fat.c

nec16位单片机读U盘播放MP3源码

#pragma sfr
#pragma NOP
#pragma DI
#pragma EI

#include "Common.h"
#include "Define.h"
#include "Ch375.h"
#include "Fat.h"
#include "Hpi.h"

////////////////////////////////////////
extern sreg XXGFLAGS  bXXGFlags;
extern SYS_INFO_BLOCK  DeviceInfo;
extern FILE_INFO  ThisFile;
extern FILE32_INFO ThisFile32;
extern unsigned char  DBUF[BUFFER_LENGTH];
extern unsigned char  FATBUF[512];
extern unsigned char  CurFatSector[512];
extern FREE_FAT_INFO  FreeFat;
////////////////////////////////////////
unsigned long FirstSectorofCluster(unsigned int clusterNum)
{
	unsigned long temp;
	temp=clusterNum-2;
	temp=temp*DeviceInfo.BPB_SecPerClus;
	temp=temp+DeviceInfo.FirstDataSector;
	return temp;
}
unsigned int ThisFatSecNum(unsigned int clusterNum)
{
   unsigned int temp;
   temp=clusterNum*2;
   temp=temp/DeviceInfo.BPB_BytesPerSec;
   temp=temp+DeviceInfo.FatStartSector;
   return temp;
}

/*unsigned long ThisFatSecNum32(unsigned long clusterNum)
{
   unsigned long temp;
   temp=clusterNum*2;
   temp=temp/DeviceInfo.BPB_BytesPerSec;
   temp=temp+DeviceInfo.FatStartSector;
   return temp;
}*/
unsigned int ThisFatEntOffset(unsigned int clusterNum)
{
	unsigned int temp1,temp2;
	temp1=2*clusterNum;
	temp2=temp1/DeviceInfo.BPB_BytesPerSec;
	temp1=temp1-temp2*DeviceInfo.BPB_BytesPerSec;
	return temp1;
}

/*unsigned long ThisFatEntOffset32(unsigned long clusterNum)
{
	unsigned long temp1,temp2;
	temp1=2*clusterNum;
	temp2=temp1/DeviceInfo.BPB_BytesPerSec;
	temp1=temp1-temp2*DeviceInfo.BPB_BytesPerSec;
	return temp1;
}*/
unsigned int GetNextClusterNum(unsigned int clusterNum)
{
	unsigned int xxgFatSecNum,xxgFatEntOffset;
	
	xxgFatSecNum=ThisFatSecNum(clusterNum);
	xxgFatEntOffset=ThisFatEntOffset(clusterNum);
	//ThisFile.FatSectorPointer=xxgFatSecNum;
	if(ThisFile.FatSectorPointer!=xxgFatSecNum)
	{	
		
		if(!RBC_Read(xxgFatSecNum,1,FATBUF))
			return 0xFFFF;
		ThisFile.FatSectorPointer=xxgFatSecNum;
	}
	
	///////////////////////////////////////////////////
	clusterNum=FATBUF[xxgFatEntOffset+1];
	clusterNum=clusterNum<<8;
	clusterNum+=FATBUF[xxgFatEntOffset];	
	return clusterNum;
}

/*unsigned long GetNextClusterNum32(unsigned long clusterNum)
{
	unsigned long xxgFatSecNum,xxgFatEntOffset;
	
	xxgFatSecNum=ThisFatSecNum32(clusterNum);
	xxgFatEntOffset=ThisFatEntOffset32(clusterNum);
	if(ThisFile.FatSectorPointer!=xxgFatSecNum)
	{	
		
		if(!RBC_Read(xxgFatSecNum,1,FATBUF))
			return 0xFFFF;
		ThisFile.FatSectorPointer=xxgFatSecNum;
	}
	
	///////////////////////////////////////////////////
	clusterNum=FATBUF[xxgFatEntOffset+1];
	clusterNum=clusterNum<<8;
	clusterNum+=FATBUF[xxgFatEntOffset];	
	return clusterNum;
}*/