SD卡FAT16文件系统源代码.docx

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1、*@return-4filealreadyopenedforreading*FATLib.h:interfacefortheFATLib.*classFATLib:aportableFATdecoderclasswhichishardwareindependent.*Allhardwarespecificoperationsareabstractedwiththe*classHALayer.TheFATLibclassoperateswithonlythebuffer*whichitpassestotheclassHALayer**Author:IvanSham*Date:JUl

2、y1,2004*Version:2.0*Note:DevelopedforWilliamHueandPeteRizun*******************************************************************ChangeLog**Date

3、Author

4、Reasonforchange**Aug31/04WilliamHue*****Jul18/04AlexJiang******Jan02/05WilliamHue***/Changedchartypestounsignedchar.Putmoreparenthesesinabs()mac

5、ro.PortedtoFABbeltclip.Madelocalvariablesandfunctionsstaticandmovedtofatlib.c.Prefixedpublicfuntioswith"fat_".Variousbugfixesandclean-upforCircuitCellararticle.#ifndef_FATLIB_#define_FATLIB_#include"HALayer.h"#defineUNKNOWN0#defineFAT161#defineDIRECTORYTRUE#defineFILEFALSE*@return-4filealread

6、yopenedforreading#defineREADTRUE#defineWRITEFALSE#defineBUFFER_SIZE2#defineabs(x)(((x)>0)?(x):(-(x)))////memberfunctions:///***initializethesystem*@return0UNKNOWNfilesystem*@return1FAT16filesystem*@return3couldnotsetblocklength*@return4couldnotinitializememorycard**/unsignedcharfat_initialize

7、(void);*closesthefileindicatedbytheinput**@paramfileHandle*handleoffiletobeclosed*@return0filesucessfullyclosed*@return-1*@return-2invalidfilehandleinvalidfilesystem*@return-4filealreadyopenedforreading*@return-4filealreadyopenedforreadingsignedcharfat_close(signedcharfileHandle);/***opensthe

8、fileindicatedbytheinputpathname.Ifthepathname*pointstoavalidfile,thefileisaddedtothelistofcurrently*openedfilesforreadingandtheuniquefilehandleisreturned.@parampathnameapointertothelocationofthefiletobeopened*@parambufthebuffertobeusedtoaccesstheMMC/SDcard*@return-4filealreadyopenedforreading

9、*@return-4filealreadyopenedforreading*@return-1invalidpathname*@return-4filealreadyopenedforreadingfiledoesnotexist*@return-4filealreadyopenedforreading*@return-3filealreadyopenedforwriting*@return-4filealreadyopenedforreading*@return-10*@ret