双口ram读数据的速度太慢

系统结构与功能：

       lpc3131外接8k*8双口ram与8G Flash，从双口ram读取数据（来自FPGA），并存至Flash中。

问题：

       丢数据，系统速度远低于ram的读速与Flash的写速度。

  双口ram读数据直接采用指针，如下：

        for(i=0;i<tmp;i++)

      {

        nandflash.databuf[nandflash.ptr_buf] = *(volatile UNS_8 *)(EXT_SRAM0_0_BASE + ram.ptr);

        nandflash.ptr_buf++;

        ram.ptr++;

      }

Flash按页写的程序如下：

INT_32 nand_page_write(INT_32 devid,

                       void * buffer,

                       INT_32 bank_num,

                       INT_32 block_num,

                       INT_32 page_num)

{

  NAND_DRV_T *nanddrv = (NAND_DRV_T *) devid;

  NAND_FLASH_CTRL_REGS_T *nandreg = nanddrv->regptr;

  UNS_32 * pData;

  UNS_32 * pnfbuf[2];

  UNS_32 i,j,tmp;

  UNS_8 addr1 = 0;

  UNS_8 addr2 = 0;

  UNS_8 addr3 = (UNS_8)(((block_num<<6)&0x0C0)+(page_num&0x03F));

  UNS_8 addr4 = (UNS_8)((block_num>>2)&0x0FF);

  UNS_8 addr5 = (UNS_8)((block_num>>10)&0x07);

  pnfbuf[0] = (UNS_32 *) NANDFLASH_CTRL_S0_BASE;

  pnfbuf[1] = (UNS_32 *) (NANDFLASH_CTRL_S0_BASE + 0x400);

  nandreg->set_ce = NAND_SETCE_WP | NAND_SETCE_CV(bank_num);

  nandreg->set_cmd = NAND_CMD_SDIN;

  nandreg->set_addr = addr1;

  nandreg->set_addr = addr2;

  nandreg->set_addr = addr3;

  nandreg->set_addr = addr4;

  nandreg->set_addr = addr5;

  for(j=0;j<8;j++)

  {

    pData = (UNS_32 *)((UNS_8 *)buffer + j*512);

    tmp = j&0x01;

    for(i=0;i<128;i++)

    {

      *(pnfbuf[tmp]+i) = *(pData + i);

    }

    if(j>0)

    {

      while(!(nand_ioctl(devid, NAND_IRQ_STATUS, 3-tmp)));

      while((nand_ioctl(devid, NAND_IRQ_STATUS, 3-tmp)))nandreg->irq_status_raw = 0xFFFFFFFF;

    }

    nandreg->control_flow = NAND_CTRL_RD_RAM(4+tmp);

  }

  while(!(nand_ioctl(devid, NAND_IRQ_STATUS, 3)));

  while((nand_ioctl(devid, NAND_IRQ_STATUS, 3)))nandreg->irq_status_raw = 0xFFFFFFFF;

  nandreg->set_cmd = NAND_CMD_PAGEPROG;

  while((nand_ioctl(devid, NAND_RB_STATUS, bank_num)));

  while(!(nand_ioctl(devid, NAND_RB_STATUS, bank_num)));

  return 0;

}

为什么速度远低于芯片说明文档中的读写速度？？？

求指点，非常感谢！