对 LCD地址的疑问

    rLCDSADDR1 = ((LCD_ADDR >> 22) << 21) | ((M5D(LCD_ADDR >> 1)) <<  0);
    rLCDSADDR2 = M5D((LCD_ADDR + LCD_WIDTH * LCD_HEIGHT * 2) >> 1);
    rLCDSADDR3 = LCD_WIDTH*1;        

    saddr1  = info->fix.smem_start >> 1;
    saddr2  = info->fix.smem_start;
    saddr2 += info->fix.line_length * info->var.yres;
    saddr2 >>= 1;
    saddr3 = S3C2410_OFFSIZE(0) |
         S3C2410_PAGEWIDTH((info->fix.line_length / 2) & 0x3ff);