请问FLASH驱的读写！

请大家帮我看一下这个函数呀？我有点看不懂，别人写的？谢谢了呀！
请问：这里的地址： int NewSpareAddr = 2048 + 8*(startSectorAddr%8);
int NewDataAddr = 256*(startSectorAddr%8);
int NewSectorAddr = startSectorAddr/8;
为什么要这么算呀？算出的是是什么地址呢？
//ljm change :need to correct ecc
BOOL FMD_ReadSector(SECTOR_ADDR startSectorAddr, LPBYTE pSectorBuff,
                        PSectorInfo pSectorInfoBuff, DWORD dwNumSectors)
{
    DWORD      i;
    BYTE        eccBuf[8];
    ECCRegVal  eccRegVal;
    EccInfo eccOrigVal;
  // EccInfo  eccNewVal;
    DWORD EccData0,EccData1;
    unsigned short  *pU16Buf;

int NewSpareAddr = 2048 + 8*(startSectorAddr%8);
int NewDataAddr = 256*(startSectorAddr%8);
int NewSectorAddr = startSectorAddr/8;

pU16Buf=(unsigned short *)pSectorBuff;
// RETAILMSG(1, (TEXT("FlashDrv!FMD!FMD_ReadSector:  startSectorAddr = %x \r\n"), startSectorAddr));
    //  Sanity check
    if (!pSectorBuff && !pSectorInfoBuff || dwNumSectors > 1) {
#ifdef BOOT_LOADER
        EdbgOutputDebugString("Invalid parameters!\r\n"