mkfs.c

最新版IAR FOR ARM（EWARM）5.11中的代码例子

/*****************************************************************************\
*              efs - General purpose Embedded Filesystem library              *
*          --------------------- -----------------------------------          *
*                                                                             *
* Filename : mkfs.c                                                           *
* Description : These functions are used for creating an empty filesystem.    *
*                                                                             *
* This program is free software; you can redistribute it and/or               *
* modify it under the terms of the GNU General Public License                 *
* as published by the Free Software Foundation; version 2                     *
* of the License.                                                             *
                                                                              *
* This program is distributed in the hope that it will be useful,             *
* but WITHOUT ANY WARRANTY; without even the implied warranty of              *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               *
* GNU General Public License for more details.                                *
*                                                                             *
* As a special exception, if other files instantiate templates or             *
* use macros or inline functions from this file, or you compile this          *
* file and link it with other works to produce a work based on this file,     *
* this file does not by itself cause the resulting work to be covered         *
* by the GNU General Public License. However the source code for this         *
* file must still be made available in accordance with section (3) of         *
* the GNU General Public License.                                             *
*                                                                             *
* This exception does not invalidate any other reasons why a work based       *
* on this file might be covered by the GNU General Public License.            *
*                                                                             *
*                                                    (c)2006 Lennart Yseboodt *
*                                                    (c)2006 Michael De Nil   *
\*****************************************************************************/

/*****************************************************************************/
#include "mkfs.h"
/*****************************************************************************/

signed short mkfs_makevfat(Partition *part)
{
    unsigned long c,cc,ret;
    unsigned long ns,fs,ds,dc;
    unsigned char buf[512];

    ns=part->disc->partitions[part->activePartition].numSectors;

    if( ns < 66581 ){
        DBG((TXT("This is not possible due to insufficient sectors. Sorry\n")));
        return(MKFS_ERR_TOOLITTLESECTORS);
    }

    ret=0;

    for(c=1<<6;c>=1;c>>=1){

        /* First guess */
        ds = ns - 32;
        fs = ((ds/c)+127)/128;
        /* ds was guess too large, so fs is too large now too. */

        for(cc=0;cc<2;cc++){

            /* Round 2, error round */
            ds = ns - 32 - 2*fs;
            fs = ((ds/c)+127)/128;
            /* Since fs was too large, ds became too small. So the fs for this small ds is too small as well. */

            /* Round 3, correction round */
            ds = ns - 32 - 2*fs;
            fs = ((ds/c)+127)/128;
            /* The fs was too small, so ds was too large. The calculated fs should be slightly too large. */

        }

        /* Round 4, finalise */
        ds = ns - 32 - 2*fs;

        dc = ds / c;
        if(ret<(fs*128-dc)/128)ret=(fs*128-dc)/128;

        /* Check if with current setting we have a valid fat ? */

        if(dc >= 65525 + 16){
            break;
        }
    }

    /* Generate BPB */
    memClr(buf,512);

    /* Boot code */
    *(buf+0)=0xE9;  *(buf+1)=0x00;  *(buf+2)=0x00; /* RESET */

    /* OEM name */
    memCpy("DSCOSMSH",buf+3,8);

    /* Bytes/Sector */
    *((unsigned short*)(buf+11)) = 512;

    /* Sectors/Cluster */
    *(buf+13) = c;

    /* Reserved Sectors */
    *((unsigned short*)(buf+14)) = 32;

    /* Number of FAT Tables */
    *(buf+16) = 2;

    /* RootEntryCount */
    *((unsigned short*)(buf+17)) = 0;

    /* Total Sector Count __16 */
    *((unsigned short*)(buf+19)) = 0;

    /* Media (crap) */
    *(buf+21) = 0xF8;

    /* FAT size 16 */
    *((unsigned short*)(buf+22)) = 0;

    /* Total Sector Count __32 */
    *((unsigned long*)(buf+32)) = ns;

    /* Fat Size 32 */
    *((unsigned long*)(buf+36)) = fs;

    /* First Cluster Root Dir */
    *((unsigned long*)(buf+44)) = 2;

    /* VolumeID */
    //*((unsigned long*)(buf+67)) = 0x13371337;
    *((unsigned char*)(buf+67 + 0)) = (0x13371337 >> 0) & 0xff;
    *((unsigned char*)(buf+67 + 1)) = (0x13371337 >> 8) & 0xff;
    *((unsigned char*)(buf+67 + 2)) = (0x13371337 >>16) & 0xff;
    *((unsigned char*)(buf+67 + 3)) = (0x13371337 >>24) & 0xff;

    /* Volume Label */
    memCpy("DISCOSMASH!",buf+71,11);

    /* Filesystemtype */
    memCpy("FAT32   ",buf+82,8);

    /* Magic */
    *(buf+510) = 0x55; *(buf+511) = 0xAA;

    part_writeBuf(part,0,buf);

    memClr(buf,512);
    for(c=32;c<(32+2*fs);c++){
        part_writeBuf(part,c,buf);
    }
    *(((unsigned long*)buf)  )=0x0FFFFFF8;
    *(((unsigned long*)buf)+1)=0x0FFFFFFF;
    *(((unsigned long*)buf)+2)=0x0FFFFFF8;
    part_writeBuf(part,32,buf);
    part_writeBuf(part,32+fs,buf);

    return(0);
}