fat16.c

用89C51SND1C实现MP3播放器的源代码.用KEIL c51编写.

/****************************************************************/
/*					UP-MP3DIY100								*/
/*		Beijing Universal Pioneering Technology Co., LTD		*/
/*		CopyRighted,All right Reserved	www.up-tech.com			*/
/*						July,2003								*/
/*				010-62387873  62381842							*/
/****************************************************************/

#include "Fat16.h"
#include "Flash.h"
#include "uart.h"
#include "string.h"

//数据结构与全局变量定义
extern unsigned char Page_Buf[];
extern unsigned char SONG[];

long int Current_Cluster,DataRead=0,DataRemain=0,Sector_Offset=0x21d;


unsigned int TotalCluster,BootSector,RsdSector,SectorofFatSize,TotalCapacity,RootEntry,SecPerClus,TotalSector,BytesPerSec,FirstDataSec;
unsigned char FAT_TYPE;

void Init_FAT_Info(void)
{
	int i;

	///////////////////////////////////////////////////
	//得到引导扇区所在扇区号，如果介质是不带分区的，则0扇区就是BootSector了。
	ReadPage(Begin_Cluster,0,Page_Buf);

	if(!(Page_Buf[0]==0xeb&&Page_Buf[2]==0x90)){	//通过判断EB ?? 90来看是否已经是BPB了
		//带分区的介质
		BootSector=Page_Buf[454]+Page_Buf[455]*256+Page_Buf[456]*(256*256)+Page_Buf[457]*(256*256*256);
		}
	else BootSector=0;
	///////////////////////////////////////////////////

	////////////////////////////////////////////////
	//得到保留扇区数,总扇区数,总扇区数／每簇扇区数得到簇数，是FAT类型的依据
	ReadPage(Begin_Cluster,BootSector,Page_Buf);
	RsdSector=Page_Buf[14]+Page_Buf[15]*256;
	SecPerClus=Page_Buf[13];

	BytesPerSec=Page_Buf[12]*256+Page_Buf[11];

	TotalSector=(Page_Buf[20]*256+Page_Buf[19]);
	TotalCapacity=TotalSector*BytesPerSec;
	TotalCluster=TotalSector/SecPerClus;//FAT16的簇总数=扇区总数/每簇扇区数

	SectorofFatSize=((Page_Buf[22]+Page_Buf[23]*256));
	RootEntry=(Page_Buf[18]*256+Page_Buf[17]);

	FirstDataSec=BootSector+RsdSector+(SectorofFatSize*2)+((RootEntry*32+(BytesPerSec-1))/BytesPerSec);

	if(TotalCluster>65525){  //FAT32的扇区总数和FAT表项长度
		FAT_TYPE=FAT32;

		if(TotalSector==0) TotalSector=(Page_Buf[32]+Page_Buf[33]*256+Page_Buf[34]*256*256+Page_Buf[35]*256*256*256);
		TotalCapacity=TotalSector*BytesPerSec;
		TotalCluster=TotalSector/SecPerClus;

		SectorofFatSize=(Page_Buf[36]+Page_Buf[37]*256+Page_Buf[38]*256*256+Page_Buf[39]*256*256*256);
		if(SectorofFatSize>(TotalCluster*16/512)) SectorofFatSize=((Page_Buf[22]+Page_Buf[23]*256));
		RootEntry=(Page_Buf[44]*256+Page_Buf[43]);
		FirstDataSec=BootSector+RsdSector+(SectorofFatSize*2)+((RootEntry*32+(BytesPerSec-1))/BytesPerSec);
		
		}
	else if((TotalCluster>0)&&(TotalCluster<4085)) {//FAT12
		FAT_TYPE=FAT12;
		}
	else {	//FAT16
		FAT_TYPE=FAT16;
		}
	
}

unsigned char GetMP3List(void)
{
	unsigned char i=0,j=0,l=0;
	int k=0;
	unsigned char MP3[3]={'M','P','3'};
	Init_FAT_Info();

	k=BootSector+RsdSector+2*SectorofFatSize;
	printuf("BootSector:%x",BootSector);
	printuf("RsdSector:%x",RsdSector);
	printuf("SectorofFatSize:%x",SectorofFatSize);

	printuf("RootDIR:%x",(k&0xff00)>>8);
	printuf("%x\n",k);

	ReadPage(0+k/32,k%32,Page_Buf);

	while(Page_Buf[0]!=0){//遍历整个目录
		for(j=0;j<16;j++){
				if(!Page_Buf[j*32]) break;
				if(Page_Buf[j*32]==0xE5) continue;

				if(!memcmp(MP3,&Page_Buf[j*32+8],3)){	//file find
					for(i=0;i<11;i++) SONG[l*11+i]=Page_Buf[j*32+i];
					l++;
					}
				}
		k++;
		ReadPage(0+k/32,k%32,Page_Buf);
		}
	return(l);
}
int ReadSector(unsigned char *Name,unsigned char *databuff)
{
	int i,j,k,Page;
	if(DataRead==0) //第一次读取，先查找文件，然后进行读取
		{
			Page=BootSector+RsdSector+2*SectorofFatSize;
			ReadPage(0+Page/32,Page%32,databuff);
			while(databuff[0]!=0){//遍历整个目录
			for(i=0;i<16;i++){
							if(!memcmp(Name,&databuff[i*32],11)){
								Current_Cluster=databuff[32*i+27]*256+databuff[32*i+26];
								printuf("Current_Cluster:%x",(Current_Cluster&0xff00)>>8);
								printuf("%x\n",Current_Cluster);
								for(k=31;k>27;k--) DataRemain=(DataRemain<<8)|databuff[i*32+k];
								ReadPage((Current_Cluster+Sector_Offset)/32,(Current_Cluster+Sector_Offset)%32,databuff);

								DataRead+=512;
								DataRemain-=512;
								if(DataRemain<0) {DataRead=0;return(DataRemain+512);}
								else return(512);
							}
						}
				Page++;
				ReadPage(0+Page/32,Page%32,databuff);
		  }
		  printu("\nfile is not found!");return(0);
		}
	else
		{
//			if((Current_Cluster+Sector_Offset+DataRead/BytesPerSec)%32) Current_Cluster=NextCluster(Current_Cluster);
			ReadPage((Current_Cluster+Sector_Offset)/32,(Current_Cluster+Sector_Offset+DataRead/BytesPerSec)%32,databuff);
			DataRead+=512;
//			if(!((Current_Cluster+Sector_Offset+DataRead/BytesPerSec)%32)) Current_Cluster=NextCluster(Current_Cluster+32);
			if(!((Current_Cluster+Sector_Offset+DataRead/BytesPerSec)%32)) Current_Cluster+=32;//默认歌曲文件是顺序存放的。
			DataRemain-=512;
			if(DataRemain<0) {DataRead=0;return(DataRemain+512);}
			else return(512);
			}

}

unsigned int NextCluster(unsigned int CurrentCluster)
{
	unsigned int i,j;
	if(FAT_TYPE==FAT12){
		ReadPage(Begin_Cluster+(BootSector+RsdSector+(CurrentCluster*3/2)/BytesPerSec)/SecPerClus,(BootSector+RsdSector+(CurrentCluster*3/2)/BytesPerSec)%SecPerClus,Page_Buf);
		if(CurrentCluster%2==0) {
			j=Page_Buf[(CurrentCluster*3/2)%BytesPerSec+1];
			i=Page_Buf[(CurrentCluster*3/2)%BytesPerSec]|(j<<8);
			i&=0x0fff;
			}
		else {
			j=Page_Buf[(CurrentCluster*3/2)%BytesPerSec+1];
			i=Page_Buf[(CurrentCluster*3/2)%BytesPerSec]|(j<<8);
			i=(i>>4);
			}
		return (i);
		}
	else if(FAT_TYPE==FAT16){
		ReadPage(Begin_Cluster+(BootSector+RsdSector+(CurrentCluster*2)/BytesPerSec)/32,(BootSector+RsdSector+(CurrentCluster*2)/BytesPerSec)%32,Page_Buf);
		i=Page_Buf[(CurrentCluster*2)%BytesPerSec+1]*256+Page_Buf[(CurrentCluster*2)%BytesPerSec];
		return (i);
		}
	else if(FAT_TYPE==FAT32){
		ReadPage(Begin_Cluster+(BootSector+RsdSector+(CurrentCluster*4)/BytesPerSec)/SecPerClus,(BootSector+RsdSector+(CurrentCluster*4)/BytesPerSec)%SecPerClus,Page_Buf);
		i=Page_Buf[(CurrentCluster*4)%BytesPerSec+3]*256*256*256+Page_Buf[(CurrentCluster*4)%BytesPerSec+2]*256*256+Page_Buf[(CurrentCluster*4)%BytesPerSec+1]*256+Page_Buf[(CurrentCluster*4)%BytesPerSec];
		return (i);
		}
}