uCFS開發(fā)詳解

1、uC/FS詳解(開發(fā)文檔)1： uC/FS簡(jiǎn)介   µC/FS is a FAT file system which can be used on any media, for which you can provide basic hardware access functions. . µC/FS is a high performance library that has been optimized for speed, versatility and memory footp

2、rint.   文件配置表（英文：File Allocation Table，首字母縮略字：FAT）是一種由微軟發(fā)明的并帶有部分專件系統(tǒng)。FAT文件系統(tǒng)考慮當(dāng)時(shí)計(jì)算機(jī)效能有限，所以未被復(fù)雜化，因而被幾乎所有個(gè)人計(jì)算機(jī)的操作系統(tǒng)支持。這特性使它成為理想的軟盤和記憶卡文件系統(tǒng)，也適合用作不同操作系統(tǒng)中的數(shù)據(jù)交流。但FAT有一個(gè)嚴(yán)重的缺點(diǎn)：當(dāng)文件被刪除并且在同一位置被寫入新數(shù)據(jù)，他們的片段通常是分散的，減慢了讀寫速度。磁盤碎片重整是一種解決方法，但必須經(jīng)常重組來保持FAT文件系統(tǒng)的效率。 FAT文件系統(tǒng)遵行已用了多年的軟件方法來進(jìn)行規(guī)范。它在1977年由比爾&

3、#183;蓋茨和馬斯·麥當(dāng)勞為了管理磁盤而發(fā)明。2： uC/FS特點(diǎn)µC/FS is written in ANSI C and can be used on virtually any CPU. Some features of µC/FS are: ·  MS-DOS/MS-Windows compatible FAT12 and FAT16 support. ·  Multiple device driver support. You can use different devi

4、ce drivers with µC/FS, which allows           you to access different types of hardware with the file system at the same time. 【在該文件系統(tǒng)中可同時(shí)支持多個(gè)設(shè)備驅(qū)動(dòng)】·  Multiple media support. A device driver does allow you to access different&

5、#160;medias at the same            time. ·  OS support. µC/FS can easily be integrated into any OS. In that way you can make file operations        in a multithreaded environment. 

6、·  ANSI C stdio.h like API for user applications. An application using standard C I/O library can             easily be ported to use µC/FS. ·  Very simple device driver structure. µC/FS device driver

7、s need only very basic functions for                 reading and writing blocks. Therefore it is very simple to support your custom hardware. ·  Generic device driver for SmartMedia cards, which

8、can easily be used with any kind of card                  reader hardware. ·  Generic device driver for MultitMedia & SD cards using SPI mode, which can be easily integrated.3： uC/F

9、S結(jié)構(gòu)   µC/FS 由不同的分層構(gòu)成。 上面的圖是FATFS,但與UC/FS的是一樣的   1：API層【類似于linux的VFS層】      The API layer is the interface between µC/FS and the user application. It does contain a library of ANSI C oriented file functions, such as  

10、;FS_FOpen, FS_FWrite etc. The API layer does transfer these calls to the file system layer. Currently there is only a FAT file system layer available for µC/FS, but the API layer can deal with different file system layers at the same time. So it is possible to use FAT and an

11、y other file system at the same time with µC/FS.      API層是µC/FS 提供給用戶使用的接口層（fs_api.h），API層將各種調(diào)用傳輸?shù)絝ile system layer（文件系統(tǒng)層），目前對(duì)µC/FS（文件管理實(shí)現(xiàn)機(jī)制）來說 只有一個(gè) FAT文件系統(tǒng)層被使用，API層可以處理不同的文件系統(tǒng)層，因此µC/FS可同時(shí)支持多種文件系統(tǒng)（API層類似于linux中的虛擬文件系統(tǒng)VFS，他的功能是提供給童用戶標(biāo)準(zhǔn)的系統(tǒng)調(diào)用接口，VFS層下面才

12、是具體實(shí)際的文件系統(tǒng)層，有FAT、EXT2等等，這個(gè)根據(jù)硬件的情況（格式化時(shí)使用什么文件系統(tǒng)）來調(diào)用具體的文件系統(tǒng)）。   2：File System Layer 文件系統(tǒng)層【這層與linux是一樣的，是具體的管理文件所用的文件系統(tǒng)】   The file system layer translates file operations to logical block operations. After such a translation, the file system calls the logical block l

13、ayer and specifies the corresponding device driver for a device.   文件系統(tǒng)層將文件操作轉(zhuǎn)換為邏輯塊操作，之后，具體的文件系統(tǒng)調(diào)用邏輯塊層函數(shù)并指定設(shè)備相應(yīng)的驅(qū)動(dòng)；【linux中，文件系統(tǒng)將各種系統(tǒng)調(diào)用轉(zhuǎn)換為各種IO請(qǐng)求（系統(tǒng)請(qǐng)求即是對(duì)底層相應(yīng)的扇區(qū)、柱面、等操作），IO請(qǐng)求被放到對(duì)應(yīng)設(shè)備的IO請(qǐng)求隊(duì)列中去，再由一個(gè)系統(tǒng)內(nèi)核線程一直讀取請(qǐng)求隊(duì)列中的請(qǐng)求，沒有請(qǐng)求時(shí)就睡眠，拿到請(qǐng)求就通過設(shè)備驅(qū)動(dòng)實(shí)現(xiàn)具體的操作】    uC_FSFSLfat 下面就是F

14、AT文件系統(tǒng)的各個(gè)文件。   3：Logical Block Layer 邏輯塊層   the main purpose of the logical block layer is to synchronize accesses to a device driver and to have an easy interface for the file system layer.  The logical block layer does call a device driver to make a blo

15、ck operation.    邏輯塊層的主要目的是同步訪問設(shè)備驅(qū)動(dòng)與文件系統(tǒng)的簡(jiǎn)易接口，邏輯塊層調(diào)用設(shè)備驅(qū)動(dòng)來實(shí)現(xiàn)設(shè)備的塊操作。   4： Device Driver Layer 設(shè)備驅(qū)動(dòng)層   Device drivers are low level routines that are used to access your hardware. The structure of the device driver is simple to allow

16、 easy integration of your own hardware.  設(shè)備驅(qū)動(dòng)是一些訪問硬件的底層操作，µC/FS的設(shè)備驅(qū)動(dòng)的架構(gòu)很簡(jiǎn)單，不像linux架構(gòu)非常復(fù)雜。 4： uC/FS的使用   下面的流程是參考uC/FS用戶手冊(cè)上的例程來寫的，可以參考。   1:調(diào)用FS_Init()初始化文件系統(tǒng)，在使用uC/FS的任何功能函數(shù)之前須要首先調(diào)用該函數(shù)進(jìn)行初始        化； &

17、#160; 2：進(jìn)入MainTask()           1：調(diào)用FS_IoCtl()【格式化：使硬件按指定的文件系統(tǒng)來管理文件】              This call is used to format your RAM disk in order to be able to write data to  

18、;                   it. Formatting your RAM disk should not cause any problem.           2：調(diào)用應(yīng)用程序中的函數(shù)_write_file()【非uc/fs的函數(shù)】   &#

19、160;             _write_file()中又依次調(diào)用： FS_FOpen()， FS_FWrite()，F(xiàn)S_FClose()              FS_FOpen()：在這個(gè)例程中FS_FOpen()創(chuàng)建了一個(gè)叫default.txt的文件，如果創(chuàng)建成功，函數(shù)  

20、0;                        將返回一個(gè)FS_FILE結(jié)構(gòu)體的指針，如果出錯(cuò)將返回0              FS_FWrite()：文件創(chuàng)建成功之后，將一串字符串寫入該文件中，如果寫入時(shí)出錯(cuò)，例

21、程中調(diào)                              用FS_FError()處理錯(cuò)誤。              FS_FClose()：關(guān)閉上面打開的文件

22、，返回主任務(wù)中    【大致過程就是如上過程】     讀： FS_FOpen()->FS_FRead()->FS_FClose()   3:不使用uC/FS文件管理系統(tǒng)時(shí)調(diào)用FS_Exit().5： uC/FS加入到工程中   1：Create a simple project without µC/FS       We recom

23、mend, that you create a small “hello world” program for your system. That project should already use your OS and there should be a way to display text on a screen or serial port.    2: Add your µC/FS configuration      In order to

24、 configure  µC/FS for your system, you should create a new sub-directory in µC/FSs config directory and copy the files  fs_conf.h  and fs_port.h from one of the other sub-directories to your directory. For the following chapters, we assume that

25、you have created a directory FSCONFIGmyconfig. Usually, the only file  you have to modify is fs_conf.h. For an easy startup, we recommend, that you disable all drivers except the RAM disk driver. Please check out the chapter “Configuration of µC/FS” for detailed informa

26、tion about the configuration.     3: Add µC/FS generic source code      Add all source files in the following directories:        FSAPI: µC/FS提供給用戶的接口函數(shù)     

27、60;  FSFSL: 具體的文件系統(tǒng)層        FSLBL: 邏輯塊層         FSOS :        FSDEVICERAM      and their sub-directories to your project.   &

28、#160; 4: Configure the search path為開發(fā)環(huán)境添加所以代碼的路徑        FSAPI         FSCONFIGmyconfig         FSLBL         FSOS&#

29、160;  5: Add generic sample code       For a quick and easy test of your µC/FS integration, you should use the code        found in FSsamplemain.c.   6： uC/FS配置 1：fs_conf.h  &

30、#160;  This is the main configuration file for the file system. You define which drivers you want to use and, the configurations for these drivers.      【用戶手冊(cè)中列出了一個(gè)配置樣本】，包括下面的各個(gè)配置項(xiàng)目    1：OS support      &#

31、160;You can specify whether you are using uC/OS-II, embOS, Windows or no OS support at all.  Please set  FS_OS_UCOS_II,  FS_OS_EMBOS, FS_OS_WINDOWS to 1, respectively. For no OS support at all, set all of them to 0. If you need support for an additional OS, you will hav

32、e to provide functions described in the chapter “OS integration”.     2：Time/Date support       If you want to be able to add date and times to your files, you will need to set FS_OS_TIME_SUPPORT  to 1.    

33、; 3：File System Layer Support      µC/FS can support different file system at the same time. You can enable them by setting FS_USE_XXX_FSL, where XXX is the name of the file system layer. The current version of µC/FS only supports the FAT file s

34、ystem, so you will need to set FS_USE_FAT_FSL to 1.   4：Device Driver Support and configurationI      RAM Disk:            FS_USE_RAMDISK_DRIVER  to  1     

35、0; Windows Driver:    FS_USE_WINDRIVE_DRIVER to 1            Smart Media Card（SMCs）:                      

36、0;    FS_USE_SMC_DRIVER  to 1       MultiMedia card:             µC/FS can support  MultiMedia & SD cards. You can enable the driver by setting FS_USE_MMC_D

37、RIVER to 1. In order to use it, you will have to provide low-level I/O functions for your card reader hardware. Please take a look at the chapter “MultiMedia & SD card device driver” for details.       CompactFlash card & IDE：FS_USE_IDE_

38、DRIVER to 1  2：fs_port.h【一般是與CPU相關(guān)的數(shù)據(jù)類型】      Usually this file only requires minor modifications, if you are using a very specific CPU. Please also check the type declarations in this file to ensure that they fit with your target processor and compi

39、ler. 6： API函數(shù)說明   FS_IoCtl：執(zhí)行命令（SD卡等可以通過電腦格式化）   x = FS_IoCtl("ram:",FS_CMD_FORMAT_MEDIA,FS_MEDIA_RAM_16KB,0);  Directory functions  int FS_CloseDir(FS_DIR *dirp);  int FS_MkDir(const char *dirname);  FS_DIR *F

40、S_OpenDir(const char *dirname);  struct FS_DIRENT *FS_ReadDir(FS_DIR *dirp);  void FS_RewindDir(FS_DIR *dirp);   int FS_RmDir(const char *dirname); 7： 設(shè)備驅(qū)動(dòng)Device drivers  µC/FS可以與任何種類的硬件配合工作；µC/FS需要配備與硬件設(shè)備對(duì)應(yīng)的設(shè)備驅(qū)動(dòng)程序，這些設(shè)備驅(qū)動(dòng)程序包含 基本的訪問硬件的I

41、/O函數(shù) 以及 一張全局表，這張表中存放各個(gè)函數(shù)的指針?！韭?lián)想到LINUX中系統(tǒng)調(diào)用的系統(tǒng)調(diào)用號(hào)】  要使你的µC/FS支持特定的硬件設(shè)備，你必須寫好該設(shè)備的驅(qū)動(dòng)，本節(jié)告訴你需要實(shí)現(xiàn)哪些函數(shù)以及怎么樣將驅(qū)動(dòng)整合到µC/FS中去。   【下面是ramdisk的設(shè)備驅(qū)動(dòng)函數(shù)表的例子：設(shè)備驅(qū)動(dòng)函數(shù)表中的各個(gè)函數(shù)，在PDF中已給出具體的代碼，其他的設(shè)備，如MMC&SD也是類似的，需要提供這相關(guān)的幾個(gè)函數(shù)，名字可以不同，在功能函數(shù)的次序要一樣】      In thi

42、s chapter, you will find a detailed description of the device driver functions required by µC/FS. Please note that the names used for these functions are not really relevant for  µC/FS because the file system accesses those functions through a function table.  

43、;因?yàn)槭峭ㄟ^一張全局表來管理各個(gè)設(shè)備驅(qū)動(dòng)函數(shù)，所以各設(shè)備驅(qū)動(dòng)函數(shù)的名稱與µC/FS沒有太多的關(guān)聯(lián)性。  _FS_DevIoCtl()：Execute special command on device.     static int _FS_DevIoCtl(FS_u32 id, FS_i32 cmd, FS_i32 aux,void *buffer);             

44、0;                 Parameter  Meaning                             

45、; id         Number of media (0N)                              cmd       &#

46、160;Command                              aux        Parameter for command       

47、                       buffer     Pointer to data required by command     該函數(shù)被用來完成一些設(shè)備驅(qū)動(dòng)中特殊的命令，對(duì)uc/FS來說目前需要支持的這類特殊命令有：FS_CMD_FLUSH_CACHE，這個(gè)命

48、令用來告訴設(shè)備的緩沖邏輯 所有的緩沖必須清零，如果你的設(shè)備沒有緩沖邏輯，該函數(shù)不需要做任何事情。  _FS_DevRead()：Read block from media       static int _FS_DevRead(FS_u32 id, FS_u32 block, void *buffer);                 

49、;             id      Number of media (0N)                            

50、  block   Block number to be read from the media                              buffer  Data buffer to which the data is transf

51、erred   The function should transfer 0x0200 (i.e. 512) bytes, which is the default value for an MS-DOS/MS-Windows compatible FAT file systems. µC/FS can support any block size but, if you use the FAT file system layer, you have to use this default block size. 

52、   函數(shù)應(yīng)該傳送0x0200(512)個(gè)字節(jié)，這個(gè)是兼容FAT文件系統(tǒng)的MS-DOS/MS-Windows系統(tǒng)的默認(rèn)值，µC/FS能支持任何大小的塊，但是如果你的文件系統(tǒng)層使用FAT，那么你必須使用這個(gè)默認(rèn)的塊大小。  _FS_DevStatus()：Return current status of your device.      static int _FS_DevStatus(FS_u32 id); id  Number of media (0N

53、)    The main purpose of this function is to detect a media change. All µC/FS file operation calls this function to check, if the device can be accessed.   該函數(shù)的主要目的是檢測(cè)一個(gè)介質(zhì)的改變。如果一個(gè)設(shè)備能夠被訪問，所有的µC/FS 文件操作都調(diào)用這個(gè)函數(shù)進(jìn)行檢測(cè)，   The function re

54、turns 0 if the device can be accessed. If the media has changed (e.g. a card removed or replaced) and the device can be accessed, the return value has to be FS_LBL_MEDIACHANGED. Any value < 0 is interpreted as an error.   _FS_DevWrite()：Write block to media 

55、0;     static int _FS_DevWrite(FS_u32 id, FS_u32 block,void *buffer);                              id     

56、; Number of media (0N)                               block   Block number to be written on media     

57、0;                         buffer  Pointer to data for transfer to the media.       The function should transfer 0x0200 (i.e. 512) byte

58、s, which is the default value for an MS-DOS/MS-Windows compatible FAT file systems. µC/FS can support any block size but, if you use the FAT file system layer, you have to use this default block size.   Device driver function table   To use a device

59、driver with µC/FS, a global function table is required, which   holds pointers to the device driver functions.  Each entry in the table contains   five values as shown in the example below.      const FS_device_type FS_ramdevice_driver = &#

60、160;       "RAMDISK device",        _FS_DevStatus,        _FS_DevRead,        _FS_DevWrite,       &#

61、160;_FS_DevIoCtl           If you want to use your own device driver, you have to tell µC/FS, which device name you would like to use for your device and which  File System Layer (currently only FAT is supported) you want to

62、use.     You do this by setting appropriate value for FS_DEVINFO in your FS_conf.h , which is used to initialize µC/FSs global device information table.     如果你想要使用自己的設(shè)備驅(qū)動(dòng)，你必須要告訴C/FS，你的設(shè)備使用的是哪一個(gè)設(shè)備名稱以及使用哪一個(gè)文件系統(tǒng)來管理（目前只支持FAT）。   可以將&

63、#160;FS_conf.h中的FS_DEVINFO 設(shè)置一個(gè)合適的值來完成上面的動(dòng)作，F(xiàn)S_DEVINFO被用來初始化C/FS的全局設(shè)備信息表。 【上面是ramdisk的設(shè)備驅(qū)動(dòng)函數(shù)表的例子，_FS_DevStatus, _FS_DevRead, _FS_DevWrite,  _FS_DevIoCtl，就是ramdisk所需的底層驅(qū)動(dòng)函數(shù)】  這里如果是MMC&SD存儲(chǔ)設(shè)備，下面是源碼。#ifndef FS_DEVINFO #if FS_USE_SMC_DRIVER  

64、60;#define FS_DEVINFO_DEVSMC           "smc",&FS_fat_functable,&FS_smcdevice_driver,FS_CACHEINFO_SMC_DRIVER 0 , #else   #define FS_DEVINFO_DEVSMC #endif  #if FS_USE_MMC_DRIVER   #def

65、ine FS_DEVINFO_DEVMMC          "mmc", &FS_fat_functable,&FS_mmcdevice_driver, FS_CACHEINFO_MMC_DRIVER 0 , #else   #define FS_DEVINFO_DEVMMC #endif . #endif從源碼中可以看出，如果沒有定義  FS_DEVINFO宏，且如果沒有定義 

66、FS_DEVINFO_DEVSMC，系統(tǒng)會(huì)自動(dòng)以FS_DEVINFO_DEVSMC，即采用系統(tǒng)默認(rèn)的設(shè)備驅(qū)動(dòng)。我們可以在fs_conf.h中配置    FS_USE_MMC_DRIVER = 1；再定義 #define FS_DEVINFO          "mmc",    &FS_fat_functable, &FS_mmcdevice_driver, 0,FS_USE_MMC_DRIVER = 1,即使

67、沒有定義 FS_DEVINFO,系統(tǒng)也會(huì)有一個(gè)默認(rèn)的定義。FS_fat_functable：這個(gè)表不用填充，因?yàn)檫@里面的函數(shù)在API層已經(jīng)實(shí)現(xiàn)，且系統(tǒng)已經(jīng)設(shè)置好。用戶只需更改FS_mmcdevice_driver里面的各個(gè)函數(shù)即可。 【這里支持多個(gè)設(shè)備"smc"和"mydev"】#define FS_DEVINFO          "smc",    &FS_fat_functable,

68、 &FS_smcdevice_driver, 0,          "mydev",  &FS_fat_functable, &FS_mydevice_driver , 0 【如果不指定，系統(tǒng)將使用默認(rèn)值】   The first parameter is a device name, which you want to use for  µC/FSs API calls.

69、60;   The second parameter is a pointer to a  File System Layer function table; currently only FAT is supported.     The third parameter is a pointer to a Device Driver function table.     The last parameter is reserved for future use and should be zero.  8： 各目錄介紹 在工程中添加上面的文件組：API層、FAT層、LBL層、DEV層、OS、CLIBDEV包含的就是文件系統(tǒng)需要使用的最底層的操作硬