/*****************************************************************************\*              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;		/* 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);}