file_sys.c

基于at89c51单片机的mp3 mp3播放实验资料及代码

#include <string.h>
#include "AT89C51SND1_REG.H"
#include "FILE_SYS.H"
#include "MCU_UART.H"

unsigned char PageBuf[512];
unsigned char FAT_TYPE; 

unsigned char  SecPerClus;
unsigned int   RsdSecCnt,BytesPerSec,RootEntCnt,FatSize16;
unsigned long  TotalSector,FatStartSec,RootStartSec,FirstDataSec;

unsigned long  CurrentClus,CurrentSec,DataRemain = 0;

#define BootSector  0

void Init_FAT_Info(void)
{
	ReadPage(BootSector,PageBuf);
	RsdSecCnt = PageBuf[14] + PageBuf[15] * 256;
	printuf16x("Reserved Sector Count : 0x%x\n",RsdSecCnt);
	SecPerClus = PageBuf[13];
	printuf16x("Sector per Clus : 0x%x\n",SecPerClus);
	BytesPerSec = PageBuf[12] * 256 + PageBuf[11];
	printuf16x("Bytes per Sector: 0x%x\n",BytesPerSec);
	RootEntCnt = PageBuf[18] * 256 + PageBuf[17];
	printuf16x("Root Entry Count : 0x%x\n",RootEntCnt);
	TotalSector = PageBuf[20] * 256 + PageBuf[19];
	printuf16x("Total Sector Count : 0x%x\n",TotalSector);

	FatSize16 = PageBuf[23] * 256 + PageBuf[22];
	if(FatSize16==0) 
	  { FAT_TYPE = FAT32; return; }	

 	FatStartSec  = BootSector + RsdSecCnt;
	RootStartSec = FatStartSec + 2 * FatSize16;
	FirstDataSec = RootStartSec + (RootEntCnt * 32 + (BytesPerSec - 1)) / BytesPerSec;
	printuf16x("Fat Start Sector : 0x%x\n",FatStartSec);
	printuf16x("Root Start Sector : 0x%x\n",RootStartSec);
	printuf16x("First Data Sector : 0x%x\n",FirstDataSec);

	FAT_TYPE = FAT16;
}

unsigned char  OpenFile(unsigned char *FileName)
{
	unsigned char data i, k;
	unsigned long data page;
	page = RootStartSec;
	while (1)
		{
			ReadPage(page, PageBuf);
	    	for (k=0; k<16; k++)
 			  {	
				if (PageBuf[k * 32] == 0x00) return 0;
				if (PageBuf[k * 32] == 0xE5) continue;
				if (!memcmp(FileName, &PageBuf[k * 32], 11))	  //file find
				    {	
					 CurrentClus = PageBuf[32 * k + 27] * 256 + PageBuf[32 * k + 26];
					 CurrentSec  = (CurrentClus - 2) * SecPerClus + FirstDataSec;
					 for (i=31; i>=28; i--) 
						DataRemain = (DataRemain << 8) | PageBuf[k * 32 + i];
					 
					 printu("File Name :");
					 for(i=0;i<11;i++)
					   printuf("%c",PageBuf[k * 32+i]);
					 printu("\n");
					 
					 printuf16x("File Size : 0x%x",DataRemain/0x10000);
					 printuf16x("%x\n",DataRemain%0x10000);
					 printuf16x("First Clus : 0x%x\n",CurrentClus);
					 printuf16x("First Sector : 0x%x\n",CurrentSec);

					 return 1;
					 }
			   }
	
			page++;
		}

}

unsigned int ReadFile()
{
	ReadPage(CurrentSec++, PageBuf);
	if (DataRemain < 512) 
		return (DataRemain);
	else
	{	DataRemain -= 512;
		return (512);
	}
}

void Flash_Reset()
{ 
	K9F_FUN = COMMAND;                     
	K9F5608 = 0xff;	      
	K9F_FUN = INACTIVE;
}

void ReadPage(unsigned int BlockPage,unsigned char *PageBuf)
{
    unsigned int data i;

	K9F_FUN = COMMAND;
	K9F5608 = 0x00;
	K9F_FUN = ADDRESS;
    K9F5608 = 0;				//A0-A7
    K9F5608 = BlockPage; 	    //A9-A16
	K9F5608 = BlockPage >> 8;   //A17-A24 
	K9F_FUN = D_DATA;

	i = 512;
    while(!(K9F_FUN & RB));

	while(i--) 
		*PageBuf++ = K9F5608;
	K9F_FUN = INACTIVE;
 }