTf_open（

FIL*FileObject,/*Pointertotheblankfileobjectstructure*/

constchar*FileName,/*Pointertothefileneme*/

BYTEModeFlags/*Modeflags*/

）;

Parameters

FileObject

Pointertothefileobjectstructuretobecreated.Afterthef_openfuncitonsucceeded,thefilecanbeaccessedwiththefileobjectstructureuntilitisclosed.

FileName

Pointertoanull-terminatedstringthatspecifiesthefilenametocreateoropen.

ModeFlags

Specifiesthetypeofaccessandopenmethodforthefile.Itisspecifiedbyacombinationoffollowingflags.

Value

Description

FA_READ

Specifiesreadaccesstotheobject.Datacanbereadfromthefile.

CombinewithFA_WRITEforread-writeaccess.

FA_WRITE

Specifieswriteaccesstotheobject.Datacanbewrittentothefile.

CombinewithFA_READforread-writeaccess.

FA_OPEN_EXISTING

Opensthefile.Thefunctionfailsifthefileisnotexisting.

FA_OPEN_ALWAYS

Opensthefile,ifitisexisting.Ifnot,thefunctioncreatesthenewfile.

FA_CREATE_NEW

Createsanewfile.Thefunctionfailsifthefileisalreadyexisting.

FA_CREATE_ALWAYS

Createsanewfile.Ifthefileisexisting,itistruncatedandoverwritten.

ReturnValues

FR_OK（0）

Thefunctionsucceededandthefileobjectisvalid.

FR_NO_FILE

Couldnotfindthefile.

FR_NO_PATH

Couldnotfindthepath.

FR_INVALID_NAME

Thefilenameisinvalid.

FR_INVALID_DRIVE

Thedrivenumberisinvalid.

FR_EXIST

Thefileisalreadyexisting.

FR_DENIED

Therequiredaccesswasdeniedduetoanyoffollowingreasons:

writemodeopenofafilethathasread-onlyattribute,filecreationunderexistingasamenamedirectoryorread-onlyfile,cannotbecreatedduetothedirectorytableordiskfull.

FR_NOT_READY

Thediskdrivecannotworkduetonomediuminthedriveoranyotherreason.

FR_WRITE_PROTECTED

Writemodeopenorcreationunderthemediumiswriteprotected.

FR_RW_ERROR

Thefunctionfailedduetoadiskerrororaninternalerror.

FR_NOT_ENABLED

Thelogicaldrivehasnoworkarea.

FR_NO_FILESYSTEM

ThereisnovalidFATpartitiononthedisk.

Description

Thecreatedfileobjectisusedforsubsequentcallstorefertothefile.Whencloseanopenfileobject,usef_closefunction.

Beforeusinganyfilefunction,workarea（filesystemobject）mustbegiventoeachlogicaldrivewithf_mountfunction.Allfilefunctionscanworkafterthisprocedure.

Themodeflags,FA_WRITE,FA_CREATE_ALWAYS,FA_CREATE_NEW,FA_OPEN_ALWAYS,arenotsupportedinread-onlyconfiguration.

Example（FileCopy）

voidmain（）

{

FATFSfs;//Workarea（filesystemobject）forlogicaldrive

FILfsrc,fdst;//fileobjects

BYTEbuffer[4096];//filecopybuffer

FRESULTres;//FatFsfunctioncommonresultcode

WORDbr,bw;//FileR/Wcount

//Registeraworkareatologicaldrive0

f_mount（0,&fs）;

//Opensourcefile

res=f_open（&fsrc,"srcfile.dat",FA_OPEN_EXISTING|FA_READ）;

if（res）die（res）;

//Createdestinationfile

res=f_open（&fdst,"dstfile.dat",FA_CREATE_ALWAYS|FA_WRITE）;

if（res）die（res）;

//Copysourcetodestination

for（;;）{

res=f_read（&fsrc,buffer,sizeof（buffer）,&br）;

if（res||br==0）break;//errororeof

res=f_write（&fdst,buffer,br,&bw）;

if（res||bw

}

//Closeallfiles

f_close（&fsrc）;

f_close（&fdst）;

//Unregisteraworkareabeforediscardit

f_mount（0,NULL）;

}

References

f_read,f_write,f_close,FIL,FATFS

Return

f_close

Thef_closefunctionclosesanopenfile.

FRESULTf_close（

FIL*FileObject/*Pointertothefileobjectstructure*/

）;

Parameter

FileObject

Pointertotheopenfileobjectstructuretobeclosed.

ReturnValues

FR_OK（0）

Thefileobjecthasbeenclosedsuccessfuly.

FR_RW_ERROR

Thefunctionfailedduetoadiskerrororaninternalerror.

FR_NOT_READY

Thediskdrivecannotworkduetonomediuminthedriveoranyotherreason.

FR_INVALID_OBJECT

Thefileobjectisinvalid.

Description

Thef_closefunctionclosesanopenfileobject.Ifanydatahasbeenwrittentothefile,thecachedinformationofthefileiswrittenbacktothedisk.Afterthefunctionsucceeded,thefileobjectisnolongervalidanditcanbediscarded.Ifthefileobjecthasbeenopenedinread-onlymode,itmaybediscardedwithoutclosingprocessbythisfunction.

References

f_open,f_read,f_write,f_sync,FIL,FATFS

Return

f_read

Thef_readfunctionreadsdatafromafile.

FRESULTf_read（

FIL*FileObject,/*Pointertothefileobjectstructure*/

void*Buffer,/*Pointertothebuffertostorereaddata*/

WORDByteToRead,/*Numberofbytestoread*/

WORD*ByteRead/*Pointertothevariabletoreturnnumberofbytesread*/

）;

Parameters

FileObject

Pointertotheopenfileobject.

Buffer

Pointertothebuffertostorereaddata

ByteToRead

Numberofbytestoread

ByteRead

PointertotheWORDvariabletoreturnnumberofbytesread.

ReturnValues

FR_OK（0）

Thefunctionsucceeded.

FR_DENIED

Thefunctiondeniedduetothefilehasbeenopenedinwriteonlymode.

FR_RW_ERROR

Thefunctionfailedduetoadiskerrororaninternalerror.

FR_NOT_READY

Thediskdrivecannotworkduetonomediuminthedriveoranyotherreason.

FR_INVALID_OBJECT

Thefileobjectisinvalid.

Description

Thefilepointerinthefileobjectincreasesinnumberofbytesread.TheByteReadwillbecomelessthanByteToReadwhenthereadpointerreachedtoendofthefileoranyerroroccuredduringthereadoperation.

References

f_open,f_write,f_close,FIL

Return

f_write

Thef_writewritesdatatoafile.

FRESULTf_write（

FIL*FileObject,/*Pointertothefileobjectstructure*/

constvoid*Buffer,/*Pointertothedatatobewritten*/

WORDByteToWrite,/*Numberofbytestowrite*/

WORD*ByteWritten/*Pointertothevariabletoreturnnumberofbyteswritten*/

）;

Parameter

FileObject

Pointertotheopenfileobjectstructure.

Buffer

Pointertothedatatobewritten.

ByteToWrite

Specifiesnumberofbytestowrite.

ByteWritten

PointertotheWORDvariabletoreturnnumberofbyteswritten.

ReturnValues

FR_OK（0）

Thefunctionsucceeded.

FR_DENIED

Thefunctiondeniedduetothefilehasbeenopenedinreadonlymode.

FR_RW_ERROR

Thefunctionfailedduetoadiskerrororaninternalerror.

FR_NOT_READY

Thediskdrivecannotworkduetonomediuminthedriveoranyotherreason.

FR_INVALID_OBJECT

Thefileobjectisinvalid.

Description

Theread/writepointerinthefileobjectisincreasedinnumberofbyteswritten.TheByteWrittenwillbecomelessthanByteToWritewhendiskgetsfullduringwritefunction.Thisfunctionisnotsupportedinread-onlyconfiguration.

References

f_open,f_read,f_close,FIL

Return

f_lseek

Thef_lseekfunctionemovesthefileread/writepointerofanopenfileobject.

FRESULTf_lseek（

FIL*FileObject,/*Pointertothefileobjectstructure*

DWORDOffset/*File